How to create a long string by concatenating two lists

[nikhilkumar]

my question here
I want to create long_string by concatenating the items in the list previously created
and also I have to make sure to put a space betweeen the names in the list. I have written the following code. But it's giving me the following error. I dont know why.

Error:
File "<ipython-input-44-fee3cf9fac7b>", line 7
print ''.join(str(n)+s for (n,s) in zip(list1, list2))
^
SyntaxError: invalid syntax

list1 = [1,2,3,4,5]
list2 = ["one", "two", "three", "four", "five"]
print (''.join([str(a) +" "+ b for a,b in zip(list1,list2)]))

Error:
File "<ipython-input-44-fee3cf9fac7b>", line 7
print ''.join(str(n)+s for (n,s) in zip(list1, list2))
^
SyntaxError: invalid syntax

[ichabod801]

Works for me, although I would join on a space or other non-empty string.

From the error you've posted, I would expect the problem is actually on the line before, maybe a missing comma or quote.

[Larz60+]

you might want to add a newline:

print (''.join([str(a) +" "+ b + '\n' for a,b in zip(list1,list2)]))

[wavic]

" ".join(list1.extend(list2))

[ichabod801]

@wavic: I think they want to interleave them, not one then the other. And that doesn't work anyway.

[micseydel]

" ".join(list1.extend(list2))

Output:
>>> " ".join([].extend([]))

Traceback (most recent call last):
 File "<pyshell#1>", line 1, in <module>
   " ".join([].extend([]))
TypeError: can only join an iterable
>>> print([].extend([]))
None

[wavic]

An empty list is None, yes.

Anyway, it works for me. I've just tried it

l1 = list(range(10))
l2 = list(range(11, 20))

print(' '.join([str(i) for i in l1.extend(l2)]))

[micseydel]

An empty list is None, yes.

I don't understand what you mean by this.

it works for me. I've just tried it

What output are you getting?

Output:
$ python
Python 2.7.12 (v2.7.12:d33e0cf91556, Jun 26 2016, 12:10:39) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> l1 = list(range(10))
>>> l2 = list(range(11, 20))
>>> print(' '.join([str(i) for i in l1.extend(l2)]))
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
TypeError: 'NoneType' object is not iterable
>>> ^D
$ python3
Python 3.5.2 (v3.5.2:4def2a2901a5, Jun 26 2016, 10:47:25) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> l1 = list(range(10))
>>> l2 = list(range(11, 20))
>>> print(' '.join([str(i) for i in l1.extend(l2)]))
Traceback (most recent call last):
 File "<stdin>", line 1, in <module>
TypeError: 'NoneType' object is not iterable
>>> 

[ichabod801]

An empty list is None, yes.

Output:
>>> [] is None
False

???

[wavic]

I was meaning it's equivalent when you get None

In [1]: l = []

In [2]: bool(l)
Out[2]: False

In [3]: bool(None)
Out[3]: False