python 将元素替换为列表理解中的列表

Question

I am trying to use a list comprehension to make a list ready for output to csv file.

When I write

record[:] = [[', '.join(row)] if element == int(row[4]) else element for element in records]

It outputs what I want. But since csv output format needs to have lists in a list, I need to substitute the unchanged 'element' in else part to a list. I thus, tried

record[:] = [[', '.join(row)] if element == int(row[4]) else [element] for element in records]

But this does not work. This command cannot recognise and substitute correctly. Some elements found being substituted by the first method are not substituted by this method, which is quite odd. I thus, was wondering what has happened here.

Thanks.

Answer 1

It worked well when I tried ur code:

row = ['1','2','3','4','5']
records = [6,7,8,9,0,10,5,11,12]

res = [[', '.join(row)] if element == int(row[4]) else element for element in records]
res = [[', '.join(row)] if element == int(row[4]) else [element] for element in records]

Maybe u should give a sample of records , row and record