Fix dataframes resampling method

Summary

Resampling logic contains syntax and semantic errors.

When e.g. resampling following dataframe:

2000-01-01 00:00:00   0
2000-01-01 00:00:08   8
2000-01-01 00:00:16  16
2000-01-01 00:00:24  24
2000-01-01 00:00:32  32
2000-01-01 00:00:40  40

with frequency 3 and interpolate inbetween, we get as result: (current behaviour)

2000-01-01 00:00:00   0.0
2000-01-01 00:00:03   3.0
2000-01-01 00:00:06   6.0
2000-01-01 00:00:09   9.0
2000-01-01 00:00:12  12.0
2000-01-01 00:00:15  15.0
2000-01-01 00:00:18  18.0
2000-01-01 00:00:21  21.0
2000-01-01 00:00:24  24.0
2000-01-01 00:00:27  24.0
2000-01-01 00:00:30  24.0
2000-01-01 00:00:33  24.0
2000-01-01 00:00:36  24.0
2000-01-01 00:00:39  24.0

Performing an interpolation after resampling would result in

2000-01-01 00:00:00   0.000000
2000-01-01 00:00:03   4.000000
2000-01-01 00:00:06   8.000000
2000-01-01 00:00:09  10.666667
2000-01-01 00:00:12  13.333333
2000-01-01 00:00:15  16.000000
2000-01-01 00:00:18  18.666667
2000-01-01 00:00:21  21.333333
2000-01-01 00:00:24  24.000000
2000-01-01 00:00:27  28.000000
2000-01-01 00:00:30  32.000000
2000-01-01 00:00:33  34.666667
2000-01-01 00:00:36  37.333333
2000-01-01 00:00:39  40.000000

But we want this:

2000-01-01 00:00:00   0.0
2000-01-01 00:00:03   3.0
2000-01-01 00:00:06   6.0
2000-01-01 00:00:09   9.0
2000-01-01 00:00:12  12.0
2000-01-01 00:00:15  15.0
2000-01-01 00:00:18  18.0
2000-01-01 00:00:21  21.0
2000-01-01 00:00:24  24.0
2000-01-01 00:00:27  27.0
2000-01-01 00:00:30  30.0
2000-01-01 00:00:33  33.0
2000-01-01 00:00:36  36.0
2000-01-01 00:00:39  39.0

Explain your context

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What is the expected correct behavior? What was your goal?

(What you should see instead.)

What is the current bug behavior?

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Was there an error message?

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Steps to reproduce

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