def generate_column_probability_df(df, target_col):
    """
    Generates a dataframe containing the probability of a target variable within the dataframe.

    Parameters
    ----------
    df : DataFrame
        The dataframe containing the target variable
    target_var : string
        The key name for the target variable column

    Returns
    -------
    DataFrame
        Dataframe containing the target variable and the probabilities of the target occurring within the dataframe.
    """

    return (df[target_col].value_counts(dropna=False)/df[target_col].count()).reset_index().\
                rename(columns={'index': target_col, target_col : target_col + '_proba'})