Creating array from two variable function with one variable being an array

Question

As I did in cases zArr and rzArr I want to use function dl(z) to create an array or list dlArr that contains the generated values from dl given z from zArr and rz from rzArr. I tried doing it like this but the syntax is wrong:

dlArr= [(dl(z,rz) for z in zArr & rz in rzArr)]

Relating code for reference:

zArr = np.linspace(0.01, 2.0, 1048)

def dist_integrand(z):
   dist_integrand = 1.0 / np.sqrt(Omegam * (1 + z) ** 3 + Omegal)
   return dist_integrand

def rz(z):
   rz = integrate.quad(dist_integrand, 0, z)
   return rz

rzArr = (rz(z) for z in zArr)

def dl(z,rz):
    dl = (1+z) * rz
    return dl

#!!
dlArr= [(dl(z,rz) for z in zArr & rz in rzArr)]

J_H · Accepted Answer · 2022-06-17 16:26:49Z

1

You want to iterate over a zipped pair of arrays:

... for z, rz in zip(zArr, rzArr)

https://docs.python.org/3/library/functions.html#zip

The zip( ... ) call is generating a sequence of tuples, and then a tuple unpack operation binds the z, rz names to each generated value.

To better see the details of what's going on, try this:

from pprint import pp

pp(list(zip(zArr, rzArr)))

edited Jun 17, 2022 at 16:26

answered Jun 17, 2022 at 16:24

J_H

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3 Comments

Iguananaut Over a year ago

arr1 & arr2 would be an interesting syntactic sugar for zip() though...

J_H Over a year ago

It already has a meaning: take the bitwise AND of the two arguments.

Iguananaut Over a year ago

Not for lists / sequences though. Ditto how bitwise OR was added for dict merging. Not saying it's a good idea, just an interesting one from the OP :)

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