Numeric and matlab

[Schüle Daniel]

Hello,

[...]
> 
> I'm sure there are more, but these jump out at me as I'm going.  It 
> seems as if the idx=find() stuff can be done with Numeric.nonzeros(), 
> but you can't index with that, like
> 
> a=Numeric.arange(1,11,1)
> idx=Numeric.nonzeros(a)

import Numeric as N
N.nonzero

without s :)

> a=a[idx]   % doesn't work

i don't know whether arange object overloads __getitem__
like

 >>> class X(object):
...     def __getitem__(self,i):
...             return self.lst[i]
...     def __init__(self):
...             self.lst = [7,5,3,1]
...
 >>> x=X()
 >>> x[0]
7
 >>> x[1]
5
 >>>

or consider

 >>> class List(list):
...     def __getitem__(self,idx):
...             if type(idx) is list:
...                     ret = []
...                     lst = list(self)
...                     return [lst[i] for i in range(len(lst)) if i in idx]
...
 >>> lst=List([1,2,3,4,5])
 >>> lst
[1, 2, 3, 4, 5]
 >>> lst[[0,2]]
[1, 3]
 >>>

if it would overload this would be possible, the normal
python list takes slices

range(0,100)[1:10:2]
s = slice(1,10,2)
range(0,100)[s]

here some ideas for what you tring to do

 >>> nums	# normal python list
[0, 1, 2, 1, 0, 0, 0, 3, 4, 0]
 >>> filter(lambda x: x!=0, nums)
[1, 2, 1, 3, 4]

 >>> [item for item in nums if item !=0 ]
[1, 2, 1, 3, 4]
 >>>

 >>> a=N.arange(0,11,.5)
 >>> filter(lambda x: x!=0, a)
[0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 
7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5]

 >>> [item for item in a if item !=0 ]
[0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 
7.5, 8.0, 8.5, 9.0, 9.5, 10.0, 10.5]

Regards, Daniel