Python Pandas df issue: "bound method NDFrame.head of Empty DataFrame"

Question

I'm building an empty dataframe for a basic calendar table, then populating with pd.date_range values in one column. The problem is the dataframe comes up as empty after append. Here's my code:

def date_calendar(table, startdate, enddate, datefreq):

# create a df
df = pd.DataFrame({
        'Year': [],
        'FY Year': [],
        'Quarter': [],
        'MonthNum': [],
        'YearMonth': [],
        'YearMonthShort': [],
        'YearMonthNum': [],
        'Date': [],
    })

# create a date_range specified in function inputs
per1 = pd.date_range(start=startdate,
                         end=enddate, freq=datefreq)

# make the date_range into a series because .append method doesn't work if per1 is not a series
per2 = per1.to_series()

# append series to df
df['Date'].append(per2)
return df

date_calendar(table, startdate='1-1-2019', enddate='6-30-2024', datefreq='D')

And my results are:

<bound method NDFrame.head of Empty DataFrame Columns: [Year, FY Year, Quarter, MonthNum, YearMonth, YearMonthShort, YearMonthNum, Date] Index: []>

score 1 · Accepted Answer · answered Aug 26 '21 at 17:28

When appending series to df, you need to assign the result back to df['Date'].

def date_calendar(startdate, enddate, datefreq):

# create a df
    df = pd.DataFrame({
            'Year': [],
            'FY Year': [],
            'Quarter': [],
            'MonthNum': [],
            'YearMonth': [],
            'YearMonthShort': [],
            'YearMonthNum': [],
            'Date': [],
        })

    # create a date_range specified in function inputs
    per1 = pd.date_range(start=startdate,
                             end=enddate, freq=datefreq)

    # make the date_range into a series because .append method doesn't work if per1 is not a series
    per2 = per1.to_series()

    # append series to df
    df['Date'] = df['Date'].append(per2)
    return df

date_calendar(startdate='1-1-2019', enddate='6-30-2024', datefreq='D')

Python Pandas df issue: "bound method NDFrame.head of Empty DataFrame"

1 Answers1