如何使用python-pptx替换现有折线图的数据？

Question

I have a prebuilt and populated powerpoint presentation where I am modifying the data for charts and tables. I would like to retain all formatting (and much of the text), but replace the data in a line chart within a slide.

I have a function that will replace the data using a pandas data frame that works with bar charts.

def replaceCategoryChart(df, chart, skipLastCol=0):
    """
    Replaces Category chartdata for a simple series chart. e.g. Nonfarm Employment

    Parameters:
    df: dataframe containing new data. column 0 is the categories
    chart: the powerpoint shape chart.
    skipLast: 0=don't skip last column, 1+ will skip that many columns from the end

    Returns: replaced chart(?)
    """
    cols1= list(df)
    #print(cols1)
    #create chart data object
    chart_data = CategoryChartData()
    #create categories
    chart_data.categories=df[cols1[0]]
    # Loop over all series
    for col in cols1[1:-skipLastCol]:
        chart_data.add_series(col, df[col])
    #replace chart data
    chart.replace_data(chart_data)

...
S0_L=  pd.read_excel(EXCEL_BOOK, sheet_name="S0_L", usecols="A:F")
S0_L_chart = prs.slides[0].shapes[3].chart
print(S0_L)
replaceCategoryChart(S0_L, S0_L_chart)
...

The python file runs successfully, however, when I open the powerpoint file I get the error

Powerpoint found a problem with content in Name.pptx. 

Powerpoint can attempt to repair the presentation.

If you trust the source of this presentation, click Repair.

After clicking repair, the slide I attempted to modify is replaced by a blank layout.

Because this function works for bar charts, I think there is a mistake in the way I am understanding how to use replace_data() for a line chart.

Thank you for your help!

Answer 1

If your "line chart" is an "XY Scatter" chart, you'll need a different chart-data object, the XyChartData object and then to populate its XySeries objects: https://python-pptx.readthedocs.io/en/latest/api/chart-data.html#pptx.chart.data.XyChartData

I would recommend starting by getting it working using literal values, eg "South" and 1.05 , and then proceed to supply the values from Pandas dataframes. That way you're sure the python-pptx part of your code is properly structured and you'll know where to go looking for any problems that arise.

Answer 2

As scanny mentioned, replace_data() does work for category line charts.

The repair error was (probably) caused by incorrectly adding series data, (there was a bad loop, corrected below).

    # Loop over all series
    for col in cols1[1:len(cols1)-skipLastCol]:
        print('Type of column is ' + str(type(col)))
        chart_data.add_series(col, df[col])