Concatenating elements in list of list in Python

Question

I have:

df1 = [['10103', 'Baldwin, C', 'SFEN'], ['10115', 'Wyatt, X', 'SFEN']]

What would be the best way to concatenate the items within so that I could get something like:

[['10103 - Baldwin, C', 'SFEN'], ['10115 - Wyatt, X', 'SFEN']]

If I try something like

for i in df1:
    df1[0:1] = [' - '.join(df1[0:1])]

I get TypeError: sequence item 0: expected str instance, list found.

join take list of string, you are passing list of list of string — sahasrara62
– sahasrara62, Commented Nov 14, 2020 at 3:03

Jason Yang · Accepted Answer · 2020-11-14 03:46:27Z

1

Do the same way as yours,

>>> df1 = [['10103', 'Baldwin, C', 'SFEN'], ['10115', 'Wyatt, X', 'SFEN']]
>>> for i, item in enumerate(df1):
...     df1[i] = [' - '.join(item[:2]), item[2]]
...
>>> df1
[['10103 - Baldwin, C', 'SFEN'], ['10115 - Wyatt, X', 'SFEN']]

Another way to go,

>>> df1 = [['10103', 'Baldwin, C', 'SFEN'], ['10115', 'Wyatt, X', 'SFEN']]
>>> df1 = [[' - '.join([item1, item2]), item3] for item1, item2, item3 in df1]
>>> df1
[['10103 - Baldwin, C', 'SFEN'], ['10115 - Wyatt, X', 'SFEN']]

answered Nov 14, 2020 at 3:46

Jason Yang

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