hstay hstay - 1 month ago 5
Python Question

Add tuple to a list of tuples

How can I sum a tuple to a list of tuples such as:

>>> a = [(0, 1, 2), (3, 4, 5), (6, 7, 8)]
>>> b = (10, 20, 30)


the result being:

>>> c
[(10, 21, 32), (13, 24, 35), (16, 27, 38)]


I know this can be easily solved with numpy:

>>> import numpy
>>> c = numpy.add(a, b).tolist()
>>> c
[[10, 21, 32], [13, 24, 35], [16, 27, 38]]


but I'd rather avoid numpy.

Answer

one-liner using nested list comprehensions and the magic zip to interleave the fixed b triplet to add to the iterating element of a, no numpy needed:

a = [(0, 1, 2), (3, 4, 5), (6, 7, 8)]
b = (10, 20, 30)

c = [tuple([i+j for i,j in zip(e,b)]) for e in a]
print(c)

result:

[(10, 21, 32), (13, 24, 35), (16, 27, 38)]

EDIT: you could drop the tuple conversion if not needed:

c = [[i+j for i,j in zip(e,b)] for e in a]
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