[MATRIX-SIG] cmp?

[Tom Short]

> select product_id, dept_number, sum(sales-expenses)
> from sales_info
> group by product_id, dept_number
> 
> with result columns
> 
> product_id, dept_number, sum(sales-expenses) for dept&prod

In Yorick, the "where" function is great for this sort of thing:

> a=[1,2,3,4,5]; b=a*10; c=a*100
> idx=where(a==2&b==20)
> write, a(idx), b(idx), c(idx)
        2       20      200

In Python, you can use the same  approach, but it is more complex 
(primarily because the boolean comparisons have to be done with 
functions):

>>> a=array([1,2,3,4,5])
>>> b=10*a
>>> c=100*a
>>> idx = nonzero(where(boolean_and(equal(a,2),equal(b,20)),1,0))
>>> print take(a,idx), take(b,idx), take(c,idx)
2 20 200

- Tom
--------------------------
See the PTI Lightning Photo Gallery: http://www.pti-us.com/pti/consult/dist/photos.htm

_______________
MATRIX-SIG  - SIG on Matrix Math for Python

send messages to: matrix-sig@python.org
administrivia to: matrix-sig-request@python.org
_______________