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pythonconcatenation

How to concatenate arrays using conditioning in Python?

I have arrays 'a', 'b' and 'c'. I want to create the array 'd' using concatenate() and add a, b or c if they exist.

d = concatenate([a (if a exists),b (if b exists),c (if c exists)])
Solution

  • Try this. If you want your d is a list of list. 

    a = []
b = ["B", "C"]
c = ["A", "C", "D"]

def concatenate(*args):
    return [item for item in args if item]

print(concatenate(a,b,c))

    OUTPUT:

    [['B', 'C'], ['A', 'C', 'D']]

    But if you want just the values of a,b,c in to d:

    a = []
b = ["B", "C"]
c = ["A", "C", "D"]

def concatenate(*args):
    return [item for arr in args for item in arr] 

print(concatenate(a,b,c))

    OUTPUT:

    ['B', 'C', 'A', 'C', 'D']

    The *args is for your function to accept multiple arguments/lists.

    INPUT:

    a = []
b = ["B", "C"]
c = ["A", "C", "D"]
d = ["X", "Z", "E"]
e = ["J", "H", "G"]
f = ["K", "L", "D"]

concatenate(a,b,c,d,e,f)

    OUTPUT:

    ['B', 'C', 'A', 'C', 'D', 'X', 'Z', 'E', 'J', 'H', 'G', 'K', 'L', 'D']