hstay - 1 year ago 147
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 Source

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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