[Tutor] array and dictionary

[Alan Gauld]

"Dinesh B Vadhia" <dineshbvadhia at hotmail.com> wrote

> Hi!  Say, I've got a numpy array/matrix of the form:
>
> [[1 6 1 2 3]
>  [4 5 4 7 0]...
>  [2 1 0 5 6]]
> 
> I want to create a dictionary of rows (as the keys) mapped 
> to lists of non-zero numbers in that row

Caveat, I dont know about numpy arrays.But assuming they 
act like Python lists

You can get the non zeros with a comprehension

nz = [n for n in row if n != 0]

you can get the row and index using enumerate

for n,r in enumerate(arr):

So to create a dictionary, combine the elements somethng like:

d ={}
for n,r in enumerate(arr):
    d[n] = [v for v in r if v !=0]

I'm sure you could do it all in one line if you really wanted to!
Also the new any() function might be usable too.

All untested....

HTH,

-- 
Alan Gauld
Author of the Learn to Program web site
http://www.freenetpages.co.uk/hp/alan.gauld