Case-insensitive comparison of two lists

问题

I have 2 lists. The first is list_A = ['Sasi', 'Babu', 'kuttapppan', 'mathayi'] and my second list is list_B = ['Raman', 'Kesavan', 'sasi', 'unni', 'Kuttappan'].

I want to compare these two lists and identify the values which are duplicated in the second list regardless of if it starts with a capital letter or a lowercase letter. I've tried the following method:

if not [name for name in list_A if name in list_B]:
     print name

But it is not working as expected.

回答1:

#Might be better if we are dealing with huge lists.  

list_A = ['Sasi', 'Babu', 'kuttapppan', 'mathayi']
list_B = ['Raman', 'Kesavan', 'sasi', 'unni', 'Kuttappan'].

d = [x.lower() for x in list_A] # make dict of list with less elements  
for m in list_B:  # search against bigger list  
    if m.lower() in d: print(m)

回答2:

Try using sets. The difference set operation will return unique elements to set abc in the following example. Common elements can be obtained using the intersection set operation

abc = [i.lower() for i in ["a","b","c"]]
bcd = [i.lower() for i in ["b","c","d"]]

print set(abc).difference(set(bcd)) 
print set(abc).intersection(set(bcd))

回答3:

First, convert each element in each list to lowercase with lower(). Then, the easiest way to compare duplicates is with set operations. You can combine these steps with a set comprehension:

list_A = ['Sasi', 'Babu', 'kuttapppan', 'mathayi']
list_B = ['Raman', 'Kesavan', 'sasi', 'unni', 'Kuttappan']
list_A = {item.lower() for item in list_A}
list_B = {item.lower() for item in list_B}

Then use intersection of sets:

copies = list_A & list_B

回答4:

Actually you can make this in just one list comprehansion:

list_A = ['Sasi', 'Babu', 'kuttappan', 'mathayi']
list_B = ['Raman', 'Kesavan', 'sasi', 'unni', 'Kuttappan', 'SaSi']

duplicated = [B for B in list_B if B.lower() in (x.lower() for x in list_A)]
print(duplicated)

This way it returns the original values while comparing the lowercased. Using sets will return the lowercased values and will delete all duplicated values in list_B.

来源：https://stackoverflow.com/questions/33643757/case-insensitive-comparison-of-two-lists

标签

python

list

comparison