Sort dataframe by string length

问题

I want to sort by name length. There doesn't appear to be a key parameter for sort_values so I'm not sure how to accomplish this. Here is a test df:

import pandas as pd
df = pd.DataFrame({'name': ['Steve', 'Al', 'Markus', 'Greg'], 'score': [2, 4, 2, 3]})

回答1:

You can use reindex of index of Series created by len with sort_values:

print (df.name.str.len())
0    5
1    2
2    6
3    4
Name: name, dtype: int64

print (df.name.str.len().sort_values())
1    2
3    4
0    5
2    6
Name: name, dtype: int64

s = df.name.str.len().sort_values().index
print (s)
Int64Index([1, 3, 0, 2], dtype='int64')

print (df.reindex(s))
     name  score
1      Al      4
3    Greg      3
0   Steve      2
2  Markus      2

---

df1 = df.reindex(s)
df1 = df1.reset_index(drop=True)
print (df1)
     name  score
0      Al      4
1    Greg      3
2   Steve      2
3  Markus      2

回答2:

I found this solution more intuitive, specially if you want to do something depending on the column length later on.

df['length'] = df['name'].str.len()
df.sort_values('length', ascending=False, inplace=True)

Now your dataframe will have a column with the length of name column as value in it and the whole dataframe will be sorted in descending order.

来源：https://stackoverflow.com/questions/42516616/sort-dataframe-by-string-length