print two dimensional list

Question

I have a list, in which is another list and I want to doc.write(a)

a = [[1, 2, "hello"],
     [3, 5, "hi There"],
     [5,7,"I don't know"]]
doc.write(''.join(a))



TypeError: sequence item 0: expected str instance, list found

How can I handle this, do I have to make a for-loop in which I join and add all the sublists?

The real goal was to make it somehow readable for human beeing, but I didn't wanted a finished solution from you.

Answer 1

There are different legal things you can do, and no way for anyone to say which one is right without knowing which one you want.

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First, you can just write the str or repr of a:

>>> a=[[1, 2, "hello"],[3, 5, "hi There"],[5,7,"I don't know"]]
>>> repr(a)
'[[1, 2, \'hello\'], [3, 5, \'hi There\'], [5, 7, "I don\'t know"]]'

Note that this is what print does (it prints the str of whatever you give it—although with a list, the str is identical to the repr; they're both effectively '[' + ', '.join(map(repr, self)) + ']').

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Second, you could use a format that's designed for data persistent, like JSON:

>>> json.dumps(a)
'[[1, 2, "hello"], [3, 5, "hi There"], [5, 7, "I don\'t know"]]'

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Third, you can join together the repr of each element of a in some way of your choosing, which is trivial with a map or a comprehension. For example:

>>> '[' + ', '.join(map(repr, a)) + ']'
'[[1, 2, \'hello\'], [3, 5, \'hi There\'], [5, 7, "I don\'t know"]]'

… or …

>>> 'My stuff includes: ' + ','.join(map(repr, a)) + '\n'
'My stuff includes: [1, 2, \'hello\'],[3, 5, \'hi There\'],[5, 7, "I don\'t know"]\n'

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Or you can do the same thing recursively.

Or you can flatten the list (e.g., flatten it one step with itertools.chain, or recursively with the recipes from the itertools docs or with the more-itertools package) and then stringify the pieces however you want and then join them up.

Or you can just write the word LIST.

All of those are perfectly valid things to pass to write.

Answer 2

I was looking for an answer to this as well. After reading the comments here, this is what I came up with:

I was looking for an answer to this as well. After reading the comments here, this is what I came up with:

','.join(str(' '.join(str(x) for x in v)) for v in a)

This creates something like:

1 2 hello,3 5 hi There,5 7 I don't know

If you want all spaces as delimiters, then use ' ' instead of ',' at the front.