python - How do I create a list index that loops through integers in another list -

i have list:

sentences = ['the number of adults read @ least 1 novel within past 12 months fell 47%.',  'fiction reading rose 2002 2008.', 'the decline in fiction reading last year occurred among men.',  'women read more fiction.', '50% more.', 'though decreased 10% on last decade.', 'men more read nonfiction.',  'young adults more read fiction.', 'just 54% of americans cracked open book of  kind last year.',  'but novels have suffered more nonfiction.'] 

and have list containing indexes of sequences of sentences in above list contain number.

index_groupings = [[0, 1], [4, 5], [8]] 

i want extract specified sentence sequences in variable "sentences" using indexes in variable "index_groupings" following output:

the number of adults read @ least 1 novel within past 12 months fell 47%.fiction reading rose 2002 2008.

50% more.though decreased 10% on last decade.

just 54% of americans cracked open book of kind last year.

so following:

for grouping in index_groupings:     if len(grouping) > 1:         print sentences[grouping[:]]     else:         print sentences[grouping[0]] 

when run that, error message says

typeerror: list indices must integers, not list 

the line print sentences[grouping[:]] trips up. there way loop through index sequences in list index_groupings returns correct output?

print ["".join(map(lambda x:sentences[x],i)) in index_groupings] 

you can use join , list comprehension. here.

output:['the number of adults read @ least 1 novel within past 12 months fell 47%. fiction reading rose 2002 2008.', '50% more. though decreased 10% on last decade.', 'just 54% of americans cracked open book of kind last year.']