Custom sorting with Pandas

问题

I have the following dataframe that I would like to sort first by Criticality and then by Name:

Name        Criticality
baz         High
foo         Critical
baz         Low
foo         Medium
bar         High
bar         Low
bar         Medium
...

I've been trying to do this using the answer provided in this post but I just can't get it to work.

The end result should be like this

Name        Criticality
bar         High
bar         Medium
bar         Low
baz         High
baz         Low
foo         Critical
foo         Medium

回答1:

One approach would be to use a custom dict to create a 'rank' column, we then use to sort with and then drop the column after sorting:

In [17]:
custom_dict = {'Critical':0, 'High':1, 'Medium':2, 'Low':3}  
df['rank'] = df['Criticality'].map(custom_dict)
df

Out[17]:

  Name Criticality  rank
0  baz        High     1
1  foo    Critical     0
2  baz         Low     3
3  foo      Medium     2
4  bar        High     1
5  bar         Low     3
6  bar      Medium     2

[7 rows x 3 columns]

In [19]:
# now sort by 'Name' and 'rank', it will first sort by 'Name' column first and then 'rank'
df.sort(columns=['Name', 'rank'],inplace=True)
df

Out[19]:

  Name Criticality  rank
4  bar        High     1
6  bar      Medium     2
5  bar         Low     3
0  baz        High     1
2  baz         Low     3
1  foo    Critical     0
3  foo      Medium     2

[7 rows x 3 columns]

In [21]:
# now drop the 'rank' column
df.drop(labels=['rank'],axis=1)

Out[21]:

  Name Criticality
4  bar        High
6  bar      Medium
5  bar         Low
0  baz        High
2  baz         Low
1  foo    Critical
3  foo      Medium

[7 rows x 2 columns]

来源：https://stackoverflow.com/questions/23279238/custom-sorting-with-pandas

标签

python

sorting

pandas