pandas 按字符串长度对数据框进行排序
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Sort dataframe by string length
提问by AlexG
I want to sort by name length. There doesn't appear to be a keyparameter for sort_valuesso I'm not sure how to accomplish this. Here is a test df:
我想按名称长度排序。似乎没有key参数，sort_values所以我不确定如何完成此操作。这是一个测试df：
import pandas as pd
df = pd.DataFrame({'name': ['Steve', 'Al', 'Markus', 'Greg'], 'score': [2, 4, 2, 3]})
回答by jezrael
You can use reindexof indexof Seriescreated by lenwith sort_values:
您可以使用reindex的index的Series通过创建len具有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by moshfiqur
I found this solution more intuitive, specially if you want to do something depending on the column length later on.
我发现这个解决方案更直观，特别是如果你以后想根据列的长度做一些事情。
df['length'] = df['name'].str.len()
df.sort_values('length', ascending=False, inplace=True)
Now your dataframe will have a column with name lengthwith the value of string length from column namein it and the whole dataframe will be sorted in descending order.
现在您的数据框将有一个名称为列length的字符串长度值的列name，整个数据框将按降序排序。
回答by Thierry G.
The answer of @jezrael is great and explains well. Here is the final result :
@jezrael 的回答很棒并且解释得很好。这是最终结果：
index_sorted = df.name.str.len().sort_values(ascending=True).index
df_sorted = df.reindex(index_sorted)
df_sorted = df_sorted.reset_index(drop=True)
