Customer Analysis

Classes and function to assist with customer retention analysis.

DaysBetweenPurchases

A class to plot the distribution of the average number of days between purchases per customer.

Attributes:

Name	Type	Description
purchase_dist_s	Series	The average number of days between purchases per customer.

Source code in pyretailscience/analysis/customer.py

class DaysBetweenPurchases:
    """A class to plot the distribution of the average number of days between purchases per customer.

    Attributes:
        purchase_dist_s (pd.Series): The average number of days between purchases per customer.
    """

    def __init__(self, df: pd.DataFrame) -> None:
        """Initialize the DaysBetweenPurchases class.

        Args:
            df (pd.DataFrame): A dataframe with the transaction data. The dataframe must have the columns customer_id
                and transaction_date, which must be non-null.

        Raises:
            ValueError: If the dataframe does doesn't contain the columns customer_id and transaction_id, or if the
                columns are null.

        """
        cols = ColumnHelper()
        required_cols = [cols.customer_id, cols.transaction_date]
        missing_cols = set(required_cols) - set(df.columns)
        if len(missing_cols) > 0:
            msg = f"The following columns are required but missing: {missing_cols}"
            raise ValueError(msg)

        self.purchase_dist_s = self._calculate_days_between_purchases(df)

    @staticmethod
    def _calculate_days_between_purchases(df: pd.DataFrame) -> pd.Series:
        """Calculate the average number of days between purchases per customer.

        Args:
            df (pd.DataFrame): A dataframe with the transaction data. The dataframe must have the columns customer_id
                and transaction_date, which must be non-null.

        Returns:
            pd.Series: The average number of days between purchases per customer.
        """
        cols = ColumnHelper()
        required_cols = [cols.customer_id, cols.transaction_date]
        missing_cols = set(required_cols) - set(df.columns)
        if len(missing_cols) > 0:
            msg = f"The following columns are required but missing: {missing_cols}"
            raise ValueError(msg)

        purchase_dist_df = df[[cols.customer_id, cols.transaction_date]].copy()
        purchase_dist_df[cols.transaction_date] = df[cols.transaction_date].dt.floor("D")
        purchase_dist_df = purchase_dist_df.drop_duplicates().sort_values([cols.customer_id, cols.transaction_date])
        purchase_dist_df["diff"] = purchase_dist_df[cols.transaction_date].diff()
        new_cust_mask = purchase_dist_df[cols.customer_id] != purchase_dist_df[cols.customer_id].shift(1)
        purchase_dist_df = purchase_dist_df[~new_cust_mask]
        purchase_dist_df["diff"] = purchase_dist_df["diff"].dt.days
        return purchase_dist_df.groupby(cols.customer_id)["diff"].mean()

    def plot(
        self,
        bins: int = 10,
        cumulative: bool = False,
        ax: Axes | None = None,
        percentile_line: float | None = None,
        title: str | None = None,
        x_label: str | None = None,
        y_label: str | None = None,
        source_text: str | None = None,
        **kwargs: dict[str, any],
    ) -> SubplotBase:
        """Plot the distribution of the average number of days between purchases per customer.

        Args:
            bins (int, optional): The number of bins to plot. Defaults to 10.
            cumulative (bool, optional): Whether to plot the cumulative distribution. Defaults to False.
            ax (Axes, optional): The Matplotlib axes to plot the graph on. Defaults to None.
            percentile_line (float, optional): The percentile to draw a line at. Defaults to None. When None then no
                line is drawn.
            title (str, optional): The title of the plot. Defaults to None.
            x_label (str, optional): The x-axis label. Defaults to None.
            y_label (str, optional): The y-axis label. Defaults to None.
            source_text (str, optional): The source text to add to the plot. Defaults to None.
            kwargs (dict[str, any]): Additional keyword arguments to pass to the plot

