Python-How to combine list of lists Iff there is something common in those lists?

Question

Hey i need some help regarding list of list. For example i have a list :

parentList = [[["69", "742", "180","760", "05.07.2007", ""],
               ["69"," 768", "180", "785", "05.07.2007", ""], 
               ["69", "794","180","811","05072007",""], 
               ["69", "768", "180","785", "05.07.2007", ""]],
              [["69", "742", "180", "760", "05.07.2007", ""], 
               ["68", "717", "180", "735", "05.07.2007", ""]]]

Here "parentList" is one list containing multiple sublists

A=[["69", "742", "180","760", "05.07.2007", ""],
   ["69"," 768", "180", "785", "05.07.2007", ""], 
   ["69", "794","180","811","05072007",""], 
   ["69", "768", "180","785", "05.07.2007", ""]]

and

B= [["69", "742", "180", "760", "05.07.2007", ""], 
    ["68", "717", "180", "735", "05.07.2007", ""]]

I want to merge these two lists of lists within parentList if there is some common list between them. As you can clearly see in the example, that there is one list common in between A and B. I want the output as ```

parentList = [[["69", "742", "180","760", "05.07.2007", ""],
               ["69"," 768", "180", "785", "05.07.2007", ""], 
               ["69", "794","180","811","05072007",""], 
               ["69", "768", "180","785", "05.07.2007", ""],
               ["69", "742", "180", "760", "05.07.2007", ""], 
               ["68", "717", "180", "735", "05.07.2007", ""]]]

Note:- there can be multiple sublists in "parentList" with nothing is common to any sublist. Such unique sublists should retain their structure.

fix the formatting please, impossible to read the question – Aleksei Maide Feb 21 '18 at 08:57 — Aleksei Maide, Feb 21 '18 at 08:57
[related](https://stackoverflow.com/a/1388836/6464041) – Gábor Fekete Feb 21 '18 at 08:59 — Gábor Fekete, Feb 21 '18 at 08:59
Are the lowest level lists all the same length? – morsecodist Feb 21 '18 at 08:59 — morsecodist, Feb 21 '18 at 08:59
@AlekseiMaide fixed that. I hope it's readable now – AzkaGilani Feb 21 '18 at 09:01 — AzkaGilani, Feb 21 '18 at 09:01
@morsecodist Nope. lengths can be dynamic – AzkaGilani Feb 21 '18 at 09:01 — AzkaGilani, Feb 21 '18 at 09:01

Aleksei Maide · Answer 1 · 2018-02-21T10:28:57.633

Simple iterative worst case O(n3) solution would be to iterative over the lists and compare and merge if the match is found.

A=[["69", "742", "180","760", "05.07.2007", ""],
   ["69"," 768", "180", "785", "05.07.2007", ""], 
   ["69", "794","180","811","05072007",""], 
   ["69", "768", "180","785", "05.07.2007", ""]]

B= [["69", "742", "180", "760", "05.07.2007", ""], 
    ["68", "717", "180", "735", "05.07.2007", ""]]

def should_merge(A, B):
   if any((b in A) for b in B):
        return True

def merge(A, B):
  result = A
  for b in B:
    if (b not in A):
      result.append(b)
  return result

if should_merge(A, B):
  print(merge(A, B))

Prints this:

[['69', '742', '180', '760', '05.07.2007', ''], 
['69', ' 768', '180', '785', '05.07.2007', ''], 
['69', '794', '180', '811', '05072007', ''], 
['69', '768', '180', '785', '05.07.2007', ''], 
['68', '717', '180', '735', '05.07.2007', '']]

score 0 · Answer 2 · answered Feb 21 '18 at 09:26

A=[["69", "742", "180","760", "05.07.2007", ""],
   ["69"," 768", "180", "785", "05.07.2007", ""], 
   ["69", "794","180","811","05072007",""], 
   ["69", "768", "180","785", "05.07.2007", ""]]

B= [["69", "742", "180", "760", "05.07.2007", ""], 
    ["68", "717", "180", "735", "05.07.2007", ""]]


found = False

for a in A:
    if a in B:
        found = True
        break

if found:
    print(A+B)

Not most efficient one, since you are searching, but I think it solves your problem. :)

Narendra · Answer 3 · 2018-02-21T09:41:20.237

0

Just have idea with this

Try this:-

if any((x in A) for x in B):
    parentList.append([A,B])
print(parentList)

edited Feb 21 '18 at 09:41

answered Feb 21 '18 at 09:31

Narendra

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Vasilis G. · Accepted Answer · 2018-02-21T11:52:57.360

Here is another rather complicated approach that may suits your needs:

parentList = [[["69", "742", "180","760", "05.07.2007", ""],
               ["69"," 768", "180", "785", "05.07.2007", ""], 
               ["69", "794","180","811","05072007",""], 
               ["69", "768", "180","785", "05.07.2007", ""]],
              [["69", "742", "180", "760", "05.07.2007", ""], 
               ["68", "717", "180", "735", "05.07.2007", ""]]]

# Gather all elements of every sublist in a list along with the indice of the sublist e.g [0,1] of the parentList that they belong to.
elements = []
for subListIndex, subList in enumerate(parentList):
   for elem in subList:
      elements.append([subListIndex, elem])

# Check if two elements of different subList index have the same list and if they do, merge the two subLists.
for i in range(len(elements)):
   for j in [k for k in range(len(elements)) if not k==i]:
      if elements[i][1] == elements[j][1] and not elements[i][0]==elements[j][0]:
         parentList[elements[i][0]].extend(parentList[elements[j][0]])
         parentList[elements[j][0]] = [] # Needed in order to avoid reproducing already existing merged lists.

# Clear any empty subList.
parentList = [l for l in parentList if not l==[]]

# Print the final result.
for subList in parentList:
   for elem in subList:
      print(elem)
   print()

Output:

['69', '742', '180', '760', '05.07.2007', '']
['69', ' 768', '180', '785', '05.07.2007', '']
['69', '794', '180', '811', '05072007', '']
['69', '768', '180', '785', '05.07.2007', '']
['69', '742', '180', '760', '05.07.2007', '']
['68', '717', '180', '735', '05.07.2007', '']

`parentList[elements[j][0]].clear()` there is no method `clear()` — Sanket, Feb 21 '18 at 10:19
@Sanket thank you for pointing out. I edited my question. It did work though, using this method. — Vasilis G., Feb 21 '18 at 11:55

Python-How to combine list of lists Iff there is something common in those lists?

4 Answers4