python, sort descending dataframe with pandas

python sorting pandas

I'm trying to sort a dataframe by descending. I put 'False' in the ascending argument, but my order is still ascending.

My code is:

from pandas import DataFrame
import pandas as pd

d = {'one':[2,3,1,4,5],
     'two':[5,4,3,2,1],
     'letter':['a','a','b','b','c']}

df = DataFrame(d)

test = df.sort(['one'], ascending=[False])

but the output is

  letter  one  two
2      b    1    3
0      a    2    5
1      a    3    4
3      b    4    2
4      c    5    1

Your code actually gives the desired results on pandas version 0.14.1, so you may want to upgrade if possible.

Since this question refers to syntax which has worked fine since 0.14.1, (and was a fairly obvious typo before that), probably should close as not-an-issue.

Merlin

New syntax (either):

 test = df.sort_values(['one'], ascending=[False])
 test = df.sort_values(['one'], ascending=[0])

You can do this for multiple columns too: test = df.sort_values(['one','two'], ascending=[0,0])

U2EF1

Edit: This is out of date, see @Merlin's answer.

[False], being a nonempty list, is not the same as False. You should write:

test = df.sort('one', ascending=False)

Just to gently point to the answers below to work with latest Pandas version.

@merlin here, look at my Answer.. SO has dropped it to the bottom.

M--

For pandas 0.17 and above, use this :

test = df.sort_values('one', ascending=False)

Since 'one' is a series in the pandas data frame, hence pandas will not accept the arguments in the form of a list.

I seriously doubt that "hence pandas will not accept the arguments in the form of a list." is true. It does accept ascending=[False] on pandas 0.19. Could you elaborate?

BTW, since typing "ascending=False" is a lot to type and I use it a lot, sort_values('one')[::-1] will work if you take the performance hit.

Vivekanand AIML

from pandas import DataFrame
import pandas as pd

d = {'one':[2,3,1,4,5],
 'two':[5,4,3,2,1],
 'letter':['a','a','b','b','c']}

df = DataFrame(d)

test = df.sort_values(['one'], ascending=False)
test

aspiring1

https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.sort_values.html

I don't think you should ever provide the False value in square brackets (ever), also the column values when they are more than one, then only they are provided as a list! Not like ['one'].

test = df.sort_values(by='one', ascending = False)

Use you square brackets, because you might need to sort multiple columns. Look at OP question.

python, sort descending dataframe with pandas

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