        Returns:
            SubplotBase: The Matplotlib axes of the plot
        """
        density = False
        if cumulative:
            density = True

        ax = self.purchase_dist_s.hist(
            bins=bins,
            cumulative=cumulative,
            ax=ax,
            density=density,
            color=COLORS["green"][500],
            **kwargs,
        )

        ax.xaxis.set_major_formatter(lambda x, pos: human_format(x, pos, decimals=0))

        ax = standard_graph_styles(ax)

        if cumulative:
            default_title = "Average Days Between Purchases cumulative Distribution"
            default_y_label = "Percentage of Customers"
            ax.yaxis.set_major_formatter(mtick.PercentFormatter(xmax=1, decimals=0))

        else:
            default_title = "Average Days Between Purchases Distribution"
            default_y_label = "Number of Customers"
            ax.yaxis.set_major_formatter(lambda x, pos: human_format(x, pos, decimals=0))

        ax = gu.standard_graph_styles(
            ax,
            title=gu.not_none(title, default_title),
            y_label=gu.not_none(y_label, default_y_label),
            x_label=gu.not_none(x_label, "Average Number of Days Between Purchases"),
        )

        if percentile_line is not None:
            if percentile_line > 1 or percentile_line < 0:
                raise ValueError("Percentile line must be between 0 and 1")
            ax.axvline(
                x=self.purchases_percentile(percentile_line),
                color=COLORS["red"][500],
                linestyle="--",
                lw=2,
                label=f"{percentile_line:.1%} of customers",
                ymax=0.96,
            )
            ax.legend(frameon=False)

        if source_text:
            gu.add_source_text(ax=ax, source_text=source_text)

        gu.standard_tick_styles(ax)

        return ax

    def purchases_percentile(self, percentile: float = 0.5) -> float:
        """Get the average number of days between purchases at a given percentile.

        Args:
            percentile (float): The percentile to get the average number of days between purchases at.

        Returns:
            float: The average number of days between purchases at the given percentile.
        """
        return self.purchase_dist_s.quantile(percentile)

__init__(df)

Initialize the DaysBetweenPurchases class.

Parameters:

Name	Type	Description	Default
df	DataFrame	A dataframe with the transaction data. The dataframe must have the columns customer_id and transaction_date, which must be non-null.	required

Raises:

Type	Description
ValueError	If the dataframe does doesn't contain the columns customer_id and transaction_id, or if the columns are null.

Source code in pyretailscience/analysis/customer.py

def __init__(self, df: pd.DataFrame) -> None:
    """Initialize the DaysBetweenPurchases class.

    Args:
        df (pd.DataFrame): A dataframe with the transaction data. The dataframe must have the columns customer_id
            and transaction_date, which must be non-null.

    Raises:
        ValueError: If the dataframe does doesn't contain the columns customer_id and transaction_id, or if the
            columns are null.

    """
    cols = ColumnHelper()
    required_cols = [cols.customer_id, cols.transaction_date]
    missing_cols = set(required_cols) - set(df.columns)
    if len(missing_cols) > 0:
        msg = f"The following columns are required but missing: {missing_cols}"
        raise ValueError(msg)

    self.purchase_dist_s = self._calculate_days_between_purchases(df)

plot(bins=10, cumulative=False, ax=None, percentile_line=None, title=None, x_label=None, y_label=None, source_text=None, **kwargs)

Plot the distribution of the average number of days between purchases per customer.

Parameters:

Name	Type	Description	Default
bins	int	The number of bins to plot. Defaults to 10.	10
cumulative	bool	Whether to plot the cumulative distribution. Defaults to False.	False
ax	Axes	The Matplotlib axes to plot the graph on. Defaults to None.	None
percentile_line	float	The percentile to draw a line at. Defaults to None. When None then no line is drawn.	None
title	str	The title of the plot. Defaults to None.	None
x_label	str	The x-axis label. Defaults to None.	None
y_label	str	The y-axis label. Defaults to None.	None
source_text	str	The source text to add to the plot. Defaults to None.	None
kwargs	dict[str, any]	Additional keyword arguments to pass to the plot	{}

Returns:

Name	Type	Description
SubplotBase	SubplotBase	The Matplotlib axes of the plot

Source code in pyretailscience/analysis/customer.py

def plot(
    self,
    bins: int = 10,
    cumulative: bool = False,
    ax: Axes | None = None,
    percentile_line: float | None = None,
    title: str | None = None,
    x_label: str | None = None,
    y_label: str | None = None,
    source_text: str | None = None,
    **kwargs: dict[str, any],
) -> SubplotBase:
    """Plot the distribution of the average number of days between purchases per customer.

