Recently updated to pandas 0.17.0 and I'm trying to order the columns in my dataframe alphabetically.
Here are the column labels as they currently are:
['UX2', 'RHO1', 'RHO3', 'RHO2', 'RHO4', 'UX1', 'UX4', 'UX3']
And I want them like this:
['RHO1', 'RHO2', 'RHO3', 'RHO4', 'UX1', 'UX2', 'UX3', 'UX4']
The only way I've been able to do this is following this from 3 years ago: How to change the order of DataFrame columns?
Is there a built-in way to do this in 0.17.0?
To sort the columns alphabetically here, you can just use sort_index:
df.sort_index(axis=1)
The method returns a reindexed DataFrame with the columns in the correct order.
This assumes that all of the column labels are strings (it won't work for a mix of, say, strings and integers). If this isn't the case, you may need to pass an explicit ordering to the reindex method.
You can just sort them and put them back. Suppose you have this:
df = pd.DataFrame()
for i, n in enumerate(['UX2', 'RHO1', 'RHO3', 'RHO2', 'RHO4', 'UX1', 'UX4', 'UX3']):
df[n] = [i]
It looks like this:
df
UX2 RHO1 RHO3 RHO2 RHO4 UX1 UX4 UX3
0 0 1 2 3 4 5 6 7
Do this:
df = df[ sorted(df.columns)]
And you should see this:
df
RHO1 RHO2 RHO3 RHO4 UX1 UX2 UX3 UX4
0 1 3 2 4 5 0 7 6
Create a list of the columns labels in the order you want.
cols = ['RHO1', 'RHO2', 'RHO3', 'RHO4', 'UX1', 'UX2', 'UX3', 'UX4']
Then assign this order to your DataFrame df:
df = df[cols]
