CODEWITHSUNDEEP
python
NickThyname
NickThyname

Reputation: 1

python Joining list elements into list of list

I am attempting to join certain list elements in a specific manner: assuming i have following lists:

simpleline= [ 4 ]
otherline= [ 5, 7 ]
nextline=[ 1, 2 ]

i want to generate following lists:

 middlelist=[ [ 4, 5 ] , [ 4, 7 ] ]

then finally:

finallist=[ [ 4, 5, 1] , [4, 7, 1] , [ 4, 5, 2 ] , [ 4, 7, 2 ] ]

i have attempted the first process in a cycle:

simpleline= [ 4 ]
otherline= [ 5, 7 ]
nextline=[ 1, 2 ]

middlelist=[]
for element in range(len(otherline)):
           snap=simpleline[0].append(otherline[element])
           middlelist.append(snap)

print middlelist

however this results in error:

 AttributeError: 'int' object has no attribute 'append'

i appreciate any help

Upvotes: 0

Views: 44

Answers (2)

vash_the_stampede
vash_the_stampede

Reputation: 4606

Can use list comprehension here, just need to concatenate for the final list 

middle = [[i, j] for i in simpleline for j in otherline]
# [[4, 5], [4, 7]]

final = [j + [i] for i in nextline for j in middle]
# [[4, 5, 1], [4, 7, 1], [4, 5, 2], [4, 7, 2]]

Upvotes: 0

sacuL
sacuL

Reputation: 51335

I would use itertools.product for this:

finallist = list(map(list, itertools.product(*[simpleline,otherline,nextline])))

>>> finallist
[[4, 5, 1], [4, 5, 2], [4, 7, 1], [4, 7, 2]]

If you need the middlelist too:

middlelist = list(map(list, itertools.product(*[simpleline,otherline])))

>>> middlelist
[[4, 5], [4, 7]]

Upvotes: 1

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