从循环中的字符串列表创建新的列名 [英] Creating new column names from a list of strings in a loop

问题描述

让我们说我在熊猫中有以下列名: ["A"，"B"]

Let us say I have the following column names in pandas: ["A", "B"]

我的问题是我想使用一个for循环，该循环从列表中获取列名，并创建一个新的列名，其中包括列表中那些元素的一部分.

My problem is that I want to use a for loop that grabs the column names from the list and creates a new column name that includes part of those elements from the list.

在每次迭代中，我想创建以下内容:

In each iteration I would like to create the following:

a = ["A", "B"]
for elements i in a:
    elements + "_c" = SOME FUNCTION column <df.elements>   

这将导致添加两个新列，名称分别为A_c和B_c.

That should result in the addition of two new columns with names A_c and B_c.

推荐答案

您可以使用

You can use Series.apply in loop:

a = ["A", "B"]
for i in a:
    df[i + "_c"] =  df[i].apply(SOME FUNCTION) 

或 DataFrame.apply 与对于新的df add_suffix 然后 join 还原为原始内容:

Or DataFrame.apply with add_suffix for new df and then join to original:

df1 = df[a].apply(SOME FUNCTION).add_suffix('_c')
df = df.join(df1)

示例:

df = pd.DataFrame({'A':[4,5,4,5,5,4],
                   'B':[7,8,9,4,2,3],
                   'C':[1,3,5,7,1,0]})

print (df)
   A  B  C
0  4  7  1
1  5  8  3
2  4  9  5
3  5  4  7
4  5  2  1
5  4  3  0

def FUNCTION(x):
    return x + 10

a = ["A", "B"]

for i in a:
    df[i + "_c"] =  df[i].apply(FUNCTION) 

print (df)
   A  B  C  A_c  B_c
0  4  7  1   14   17
1  5  8  3   15   18
2  4  9  5   14   19
3  5  4  7   15   14
4  5  2  1   15   12
5  4  3  0   14   13

---

df = df.join(df[a].apply(FUNCTION).add_suffix('_c'))
print (df)
   A  B  C  A_c  B_c
0  4  7  1   14   17
1  5  8  3   15   18
2  4  9  5   14   19
3  5  4  7   15   14
4  5  2  1   15   12
5  4  3  0   14   13

这篇关于从循环中的字符串列表创建新的列名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！