merging of lists

[hidrkannan]

aList = [1,2,3,4,5]
bList = [4,5,6,7,8]
cList = [7,8,9,10,11]
 
dList = [100,200,300]
eList = [100,400,500]
 
list1 = list(set(aList) | set(bList) |set(cList))
list2 = list(set(dList) | set(eList))
 
print list1,list2
 

I have "n" lists each having a set of integer values. I would like to merge the list and get resulant or resultants list if there is at least one element that is common in both the list.

In the above sample code, I see aList and bList have common elements and similarly bList and cList. Hence I obtained list1 merging this. Similary dList and eList are having common element and hence merged dList and eList as list2.

I would like to know how to write a consice code looping over each list to obtain the resultant(s) list.

Thanks in advance.

SKN

[ghostdog74]

aList = [1,2,3,4,5]
bList = [4,5,6,7,8]
cList = [7,8,9,10,11]
 
dList = [100,200,300]
eList = [100,400,500]
 
list1 = list(set(aList) | set(bList) |set(cList))
list2 = list(set(dList) | set(eList))
 
print list1,list2
 

I have "n" lists each having a set of integer values. I would like to merge the list and get resulant or resultants list if there is at least one element that is common in both the list.

In the above sample code, I see aList and bList have common elements and similarly bList and cList. Hence I obtained list1 merging this. Similary dList and eList are having common element and hence merged dList and eList as list2.

I would like to know how to write a consice code looping over each list to obtain the resultant(s) list.

Thanks in advance.

SKN

>>> set(aList+bList+cList)
set([1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
 

[bartonc]

Yes. 5.7.1 Set Objects come in very handy. Thanks, GD.

[hidrkannan]

The problem is to identify the lists that have common elements programatically . I have shown as an example that shows aList, bList, & cList have common elements and hence merged as list1.

Actually, I need to loop over and compare 2 lists and if have common elements merge as one list, and continue through the lists again. I am looking for a concise code to get this.

Thanks
SKN

[bartonc]

The problem is to identify the lists that have common elements programatically . I have shown as an example that shows aList, bList, & cList have common elements and hence merged as list1.

Actually, I need to loop over and compare 2 lists and if have common elements merge as one list, and continue through the lists again. I am looking for a concise code to get this.

Thanks
SKN

This will compare the 0th to the 1st, the 1st to the 2nd and the 2nd to the 0th, in that order:

>>> aList = [1,2,3,4,5]
>>> bList = [4,5,6,7,8]
>>> cList = [7,8,9,10,11]
>>> allLists = [aList, bList, cList]
>>> stopat = len(allLists) - 1
>>> for i, thisList in enumerate(allLists):
...     nextIndex = (i + 1, 0)[i == stopat]
...     result = set(thisList).intersection(set(allLists[nextIndex]))
...     if result:
...         print result
...         
set([4, 5])
set([8, 7])
>>> 

[hidrkannan]

This will compare the 0th to the 1st, the 1st to the 2nd and the 2nd to the 0th, in that order:

>>> aList = [1,2,3,4,5]
>>> bList = [4,5,6,7,8]
>>> cList = [7,8,9,10,11]
>>> allLists = [aList, bList, cList]
>>> stopat = len(allLists) - 1
>>> for i, thisList in enumerate(allLists):
...     nextIndex = (i + 1, 0)[i == stopat]
...     result = set(thisList).intersection(set(allLists[nextIndex]))
...     if result:
...         print result
...         
set([4, 5])
set([8, 7])
>>> 

I can substitute union in place of intersection to get the result. But is not still sufficient to get the desired result completely of getting two list as shown in my original posting.

Need your help.

Thanks
SKN

[bartonc]

I can substitute union in place of intersection to get the result. But is not still sufficient to get the desired result completely of getting two list as shown in my original posting.

Need your help.

Thanks
SKN

Yep. You are right about that. I missed part of your spec and going sequentially doesn't quite to a complete job. Please post some of your work so that we may see where you have gotten on improving on my post. Thanks.