    Args:
        bins (int, optional): The number of bins to plot. Defaults to 10.
        cumulative (bool, optional): Whether to plot the cumulative distribution. Defaults to False.
        ax (Axes, optional): The Matplotlib axes to plot the graph on. Defaults to None.
        percentile_line (float, optional): The percentile to draw a line at. Defaults to None. When None then no
            line is drawn.
        title (str, optional): The title of the plot. Defaults to None.
        x_label (str, optional): The x-axis label. Defaults to None.
        y_label (str, optional): The y-axis label. Defaults to None.
        source_text (str, optional): The source text to add to the plot. Defaults to None.
        kwargs (dict[str, any]): Additional keyword arguments to pass to the plot

    Returns:
        SubplotBase: The Matplotlib axes of the plot
    """
    density = False
    if cumulative:
        density = True

    ax = self.purchase_dist_s.hist(
        bins=bins,
        cumulative=cumulative,
        ax=ax,
        density=density,
        color=COLORS["green"][500],
        **kwargs,
    )

    ax.xaxis.set_major_formatter(lambda x, pos: human_format(x, pos, decimals=0))

    ax = standard_graph_styles(ax)

    if cumulative:
        default_title = "Average Days Between Purchases cumulative Distribution"
        default_y_label = "Percentage of Customers"
        ax.yaxis.set_major_formatter(mtick.PercentFormatter(xmax=1, decimals=0))

    else:
        default_title = "Average Days Between Purchases Distribution"
        default_y_label = "Number of Customers"
        ax.yaxis.set_major_formatter(lambda x, pos: human_format(x, pos, decimals=0))

    ax = gu.standard_graph_styles(
        ax,
        title=gu.not_none(title, default_title),
        y_label=gu.not_none(y_label, default_y_label),
        x_label=gu.not_none(x_label, "Average Number of Days Between Purchases"),
    )

    if percentile_line is not None:
        if percentile_line > 1 or percentile_line < 0:
            raise ValueError("Percentile line must be between 0 and 1")
        ax.axvline(
            x=self.purchases_percentile(percentile_line),
            color=COLORS["red"][500],
            linestyle="--",
            lw=2,
            label=f"{percentile_line:.1%} of customers",
            ymax=0.96,
        )
        ax.legend(frameon=False)

    if source_text:
        gu.add_source_text(ax=ax, source_text=source_text)

    gu.standard_tick_styles(ax)

    return ax

purchases_percentile(percentile=0.5)

Get the average number of days between purchases at a given percentile.

Parameters:

Name	Type	Description	Default
percentile	float	The percentile to get the average number of days between purchases at.	0.5

Returns:

Name	Type	Description
float	float	The average number of days between purchases at the given percentile.

Source code in pyretailscience/analysis/customer.py

def purchases_percentile(self, percentile: float = 0.5) -> float:
    """Get the average number of days between purchases at a given percentile.

    Args:
        percentile (float): The percentile to get the average number of days between purchases at.

    Returns:
        float: The average number of days between purchases at the given percentile.
    """
    return self.purchase_dist_s.quantile(percentile)

PurchasesPerCustomer

A class to plot the distribution of the number of purchases per customer.

Attributes:

Name	Type	Description
cust_purchases_s	Series	The number of purchases per customer.

Source code in pyretailscience/analysis/customer.py

class PurchasesPerCustomer:
    """A class to plot the distribution of the number of purchases per customer.

    Attributes:
        cust_purchases_s (pd.Series): The number of purchases per customer.
    """

    def __init__(self, df: pd.DataFrame) -> None:
        """Initialize the PurchasesPerCustomer class.

        Args:
            df (pd.DataFrame): A dataframe with the transaction data. The dataframe must comply with the
                contain customer_id and transaction_id columns, which must be non-null.

        Raises:
            ValueError: If the dataframe doesn't contain the columns customer_id and transaction_id, or if the columns
                are null.

        """
        cols = ColumnHelper()
        required_cols = [cols.customer_id, cols.transaction_id]
        missing_cols = set(required_cols) - set(df.columns)
        if len(missing_cols) > 0:
            msg = f"The following columns are required but missing: {missing_cols}"
            raise ValueError(msg)

        self.cust_purchases_s = df.groupby(cols.customer_id)[cols.transaction_id].nunique()

    def plot(
        self,
        bins: int = 10,
        cumulative: bool = False,
        ax: Axes | None = None,
        percentile_line: float | None = None,
        source_text: str | None = None,
        title: str | None = None,
        x_label: str | None = None,
        y_label: str | None = None,
        **kwargs: dict[str, any],
    ) -> SubplotBase:
        """Plot the distribution of the number of purchases per customer.

