# [Numpy-discussion] a 'for' loop within another 'for' loop?

Sebastien.deMentendeHorne at electrabel.com Sebastien.deMentendeHorne at electrabel.com
Wed Jul 14 08:41:09 CDT 2004

```I could not resist to propose an other solution:

r = array([0,2,5,6,8])
l = (r[:,NewAxis] + r[NewAxis,:]).flat

-----Original Message-----
From: Hee-Seng Kye [mailto:kyeser at earthlink.net]
Sent: mercredi 14 juillet 2004 4:22
To: numpy-discussion at lists.sourceforge.net
Subject: [Numpy-discussion] a 'for' loop within another 'for' loop?

Hi. I wrote a program to calculate sums of every possible combinations of
two indices of a list. The main body of the program looks something like
this:

r = [0,2,5,6,8]

l = []

for x in range(0, len(r)):

for y in range(0, len(r)):

k = r[x]+r[y]

l.append(k)

print l

1. I've heard that it's not a good idea to have a 'for' loop within another
'for' loop, and I was wondering if there is a more efficient way to do this.

2. Does anyone know if there is a built-in function or module that would do
the above task in NumPy or Numarray (or even in Python)?

I would really appreciate it if anyone could let me know.