[hidrkannan]

aList = [1,2,3,4,5]
bList = [4,5,6,7,8]
cList = [7,8,9,10,11]
dList = [100,200,300,400]
eList = [100,600,700]
allLists = [aList, bList, cList,dList,eList]
flag = 1
resultList = []
while (flag == 1):
    listCount = len(allLists)
    count = 0
    removeList = []
    for i in range(0,listCount-1):        
        if len((set(allLists[0]) & set(allLists[i+1]))) > 0:
            count = count + 1
            set(allLists[0]).union(set(allLists[i+1]))
            removeList.append(allLists[i+1])
            count = count + 1
            allLists[0] = list(set(allLists[0]).union(set(allLists[i+1])))            
    if len(allLists):
        resultList.append(allLists[0])
        allLists.remove(allLists[0])
    for tempList in removeList:
        if tempList in allLists:
            allLists.remove(tempList)
    if count == 0:
        flag = 0
print resultList
 

The above code does the job, but I feel it is lengthy and rounabout...

Thanks
SKN

[bartonc]

aList = [1,2,3,4,5]
bList = [4,5,6,7,8]
cList = [7,8,9,10,11]
dList = [100,200,300,400]
eList = [100,600,700]
allLists = [aList, bList, cList,dList,eList]
flag = 1
resultList = []
while (flag == 1):
    listCount = len(allLists)
    count = 0
    removeList = []
    for i in range(0,listCount-1):        
        if len((set(allLists[0]) & set(allLists[i+1]))) > 0:
            count = count + 1
            set(allLists[0]).union(set(allLists[i+1]))
            removeList.append(allLists[i+1])
            count = count + 1
            allLists[0] = list(set(allLists[0]).union(set(allLists[i+1])))            
    if len(allLists):
        resultList.append(allLists[0])
        allLists.remove(allLists[0])
    for tempList in removeList:
        if tempList in allLists:
            allLists.remove(tempList)
    if count == 0:
        flag = 0
print resultList
 

The above code does the job, but I feel it is lengthy and rounabout...

Thanks
SKN

Here it is a bit simplified. But, if you'll notice, with the order of allLists rearranged, the algorithm is broken. I'm working on a fix, though.

aList = [1, 2, 3, 4, 5]
bList = [4, 5, 6, 7, 8]
cList = [7, 8, 9, 10, 11]
dList = [100, 200, 300, 400]
eList = [100, 600, 700]
allLists = [dList, cList, aList, bList, eList]
 
 
resultList = []
while allLists:
    listCount = len(allLists)
    removeList = []
    for i in range(listCount - 1):
        if (set(allLists[0]) & set(allLists[i+1])):
            removeList.append(allLists[i+1])
 
            allLists[0] = list(set(allLists[0]).union(set(allLists[i+1])))
 
    if allLists:
        tempList = allLists.pop(0)
        resultList.append(tempList)
 
    for tempList in removeList:
        if tempList in allLists:
            allLists.remove(tempList)
 
print resultList

[[400, 600, 100, 200, 700, 300], [4, 5, 6, 7, 8, 9, 10, 11], [1, 2, 3, 4, 5]]

[bartonc]

Here it is a bit simplified. But, if you'll notice, with the order of allLists rearranged, the algorithm is broken. I'm working on a fix, though.

aList = [1, 2, 3, 4, 5]
bList = [4, 5, 6, 7, 8]
cList = [7, 8, 9, 10, 11]
dList = [100, 200, 300, 400]
eList = [100, 600, 700]
allLists = [dList, cList, aList, bList, eList]
 
 
resultList = []
while allLists:
    listCount = len(allLists)
    removeList = []
    for i in range(listCount - 1):
        if (set(allLists[0]) & set(allLists[i+1])):
            removeList.append(allLists[i+1])
 
            allLists[0] = list(set(allLists[0]).union(set(allLists[i+1])))
 
    if allLists:
        tempList = allLists.pop(0)
        resultList.append(tempList)
 
    for tempList in removeList:
        if tempList in allLists:
            allLists.remove(tempList)
 
print resultList

[[400, 600, 100, 200, 700, 300], [4, 5, 6, 7, 8, 9, 10, 11], [1, 2, 3, 4, 5]]

Just to show you my thinking: Here is a function that is just a bit simpler than the last and still works the same. Eventually this will become a recursive function...

def ListUnionFinder(someLists, aList = []):
    resultList = []
    while someLists:
        tempList = someLists.pop(0)
        listCount = len(someLists)
        removeList = []
        for i in range(listCount - 1):
            if (set(tempList) & set(someLists[i+1])):
                removeList.append(someLists[i+1])
 
                tempList = list(set(tempList).union(set(someLists[i+1])))
 
        resultList.append(tempList)
 
        for tempList in removeList:
            if tempList in someLists:
                someLists.remove(tempList)
 
    print resultList
 
ListUnionFinder(allLists)