相关疑难解决方法(0)

假设我有一个df列'ID', 'col_1', 'col_2'.我定义了一个函数:

f = lambda x, y : my_function_expression.

现在我想应用fto df的两列'col_1', 'col_2'来逐元素地计算一个新列'col_3',有点像:

df['col_3'] = df[['col_1','col_2']].apply(f)  
# Pandas gives : TypeError: ('<lambda>() takes exactly 2 arguments (1 given)'

怎么做 ？

** 添加详细示例如下 ***

import pandas as pd

df = pd.DataFrame({'ID':['1','2','3'], 'col_1': [0,2,3], 'col_2':[1,4,5]})
mylist = ['a','b','c','d','e','f']

def get_sublist(sta,end):
    return mylist[sta:end+1]

#df['col_3'] = df[['col_1','col_2']].apply(get_sublist,axis=1)
# expect above to output df as below 

  ID  col_1  col_2            col_3
0  1      0 …

假设我的数据框包含以下数据:

>>> df = pd.DataFrame({'a':['l1','l2','l1','l2','l1','l2'],
                       'b':['1','2','2','1','2','2']})
>>> df
    a       b
0  l1       1
1  l2       2
2  l1       2
3  l2       1
4  l1       2
5  l2       2

l1应该对应,1而l2应该对应2.我想创建一个新列' c',对于每一行,c = 1if a = l1和b = 1(或a = l2和b = 2).如果a = l1和b = 2(或a = l2和b = 1)然后c = 0.

生成的数据框应如下所示:

  a …