Pandas 重新采样工作日并填写未填写

Question

I have the following test data frame:

                 data
date                  
2021-03-01  3968513.99
2021-03-02  5909640.34
2021-03-03  6452578.11
2021-03-04  7260439.94
2021-03-05  6659379.74
2021-03-08  6693275.88
2021-03-09  6861187.90
2021-03-10  6716384.27
2021-03-11  6772700.54
2021-03-12  6461420.20
2021-03-15  6005397.14
2021-03-16  4695128.31
2021-03-17  4271115.19
2021-03-18  3927571.69
2021-03-19  3329363.28
2021-03-22  3395927.62
2021-03-23  3163365.76
2021-03-24  2876007.38
2021-03-25  2812801.36
2021-03-26  2854624.55
2021-03-29  2893050.72
2021-03-30  2094476.41
2021-03-31  1923014.42
2021-04-01         NaN
2021-04-02         NaN
2021-04-05         NaN
2021-04-06  1428389.82
2021-04-07  1381988.35
2021-04-08  1256461.70
2021-04-09  1324881.19
2021-04-12  1374734.95
2021-04-13  1261978.35

When I run the following however resample and ffill:

test_df.resample("B").ffill()

I get exactly the same as above, ie nothing was filled. The first few dates of april are still NaN.

I'm trying to work out the exact logic that resample is doing here, even if I set the limit as very large (60 say) it still doesn't fill these values.

EDIT: When you remove the lines completely from the test data which are NaN, ffill then works fine when it adds the dates itself.

Answer 1

Using fillna or ffill before resampling should do the trick. Here is some code with the mean() aggregation method:

df.fillna(method='ffill').resample('B').mean()