        Args:
            bins (int, optional): The number of bins to plot. Defaults to 10.
            cumulative (bool, optional): Whether to plot the cumulative distribution. Defaults to False.
            ax (Axes, optional): The Matplotlib axes to plot the graph on. Defaults to None.
            percentile_line (float, optional): The percentile to draw a line at. Defaults to None. When None then no
                line is drawn.
            source_text (str, optional): The source text to add to the plot. Defaults to None.
            title (str, optional): The title of the plot. Defaults to None.
            x_label (str, optional): The x-axis label. Defaults to None.
            y_label (str, optional): The y-axis label. Defaults to None.
            kwargs (dict[str, any]): Additional keyword arguments to pass to the plot function.

        Returns:
            SubplotBase: The Matplotlib axes of the plot
        """
        density = False
        if cumulative:
            density = True

        if x_label is None:
            x_label = "Number of purchases"

        ax = self.cust_purchases_s.hist(
            bins=bins,
            cumulative=cumulative,
            ax=ax,
            density=density,
            color=COLORS["green"][500],
            **kwargs,
        )

        ax.xaxis.set_major_formatter(lambda x, pos: human_format(x, pos, decimals=0))

        if cumulative:
            default_title = "Number of Purchases cumulative Distribution"
            default_y_label = "Percentage of customers"
            ax.yaxis.set_major_formatter(mtick.PercentFormatter(xmax=1, decimals=0))

        else:
            default_title = "Number of Purchases Distribution"
            default_y_label = "Number of customers"
            ax.yaxis.set_major_formatter(lambda x, pos: human_format(x, pos, decimals=0))

        ax = standard_graph_styles(
            ax,
            title=gu.not_none(title, default_title),
            x_label=x_label,
            y_label=gu.not_none(y_label, default_y_label),
        )

        if percentile_line is not None:
            if percentile_line > 1 or percentile_line < 0:
                raise ValueError("Percentile line must be between 0 and 1")
            ax.axvline(
                x=self.purchases_percentile(percentile_line),
                color=COLORS["red"][500],
                linestyle="--",
                lw=2,
                label=f"{percentile_line:.1%} of customers",
            )
            ax.legend(frameon=False)

        if source_text:
            gu.add_source_text(ax=ax, source_text=source_text)

        return ax

    def purchases_percentile(self, percentile: float = 0.5) -> float:
        """Get the number of purchases at a given percentile.

        Args:
            percentile (float): The percentile to get the number of purchases at.

        Returns:
            float: The number of purchases at the given percentile.
        """
        return self.cust_purchases_s.quantile(percentile)

    def find_purchase_percentile(self, number_of_purchases: int, comparison: str = "less_than_equal_to") -> float:
        """Find the percentile of the number of purchases.

        Args:
            number_of_purchases (int): The number of purchases to find the percentile of.
            comparison (str, optional): The comparison to use. Defaults to "less_than_equal_to". Must be one of
                less_than, less_than_equal_to, equal_to, not_equal_to, greater_than, or greater_than_equal_to.

        Returns:
            float: The percentile of the number of purchases.
        """
        ops = {
            "less_than": operator.lt,
            "less_than_equal_to": operator.le,
            "equal_to": operator.eq,
            "not_equal_to": operator.ne,
            "greater_than": operator.gt,
            "greater_than_equal_to": operator.ge,
        }

        if comparison not in ops:
            raise ValueError(
                "Comparison must be one of 'less_than', 'less_than_equal_to', 'equal_to', 'not_equal_to',",
                "'greater_than', 'greater_than_equal_to'",
            )

        return len(self.cust_purchases_s[ops[comparison](self.cust_purchases_s, number_of_purchases)]) / len(
            self.cust_purchases_s,
        )

__init__(df)

Initialize the PurchasesPerCustomer class.

Parameters:

Name	Type	Description	Default
df	DataFrame	A dataframe with the transaction data. The dataframe must comply with the contain customer_id and transaction_id columns, which must be non-null.	required

Raises:

Type	Description
ValueError	If the dataframe doesn't contain the columns customer_id and transaction_id, or if the columns are null.

