CODEWITHSUNDEEP
pythonvector
urpi
urpi

Reputation: 309

Adding elements to a new created vector in python

I have a vector as follows

vector_partitions = [[4,1,1],[3,2,1],[2,2,2]].

I want to create a new vector by modifying vector_partitions by dividing 6 by each element of each vector element in vector_partitions, so for instance my new vector should be pre_final = [[1.5,6,6], [2,3,6], [3,3,3]].

The code I wrote for this is the following: 

vector_partitions = part(int(x),int(y))

length = len(vector_partitions)

for i in range(0, length):
    length_new_vect = len(vector_partitions[1])
    pre_final = []
    pre_final.extend([int(x)/p for p in vector_partitions[i]])

print(pre_final)

However, I end up getting just the last element of whay my pre_final should be, so I end up getting only the vector [3,3,3]. Does anyone know how I can fix this?

Upvotes: 0

Views: 168

Answers (2)

Sede
Sede

Reputation: 61253

Actually you don't need to use range or extend to do this. Simply use list comprehensions.

>>> vector_partitions = [[4, 1, 1], [3, 2, 1], [2, 2, 2]]
>>> pre_final = [[6/i for i in item] for item in vector_partitions]
>>> pre_final
[[1.5, 6.0, 6.0], [2.0, 3.0, 6.0], [3.0, 3.0, 3.0]]

Upvotes: 1

malbarbo
malbarbo

Reputation: 11177

You are assign [] to pre_final in each iteration and replacing the inserted values. You have to initialize pre_final outside the loop. Also you are using extend that concatenates 2 lists. You need to use append to push the new list in the end of pre_final. This fix your initial code

pre_final = []
for i in range(len(vector_partitions)):
    pre_final.append([6.0 / x for x in vector_partitions[i]])

Upvotes: 1

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