sorting datetime columns pandas

Question

I have a dataframe table that has columns containing datetime information. As you can see from the table below, the 2019-xx field is between the years 2018 and 2016 so I need to arrange it properly.

I tried to use .sort_index(axis=1, inplace=True) but in vain (I don't know why it has no effect at all).

Dataframe:

                      2017-12-31   2018-12-31  2019-12-31   2016-12-31  2020-06-30
Unnamed: 0
WaterFlow   -26084000.0 -257404000.0 -84066000.0  135075000.0         NaN
trailing1HourWaterFlow         NaN          NaN -84066000.0          NaN   6823000.0

• The problem is that:
  1. I don't know how to arrange columns orders when it's represented as datetime info.
  2. The table above seems strange since that "Unnamed: 0" row is empty and there's a space between the columns and rows unlike other ordinary dataframes.

Answer 1

I think you need convert the columns to datetimes, then do the sorting. If Unnamed: 0 is the index name you can remove it by using DataFrame.rename_axis:

df.columns = pd.to_datetime(df.columns)
df = df.sort_index(axis=1).rename_axis(None)