Source code in pyretailscience/analysis/customer.py

def __init__(self, df: pd.DataFrame) -> None:
    """Initialize the PurchasesPerCustomer class.

    Args:
        df (pd.DataFrame): A dataframe with the transaction data. The dataframe must comply with the
            contain customer_id and transaction_id columns, which must be non-null.

    Raises:
        ValueError: If the dataframe doesn't contain the columns customer_id and transaction_id, or if the columns
            are null.

    """
    cols = ColumnHelper()
    required_cols = [cols.customer_id, cols.transaction_id]
    missing_cols = set(required_cols) - set(df.columns)
    if len(missing_cols) > 0:
        msg = f"The following columns are required but missing: {missing_cols}"
        raise ValueError(msg)

    self.cust_purchases_s = df.groupby(cols.customer_id)[cols.transaction_id].nunique()

find_purchase_percentile(number_of_purchases, comparison='less_than_equal_to')

Find the percentile of the number of purchases.

Parameters:

Name	Type	Description	Default
number_of_purchases	int	The number of purchases to find the percentile of.	required
comparison	str	The comparison to use. Defaults to "less_than_equal_to". Must be one of less_than, less_than_equal_to, equal_to, not_equal_to, greater_than, or greater_than_equal_to.	'less_than_equal_to'

Returns:

Name	Type	Description
float	float	The percentile of the number of purchases.

Source code in pyretailscience/analysis/customer.py

def find_purchase_percentile(self, number_of_purchases: int, comparison: str = "less_than_equal_to") -> float:
    """Find the percentile of the number of purchases.

    Args:
        number_of_purchases (int): The number of purchases to find the percentile of.
        comparison (str, optional): The comparison to use. Defaults to "less_than_equal_to". Must be one of
            less_than, less_than_equal_to, equal_to, not_equal_to, greater_than, or greater_than_equal_to.

    Returns:
        float: The percentile of the number of purchases.
    """
    ops = {
        "less_than": operator.lt,
        "less_than_equal_to": operator.le,
        "equal_to": operator.eq,
        "not_equal_to": operator.ne,
        "greater_than": operator.gt,
        "greater_than_equal_to": operator.ge,
    }

    if comparison not in ops:
        raise ValueError(
            "Comparison must be one of 'less_than', 'less_than_equal_to', 'equal_to', 'not_equal_to',",
            "'greater_than', 'greater_than_equal_to'",
        )

    return len(self.cust_purchases_s[ops[comparison](self.cust_purchases_s, number_of_purchases)]) / len(
        self.cust_purchases_s,
    )

plot(bins=10, cumulative=False, ax=None, percentile_line=None, source_text=None, title=None, x_label=None, y_label=None, **kwargs)

Plot the distribution of the number of purchases per customer.

Parameters:

Name	Type	Description	Default
bins	int	The number of bins to plot. Defaults to 10.	10
cumulative	bool	Whether to plot the cumulative distribution. Defaults to False.	False
ax	Axes	The Matplotlib axes to plot the graph on. Defaults to None.	None
percentile_line	float	The percentile to draw a line at. Defaults to None. When None then no line is drawn.	None
source_text	str	The source text to add to the plot. Defaults to None.	None
title	str	The title of the plot. Defaults to None.	None
x_label	str	The x-axis label. Defaults to None.	None
y_label	str	The y-axis label. Defaults to None.	None
kwargs	dict[str, any]	Additional keyword arguments to pass to the plot function.	{}

Returns:

Name	Type	Description
SubplotBase	SubplotBase	The Matplotlib axes of the plot

Source code in pyretailscience/analysis/customer.py

def plot(
    self,
    bins: int = 10,
    cumulative: bool = False,
    ax: Axes | None = None,
    percentile_line: float | None = None,
    source_text: str | None = None,
    title: str | None = None,
    x_label: str | None = None,
    y_label: str | None = None,
    **kwargs: dict[str, any],
) -> SubplotBase:
    """Plot the distribution of the number of purchases per customer.

