CODEWITHSUNDEEP
pythonindexingpandastime-seriesoffset
Markus W
Markus W

Reputation: 1493

How to offset/shift a Pandas Dataframe into another year?

I have the following 15 minute data as a dataframe for 3 years. With the first two columns being the index.

2014-01-01 00:15:00  1269.6      
2014-01-01 00:30:00  1161.6      
2014-01-01 00:45:00  1466.4      
2014-01-01 01:00:00  1365.6      
2014-01-01 01:15:00  1362.6      
2014-01-01 01:30:00  1064.0      
2014-01-01 01:45:00  1171.2      
2014-01-01 02:00:00  1171.0      
2014-01-01 02:15:00  1330.4      
2014-01-01 02:30:00  1309.6      
2014-01-01 02:45:00  1308.4      
2014-01-01 03:00:00  1494.0

I would like to offset/shift the data into the previous year so that 2014-01-01 00:15:00 1269.6 will be converted into 2013-01-01 00:15:00 1269.6 .

I have used df = df.shift(-1, freq='15min') to shift the dataframe 15 mins into the past but would not like to offset/shift by the number of 15min intervals as this might cause errors in leap years and with clock changes.

Does anyone have a smooth solution for this?

Upvotes: 5

Views: 9810

Answers (1)

Jeff
Jeff

Reputation: 128948

In [13]: df = DataFrame(randn(10,1),index=date_range('20140101 00:15:00',freq='15T',periods=10))

In [14]: df
Out[14]: 
                            0
2014-01-01 00:15:00 -0.176117
2014-01-01 00:30:00  0.517030
2014-01-01 00:45:00  1.033585
2014-01-01 01:00:00 -0.284402
2014-01-01 01:15:00  0.476984
2014-01-01 01:30:00  0.356078
2014-01-01 01:45:00 -0.285609
2014-01-01 02:00:00  0.423048
2014-01-01 02:15:00  0.095823
2014-01-01 02:30:00 -1.123258

In [15]: df.index = df.index-pd.offsets.Day(365)

In [16]: df
Out[16]: 
                            0
2013-01-01 00:15:00 -0.176117
2013-01-01 00:30:00  0.517030
2013-01-01 00:45:00  1.033585
2013-01-01 01:00:00 -0.284402
2013-01-01 01:15:00  0.476984
2013-01-01 01:30:00  0.356078
2013-01-01 01:45:00 -0.285609
2013-01-01 02:00:00  0.423048
2013-01-01 02:15:00  0.095823
2013-01-01 02:30:00 -1.123258

Upvotes: 5

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