加入嵌套的字符串列表

Question

I have a list of lists:

array = ['there is nothing','there is everything,',['there is','where']]  

and here's a small piece of code:

str2 = ""
for item in array:
    str2 += "".join(char for char in item)   

which gives :

'there is nothingthere is everything,there iswhere'  

How could I possibly add a space between each item of the outer list as well as the inner one?

The expected output string is :

'there is nothing there is everything, there is where'  

I referred to questions one and two ,though that dint work in my case , the first one gives something like:

str2=""
lst = [' {}'.format(elem) for elem in array]
for item in lst:
    str2 += "".join(char for char in item)

output :

" there is nothing there is everything, ['there is', 'where']"  

and the second one doesn't work for words.

Answer 1

I would define a function that can work on arbitrarily nested lists of strings:

array = ['there is nothing','there is everything,',['there is','where']]

def concat_string(array):
    ret = ""
    for item in array:
        if isinstance(item,list):
            ret += concat_string(item)
        else:
            ret += item + " "

    return ret

print concat_string(array)

Answer 2

How about:

array = ['there is nothing','there is everything,',['there is','where']]
s = ''
for i in array:
    if isinstance(i, list):
        for j in i:
            s = ' '.join((s, j)) if s != '' else j
    else:
        s = ' '.join((s, i)) if s != '' else i
print(s)

Answer 3

The best way i think is to flatten the list first and then join them by space.

import collections
def flatten(foo):
    for x in foo:
        if isinstance(x, collections.Iterable) and not isinstance(x, str):
            for y in flatten(x):
                yield y
        else:
            yield x

my_sentence = " ".join(flatten(array))

or, you can use this a single line solution as mentioned by @bhat irshad but it will not work for arbitrary nesting

In [1]: array = ['there is nothing','there is everything,',['there is','where']]

In [2]: " ".join([" ".join(s) if isinstance(s,list) else s for s in array])
Out[2]: 'there is nothing there is everything, there is where'

Answer 4

It should be:

array = ['there is nothing','there is everything,',['there is','where']]  
newstring = ''
for a in array :
    if type( a ) is str :
        newstring += a + " "
    else :
        newstring += ' '.join( a )

And it almost could be : ' '.join( [ ''.join(x) for x in array ] )

You can use ternary as well :

array = ['there is nothing','there is everything,',['there is','where']]  
newstring = ''
for a in array :
    newstring += a + " " if type( a ) is str else ' '.join( a )

Answer 5

using your question 1, the following would be a generic but not effient solution. 1. Add space to all elements of the list 2. merge them with our small code. 3. Trim spaces from both ends 4. remove duplicate spaces that may have been created.