Adding each item from one list to each item from another list to third list

user_17318742 0
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Image the following lists:

A = [1,2,3,4]
B = ['A','B','C','D']
C = [10,11,12,13]
D = [100,200,300,400]

I should get the following results: Z = ['1A10100', '2B11200', '3C12300', '4D13400']

I can do this using a lot of empty arrays, do it first using a for loop for A and B than use this new list and append C for each i, etc.

The question is, can this be done in a smarter way. In my real case the lists are 6?

list arrays python
3 Answers

You can use a simple list comprehension:

Z = [''.join(str(x) for x in l) for l in zip(A,B,C,D)]

output: ['1A10100', '2B11200', '3C12300', '4D13400']

If you already have a container for your lists:

lists = [A,B,C,D]
[''.join(str(x) for x in l) for l in zip(*lists)]
user_163434640

Using a list comprehension we can try:

A = [1,2,3,4]
B = ['A','B','C','D']
C = [10,11,12,13]
D = [100,200,300,400]

nums = list(range(0, len(A)))
Z = [str(A[i]) + B[i] + str(C[i]) + str(D[i]) for i in nums]
print(Z)  # ['1A10100', '2B11200', '3C12300', '4D13400']
user_18632290

If the length of each lists are fixed and same length you can simply loop by indices, concatenate them, and then push altogether one-by-one into the result array.

A = [1,2,3,4]
B = ['A','B','C','D']
C = [10,11,12,13]
D = [100,200,300,400]

# Prepare the empty array
result = []

# Concat and insert one-by-one
for i in range(len(A)):
    result.append('{}{}{}{}'.format(A[i], B[i], C[i], D[i]))
    
print(result)

Output:

['1A10100', '2B11200', '3C12300', '4D13400']

There are also another way to concatenate and insert to the result array besides the code above:

  • You can assign a temporary variable to concatenate before inserting:
for i in range(len(A)):
    tmp = str(A[i]) + B[i] + str(C[i]) + str(D[i])
    result.append(tmp)
  • Or you can just put the variables in the inner curly brackets in this way
for i in range(len(A)):
    result.append(f'{A[i]}{B[i]}{C[i]}{D[i]}')
user_146318850
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