How to return the difference of two multi-dimentional lists in Python?

Question

How can I compare two multidimensional lists in python 2.6.6 and show the different elements.

I am trying to compare multidimensional list A with multidimensional list B and output the elements that are present in list A but not present in list B

aArray=[]
a1=[1],[2],[3]
a2=[1],[4],[5]

bArray=[]
b1=[1],[2],[3]
b2=[1],[6],[7]

aArray.append(a1)
aArray.append(a2)
aArray
[([1], [2], [3]), ([1], [4], [5])]

bArray.append(b1)
bArray.append(b2)
bArray
[([1], [2], [3]), ([1], [6], [7])]

aArray.difference(bArray)

Expected result:

([1],[4],[5])

actual result:

aArray.difference(bArray)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'list' object has no attribute 'difference'

Possible duplicate of [Python, compute list difference](https://stackoverflow.com/questions/6486450/python-compute-list-difference) — Yasin Yousif, Dec 22 '18 at 18:20
@YasinYousif Tanks for the reply, but that example is not a multidimensional list — user3331063, Dec 22 '18 at 19:29
Is there any reason you have lists of length one in the innermost level? — timgeb, Dec 23 '18 at 15:46
Also, can the nesting be arbitrarily deep, irregular and can `A` and `B` have unqequal numbers of elements? — timgeb, Dec 23 '18 at 15:48

score 0 · Answer 1 · answered Dec 23 '18 at 15:41

0

I think a simple list comprehension will do:

a = [([1], [2], [3]), ([1], [4], [5])]
b = [([1], [2], [3]), ([1], [6], [7])]

print([x for x in a if x not in b])
[([1], [4], [5])]

answered Dec 23 '18 at 15:41

YOLO

20,181
5
20
40

score 0 · Answer 2 · answered Dec 23 '18 at 16:55

First of all .difference is a build in method for sets and does will not work for lists.

Hence, AttributeError: 'list' object has no attribute 'difference'

Just use of forloop to read the elemets in aArray and using if to print the

elements in aArary and not bArray using

[diff for diff in aArray if diff not in bArray]

How to return the difference of two multi-dimentional lists in Python?

2 Answers2