    Args:
        bins (int, optional): The number of bins to plot. Defaults to 10.
        cumulative (bool, optional): Whether to plot the cumulative distribution. Defaults to False.
        ax (Axes, optional): The Matplotlib axes to plot the graph on. Defaults to None.
        percentile_line (float, optional): The percentile to draw a line at. Defaults to None. When None then no
            line is drawn.
        source_text (str, optional): The source text to add to the plot. Defaults to None.
        title (str, optional): The title of the plot. Defaults to None.
        x_label (str, optional): The x-axis label. Defaults to None.
        y_label (str, optional): The y-axis label. Defaults to None.
        kwargs (dict[str, any]): Additional keyword arguments to pass to the plot function.

    Returns:
        SubplotBase: The Matplotlib axes of the plot
    """
    density = False
    if cumulative:
        density = True

    if x_label is None:
        x_label = "Number of purchases"

    ax = self.cust_purchases_s.hist(
        bins=bins,
        cumulative=cumulative,
        ax=ax,
        density=density,
        color=COLORS["green"][500],
        **kwargs,
    )

    ax.xaxis.set_major_formatter(lambda x, pos: human_format(x, pos, decimals=0))

    if cumulative:
        default_title = "Number of Purchases cumulative Distribution"
        default_y_label = "Percentage of customers"
        ax.yaxis.set_major_formatter(mtick.PercentFormatter(xmax=1, decimals=0))

    else:
        default_title = "Number of Purchases Distribution"
        default_y_label = "Number of customers"
        ax.yaxis.set_major_formatter(lambda x, pos: human_format(x, pos, decimals=0))

    ax = standard_graph_styles(
        ax,
        title=gu.not_none(title, default_title),
        x_label=x_label,
        y_label=gu.not_none(y_label, default_y_label),
    )

    if percentile_line is not None:
        if percentile_line > 1 or percentile_line < 0:
            raise ValueError("Percentile line must be between 0 and 1")
        ax.axvline(
            x=self.purchases_percentile(percentile_line),
            color=COLORS["red"][500],
            linestyle="--",
            lw=2,
            label=f"{percentile_line:.1%} of customers",
        )
        ax.legend(frameon=False)

    if source_text:
        gu.add_source_text(ax=ax, source_text=source_text)

    return ax

purchases_percentile(percentile=0.5)

Get the number of purchases at a given percentile.

Parameters:

Name	Type	Description	Default
percentile	float	The percentile to get the number of purchases at.	0.5

Returns:

Name	Type	Description
float	float	The number of purchases at the given percentile.

Source code in pyretailscience/analysis/customer.py

def purchases_percentile(self, percentile: float = 0.5) -> float:
    """Get the number of purchases at a given percentile.

    Args:
        percentile (float): The percentile to get the number of purchases at.

    Returns:
        float: The number of purchases at the given percentile.
    """
    return self.cust_purchases_s.quantile(percentile)

TransactionChurn

A class to plot the churn rate by number of purchases.

Attributes:

Name	Type	Description
purchase_dist_df	DataFrame	The churn rate by number of purchases.
n_unique_customers	int	The number of unique customers in the dataframe.

Source code in pyretailscience/analysis/customer.py

class TransactionChurn:
    """A class to plot the churn rate by number of purchases.

    Attributes:
        purchase_dist_df (pd.DataFrame): The churn rate by number of purchases.
        n_unique_customers (int): The number of unique customers in the dataframe.
    """

    def __init__(self, df: pd.DataFrame, churn_period: float) -> None:
        """Initialize the TransactionChurn class.

        Args:
            df (pd.DataFrame): A dataframe with the transaction data. The dataframe must have the columns customer_id
                and transaction_date.
            churn_period (float): The number of days to consider a customer churned.

        Raises:
            ValueError: If the dataframe does doesn't contain the columns customer_id and transaction_id.
        """
        cols = ColumnHelper()
        required_cols = [cols.customer_id, cols.transaction_date]
        missing_cols = set(required_cols) - set(df.columns)
        if len(missing_cols) > 0:
            msg = f"The following columns are required but missing: {missing_cols}"
            raise ValueError(msg)

        purchase_dist_df = df[[cols.customer_id, cols.transaction_date]].copy()
        # Truncate the transaction_date to the day
        purchase_dist_df[cols.transaction_date] = df[cols.transaction_date].dt.floor("D")
        purchase_dist_df = purchase_dist_df.drop_duplicates()
        purchase_dist_df = purchase_dist_df.sort_values([cols.customer_id, cols.transaction_date])
        purchase_dist_df["transaction_number"] = purchase_dist_df.groupby(cols.customer_id).cumcount() + 1

