python write in file list of list with different separator

Question

I have a list of list like that :

liste = [["1-2","3-4"],["5-6"]]

I would like to write in a file like that :

1-2,3-4|5,6

I try this :

for l in liste:
    sortie.write(",".join(l)+"|")

but it writes:

1-2,3-4|5,6|

How can I delete (or don't write) the last pipe ?

Martijn Pieters · Accepted Answer · 2014-05-27 09:34:26Z

1

Use a list comprehension to join your lists in one .write() call:

sortie.write('|'.join([','.join(l) for l in liste]))

This replaces your for loop over liste.

Demo:

>>> liste = [["1-2","3-4"],["5-6"]]
>>> '|'.join([','.join(l) for l in liste])
'1-2,3-4|5-6'

answered May 27, 2014 at 9:34

Martijn Pieters

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3 Comments

Dee Over a year ago

that's neat, I'm afraid I don't understand why the first part of the nesting works: [','.join(l) for l in liste] . When i see this the result I expect is ['1-2,3-4,5-6'] nor do I get why it doesn't work, in the interpreter, when I omit the [] ','.join(l) for l in liste

Martijn Pieters Over a year ago

@Dee: there are nested lists; each list object in liste needs joining first (using ','), before joining those results with '|'.

Dee Over a year ago

yes, the logic I grasp, I'm failing to see how the result is reached though. weird I know. I think looking at it again now, if I imagine the removal of the quotes as more fundamental I start to see the elements coming together the way they appropriately do, rather than the commas being the key - even though they are the key. my mind block, must be some childhood trauma inhibiting me ;)

otus · Accepted Answer · 2014-05-27 09:34:33Z

1

Nested joins:

s = '|'.join(','.join(l) for l in liste)

answered May 27, 2014 at 9:34

otus

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Comments

Prashant Gaur · Accepted Answer · 2014-05-27 09:44:57Z

0

>>> lines = []
>>> for line in liste:
...     lines.append(','.join(map(str, line)))
... 
>>> print '|'.join(lines)
1-2,3-4|5-6
>>>

answered May 27, 2014 at 9:44

Prashant Gaur

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