Invert a single column in a DataFrame

Question

I do have a DataFrame mxn and would like to flip one column in similar way to list flip eg:

list1 = [1,2,3,4]
list2 = list1[::1]

so list2 looks like this: [4,3,2,1]

How to apply something similat to a DataFrame to a column but keep order of all rows and other columns so I flip the values in the single column only:

eg

df1 =

    col1    col2
1    cat     1
2    dog     2
3    fish    3
4    bird    4
5    mouse   5

to df2

    col1    col2
1    cat     5
2    dog     4
3    fish    3
4    bird    2
5    mouse   1

Answer 1

The simplest way of doing this would be:

df.col2 = df.col2.values[::-1]
df

    col1  col2
1    cat     5
2    dog     4
3   fish     3
4   bird     2
5  mouse     1

---

Or, using df.assign (to return a copy, not as efficient as inplace assignment):

df2 = df.assign(col2=df.col2.values[::-1])
df2

    col1  col2
1    cat     5
2    dog     4
3   fish     3
4   bird     2
5  mouse     1

Answer 2

Try concating this to your dataframe.

df1['col2'].loc[::-1]

It should work.

Answer 3

you can do :

>>> df1
   0  1  2
0  1  2  3
1  4  5  6
2  7  8  9
>>> df1[0]=df1[0].loc[::-1].reset_index(drop=True)
>>> df1
   0  1  2
0  7  2  3
1  4  5  6
2  1  8  9