        purchase_dist_df["last_transaction"] = (
            purchase_dist_df.groupby(cols.customer_id)[cols.transaction_date].shift(-1).isna()
        )
        purchase_dist_df["transaction_before_churn_window"] = purchase_dist_df[cols.transaction_date] < (
            purchase_dist_df[cols.transaction_date].max() - pd.Timedelta(days=churn_period)
        )
        purchase_dist_df["churned"] = (
            purchase_dist_df["last_transaction"] & purchase_dist_df["transaction_before_churn_window"]
        )

        purchase_dist_df = (
            purchase_dist_df[purchase_dist_df["transaction_before_churn_window"]]
            .groupby(["transaction_number"])["churned"]
            .value_counts()
            .unstack()
        )
        purchase_dist_df.columns = ["retained", "churned"]
        purchase_dist_df["churned_pct"] = purchase_dist_df["churned"].div(purchase_dist_df.sum(axis=1))
        self.purchase_dist_df = purchase_dist_df

        self.n_unique_customers = df[cols.customer_id].nunique()

    def plot(
        self,
        cumulative: bool = False,
        ax: Axes | None = None,
        title: str | None = None,
        x_label: str | None = None,
        y_label: str | None = None,
        source_text: str | None = None,
        **kwargs: dict[str, any],
    ) -> SubplotBase:
        """Plot the churn rate by number of purchases.

        Args:
            cumulative (bool, optional): Whether to plot the cumulative distribution. Defaults to False.
            ax (Axes, optional): The Matplotlib axes to plot the graph on. Defaults to None.
            title (str, optional): The title of the plot. Defaults to None.
            x_label (str, optional): The x-axis label. Defaults to None.
            y_label (str, optional): The y-axis label. Defaults to None.
            source_text (str, optional): The source text to add to the plot. Defaults to None.
            kwargs (dict[str, any]): Additional keyword arguments to pass to the plot function.

        Returns:
            SubplotBase: The Matplotlib axes of the plot
        """
        if cumulative:
            cumulative_churn_rate_s = self.purchase_dist_df["churned"].cumsum().div(self.n_unique_customers)
            ax = cumulative_churn_rate_s.plot.area(
                color=COLORS["green"][500],
                **kwargs,
            )
            ax.set_xlim(self.purchase_dist_df.index.min(), self.purchase_dist_df.index.max())
        else:
            ax = self.purchase_dist_df["churned_pct"].plot.bar(
                rot=0,
                color=COLORS["green"][500],
                width=0.8,
                **kwargs,
            )

        standard_graph_styles(
            ax,
            title=gu.not_none(title, "Churn Rate by Number of Purchases"),
            x_label=gu.not_none(x_label, "Number of Purchases"),
            y_label=gu.not_none(y_label, "% Churned"),
        )

        ax.yaxis.set_major_formatter(mtick.PercentFormatter(xmax=1.0))

        if source_text:
            gu.add_source_text(ax=ax, source_text=source_text)

        return ax

__init__(df, churn_period)

Initialize the TransactionChurn class.

Parameters:

Name	Type	Description	Default
df	DataFrame	A dataframe with the transaction data. The dataframe must have the columns customer_id and transaction_date.	required
churn_period	float	The number of days to consider a customer churned.	required

Raises:

Type	Description
ValueError	If the dataframe does doesn't contain the columns customer_id and transaction_id.

Source code in pyretailscience/analysis/customer.py

def __init__(self, df: pd.DataFrame, churn_period: float) -> None:
    """Initialize the TransactionChurn class.

    Args:
        df (pd.DataFrame): A dataframe with the transaction data. The dataframe must have the columns customer_id
            and transaction_date.
        churn_period (float): The number of days to consider a customer churned.

