Python Multiply Each Item In Sublists By A List

I have a list of sublists, such as this: t = [ [1, 2, 3, 4], [2, 5, 7, 9], [7, 9, 11, 4] ] I want to multiply each of the sublists by a list such that the first item in each sublis

Solution 1:

Actually, numpy makes it easier:

import numpy as np
t = np.array([ [1, 2, 3, 4], [2, 5, 7, 9], [7, 9, 11, 4] ])
multiplier = np.array([0.1, 0.3, 0.5, 0.8])
answer = t * multiplier

Solution 2:

total_result = list()
for v in t:
    result = list()
    for num, mul in zip(v, multiplier):
        result.append(round(num*mul, 2))
    total_result.append(result)

or just one line

total_result = [[round(num*mul, 2) for num, mul in zip(v, multiplier)] for v in t]

total_result

[[0.1, 0.6, 1.5, 3.2], [0.2, 1.5, 3.5, 7.2], [0.7, 2.7, 5.5, 3.2]]

Solution 3:

numpy(Numpy)would handle all this:

import numpy as np
t = np.array([ [1, 2, 3, 4], [2, 5, 7, 9], [7, 9, 11, 4] ])
multiplier = np.array([0.1, 0.3, 0.5, 0.8])

new_t = [e*multiplier for e in t]

Solution 4:

Numpy would probably be the easiest solution, but if you wanted to do without:

t = [[1, 2, 3, 4], [2, 5, 7, 9], [7, 9, 11, 4]]
multiplier = [0.1, 0.3, 0.5, 0.8]

defmult_lists(operator_list, operand_list):
    # Assuming both lists are same length
    result = []
    for n inrange(len(operator_list)):
        result.append(operator_list[n]*operand_list[n])
    return result

multiplied_t = list(map(lambda i: mult_lists(multiplier, i), t)))

map calls the mult_lists function for each item in t, then it is arranged in a list.

Solution 5:

You can use list comprehension:

[[li[i]*multiplier[i] for i in range(len(multiplier))] for li in t]

For clarity, expanded iterative version is:

new_list = []
for li in t:
    new_list.append([li[i]*multiplier[i] for i in range(len(multiplier))])

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