[Python] How to list a 2d array in a tabular form along with two 1d arrays from which it was...

I'm trying to calculate a 2d variable z = x + y where x and y are 1d arrays of unequal dimensions (say, x- and y-coordinate points on a spatial grid). I'd like to display the result row-by-row in which the values of x and y are in the first two columns and the corresponding value of z calculated from these x and y values are in the third, something like the following for x = [1, 2] and y = [3, 4, 5]:

x y z
1 3 4
1 4 5
1 5 6
2 3 5
2 4 6
2 5 7


The code below works (using lists here, but will probably need numpy arrays later):

import pandas as pd

x = [1, 2]
y = [3, 4, 5]
col1 = []
col2 = []
z = []
for i in range(len(x)):
for j in range(len(y)):
col1.append(x)
col2.append(y[j])
z.append(x+y[j])

df = pd.DataFrame(zip(col1, col2, z), columns=["x", "y", "z"])
print(df)


Just wondering, is there a better way of doing this without using the loop by some combination of meshgrid, indices, flatten, v/hstack, and reshape? The size of x and y will typically be around 100.

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