pandas 从列中可用的列表数据扩展行 [英] Pandas expand rows from list data available in column

问题描述

我在熊猫中有一个像这样的数据框:

I have a data frame like this in pandas:

 column1      column2
 [a,b,c]        1
 [d,e,f]        2
 [g,h,i]        3

预期输出:

column1      column2
  a              1
  b              1
  c              1
  d              2
  e              2
  f              2
  g              3
  h              3
  i              3

如何处理此数据?

推荐答案

您可以通过其构造函数和

You can create DataFrame by its constructor and stack:

 df2 = pd.DataFrame(df.column1.tolist(), index=df.column2)
        .stack()
        .reset_index(level=1, drop=True)
        .reset_index(name='column1')[['column1','column2']]
print (df2)

  column1  column2
0       a        1
1       b        1
2       c        1
3       d        2
4       e        2
5       f        2
6       g        3
7       h        3
8       i        3

如果需要按子集[['column1','column2']]进行更改排序，则还可以省略第一个reset_index:

If need change ordering by subset [['column1','column2']], you can also omit first reset_index:

df2 = pd.DataFrame(df.column1.tolist(), index=df.column2)
        .stack()
        .reset_index(name='column1')[['column1','column2']]
print (df2)
  column1  column2
0       a        1
1       b        1
2       c        1
3       d        2
4       e        2
5       f        2
6       g        3
7       h        3
8       i        3

另一种解决方案 DataFrame.from_records 从第一列创建DataFrame，然后通过Series > stack 和 join 转换为原始的DataFrame:

Another solution DataFrame.from_records for creating DataFrame from first column, then create Series by stack and join to original DataFrame:

df = pd.DataFrame({'column1': [['a','b','c'],['d','e','f'],['g','h','i']],
                   'column2':[1,2,3]})


a = pd.DataFrame.from_records(df.column1.tolist())
                .stack()
                .reset_index(level=1, drop=True)
                .rename('column1')

print (a)
0    a
0    b
0    c
1    d
1    e
1    f
2    g
2    h
2    i
Name: column1, dtype: object

print (df.drop('column1', axis=1)
         .join(a)
         .reset_index(drop=True)[['column1','column2']])

  column1  column2
0       a        1
1       b        1
2       c        1
3       d        2
4       e        2
5       f        2
6       g        3
7       h        3
8       i        3

这篇关于 pandas 从列中可用的列表数据扩展行的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！