    Raises:
        ValueError: If the dataframe does doesn't contain the columns customer_id and transaction_id.
    """
    cols = ColumnHelper()
    required_cols = [cols.customer_id, cols.transaction_date]
    missing_cols = set(required_cols) - set(df.columns)
    if len(missing_cols) > 0:
        msg = f"The following columns are required but missing: {missing_cols}"
        raise ValueError(msg)

    purchase_dist_df = df[[cols.customer_id, cols.transaction_date]].copy()
    # Truncate the transaction_date to the day
    purchase_dist_df[cols.transaction_date] = df[cols.transaction_date].dt.floor("D")
    purchase_dist_df = purchase_dist_df.drop_duplicates()
    purchase_dist_df = purchase_dist_df.sort_values([cols.customer_id, cols.transaction_date])
    purchase_dist_df["transaction_number"] = purchase_dist_df.groupby(cols.customer_id).cumcount() + 1

    purchase_dist_df["last_transaction"] = (
        purchase_dist_df.groupby(cols.customer_id)[cols.transaction_date].shift(-1).isna()
    )
    purchase_dist_df["transaction_before_churn_window"] = purchase_dist_df[cols.transaction_date] < (
        purchase_dist_df[cols.transaction_date].max() - pd.Timedelta(days=churn_period)
    )
    purchase_dist_df["churned"] = (
        purchase_dist_df["last_transaction"] & purchase_dist_df["transaction_before_churn_window"]
    )

    purchase_dist_df = (
        purchase_dist_df[purchase_dist_df["transaction_before_churn_window"]]
        .groupby(["transaction_number"])["churned"]
        .value_counts()
        .unstack()
    )
    purchase_dist_df.columns = ["retained", "churned"]
    purchase_dist_df["churned_pct"] = purchase_dist_df["churned"].div(purchase_dist_df.sum(axis=1))
    self.purchase_dist_df = purchase_dist_df

    self.n_unique_customers = df[cols.customer_id].nunique()

plot(cumulative=False, ax=None, title=None, x_label=None, y_label=None, source_text=None, **kwargs)

Plot the churn rate by number of purchases.

Parameters:

Name	Type	Description	Default
cumulative	bool	Whether to plot the cumulative distribution. Defaults to False.	False
ax	Axes	The Matplotlib axes to plot the graph on. Defaults to None.	None
title	str	The title of the plot. Defaults to None.	None
x_label	str	The x-axis label. Defaults to None.	None
y_label	str	The y-axis label. Defaults to None.	None
source_text	str	The source text to add to the plot. Defaults to None.	None
kwargs	dict[str, any]	Additional keyword arguments to pass to the plot function.	{}

Returns:

Name	Type	Description
SubplotBase	SubplotBase	The Matplotlib axes of the plot

Source code in pyretailscience/analysis/customer.py

def plot(
    self,
    cumulative: bool = False,
    ax: Axes | None = None,
    title: str | None = None,
    x_label: str | None = None,
    y_label: str | None = None,
    source_text: str | None = None,
    **kwargs: dict[str, any],
) -> SubplotBase:
    """Plot the churn rate by number of purchases.

    Args:
        cumulative (bool, optional): Whether to plot the cumulative distribution. Defaults to False.
        ax (Axes, optional): The Matplotlib axes to plot the graph on. Defaults to None.
        title (str, optional): The title of the plot. Defaults to None.
        x_label (str, optional): The x-axis label. Defaults to None.
        y_label (str, optional): The y-axis label. Defaults to None.
        source_text (str, optional): The source text to add to the plot. Defaults to None.
        kwargs (dict[str, any]): Additional keyword arguments to pass to the plot function.

    Returns:
        SubplotBase: The Matplotlib axes of the plot
    """
    if cumulative:
        cumulative_churn_rate_s = self.purchase_dist_df["churned"].cumsum().div(self.n_unique_customers)
        ax = cumulative_churn_rate_s.plot.area(
            color=COLORS["green"][500],
            **kwargs,
        )
        ax.set_xlim(self.purchase_dist_df.index.min(), self.purchase_dist_df.index.max())
    else:
        ax = self.purchase_dist_df["churned_pct"].plot.bar(
            rot=0,
            color=COLORS["green"][500],
            width=0.8,
            **kwargs,
        )

    standard_graph_styles(
        ax,
        title=gu.not_none(title, "Churn Rate by Number of Purchases"),
        x_label=gu.not_none(x_label, "Number of Purchases"),
        y_label=gu.not_none(y_label, "% Churned"),
    )

    ax.yaxis.set_major_formatter(mtick.PercentFormatter(xmax=1.0))

    if source_text:
        gu.add_source_text(ax=ax, source_text=source_text)

    return ax