I need the standard deviation of column distance for each row in my dataframe.
Dataframe df_stats:
a1/a2 distance mean_distance
date_time
2021-10-29T21:00:00+00:00 105.007574 -2.530492 0.234318
2021-10-29T22:00:00+00:00 104.459527 -5.232787 0.012537
2021-10-29T23:00:00+00:00 104.648467 1.807101 0.093432
2021-10-30T00:00:00+00:00 104.758201 1.048046 0.164502
2021-10-30T01:00:00+00:00 104.820132 0.591004 0.246095
2021-10-30T02:00:00+00:00 104.474062 -3.307024 -0.194917
2021-10-30T03:00:00+00:00 104.284146 -1.819483 -0.231843
2021-10-30T04:00:00+00:00 104.072383 -2.032697 -0.249918
2021-10-30T05:00:00+00:00 103.690546 -3.675699 -0.484996
2021-10-30T06:00:00+00:00 103.755979 0.630837 -0.823674
2021-10-30T07:00:00+00:00 102.721667 -10.018720 -1.181811
2021-10-30T08:00:00+00:00 102.998153 2.687995 -1.015365
2021-10-30T09:00:00+00:00 103.236159 2.308109 -0.876012
2021-10-30T10:00:00+00:00 103.471932 2.281216 -0.930593
2021-10-30T11:00:00+00:00 103.376928 -0.918579 -1.142659
2021-10-30T12:00:00+00:00 103.587805 2.037809 -1.110613
2021-10-30T13:00:00+00:00 104.359756 7.424508 -0.468987
2021-10-30T14:00:00+00:00 104.612493 2.418853 -0.383811
2021-10-30T15:00:00+00:00 104.607392 -0.048755 -0.562828
2021-10-30T16:00:00+00:00 104.846049 2.278849 -0.203495
2021-10-30T17:00:00+00:00 104.997437 1.442872 -0.004827
Trying to do it this way:
df_stats['std'] = df_stats.distance.std(axis=1)
But I get this error:
No axis named 1 for object type <class 'pandas.core.series.Series'>
Why is it not working?
>Solution :
Why is it not working?
Because axis=1 is for std per columns, but you count Series, df_stats.distance, there is no columns so error raised.
If use std of column, output is scalar:
print (df_stats.distance.std())
df_stats['std'] = df_stats.distance.std()
If need processing per multiple columns then axis=1 count std per rows:
df_stats['std'] = df_stats[['distance','a1/a2','mean_distance']].std(axis=1)
If need std per some datetimes, e.g. days:
df_stats['std'] = df_stats.groupby(pd.Grouper(freq='d')).distance.transform('std')