Like a matrix

[Yazar Yolait]

I have a string of numbers in a file like so:
0 3 23.3 352 45 4
4 45 23 54 4 5.4 .6

I need to average them horizontally and vertically. Horizontally is easy
since I'm reading one line at a time, but how can I do it vertically like 0
and 4, 3 and 45, etc.
I was thinking of a dictionary but how do you add entries to a dictionary,
you can't can you? Like I would add 0 to a dictionary that holds the 0th
column. And then when I get to line 2, I would add 4 to the dictionary
which has the 0th column data.

[Erik Max Francis]

Re: Like a matrix

Yazar Yolait wrote:
[color=blue]
> I have a string of numbers in a file like so:
> 0 3 23.3 352 45 4
> 4 45 23 54 4 5.4 .6
>
> I need to average them horizontally and vertically. Horizontally is
> easy
> since I'm reading one line at a time, but how can I do it vertically
> like 0
> and 4, 3 and 45, etc.[/color]

Why not read it into a list of lists, and then iterate both ways?
[color=blue]
> I was thinking of a dictionary but how do you add entries to a
> dictionary,
> you can't can you?[/color]

Sure you can:
[color=blue][color=green][color=darkred]
>>> d = {}
>>> d[0] = 'zero'
>>> d[/color][/color][/color]
{0: 'zero'}[color=blue][color=green][color=darkred]
>>> d[1] = 'one'
>>> d[/color][/color][/color]
{0: 'zero', 1: 'one'}[color=blue][color=green][color=darkred]
>>> d[10] = {'a': 1, 'b': 2, 'c': 3}
>>> d[/color][/color][/color]
{0: 'zero', 1: 'one', 10: {'a': 1, 'c': 3, 'b': 2}}

--
Erik Max Francis && max@alcyone.com && http://www.alcyone.com/max/
__ San Jose, CA, USA && 37 20 N 121 53 W && &tSftDotIotE
/ \ The price of eternal vigilance is indifference.
\__/ Marshall McLuhan

[Peter Otten]

Re: Like a matrix

Yazar Yolait wrote:
[color=blue]
> I have a string of numbers in a file like so:
> 0 3 23.3 352 45 4
> 4 45 23 54 4 5.4 .6
>
> I need to average them horizontally and vertically. Horizontally is easy
> since I'm reading one line at a time, but how can I do it vertically like
> 0 and 4, 3 and 45, etc.
> I was thinking of a dictionary but how do you add entries to a dictionary,
> you can't can you? Like I would add 0 to a dictionary that holds the 0th
> column. And then when I get to line 2, I would add 4 to the dictionary
> which has the 0th column data.[/color]
[color=blue][color=green][color=darkred]
>>> from __future__ import division
>>> def avg(alist): return sum(alist)/len(alist)[/color][/color][/color]
....[color=blue][color=green][color=darkred]
>>> u = [1,2,3]
>>> v = [3,2,1]
>>> avg(u)[/color][/color][/color]
2.0

So that was the easy part. Now let's create the columns:
[color=blue][color=green][color=darkred]
>>> m, n, o = zip(u, v)
>>> m[/color][/color][/color]
(1, 3)[color=blue][color=green][color=darkred]
>>> n[/color][/color][/color]
(2, 2)[color=blue][color=green][color=darkred]
>>> avg(o)[/color][/color][/color]
2.0[color=blue][color=green][color=darkred]
>>>[/color][/color][/color]

So that wasn't particular hard, now you see it :-)
zip() returns tuples instead of lists, but as you see above that does no
harm.

Peter

[ryan scott]

Re: Like a matrix

Peter Otten wrote:[color=blue]
> Yazar Yolait wrote:
>
>[color=green]
>>I have a string of numbers in a file like so:
>>0 3 23.3 352 45 4
>>4 45 23 54 4 5.4 .6
>>
>>I need to average them horizontally and vertically. Horizontally is easy
>>since I'm reading one line at a time, but how can I do it vertically like
>>0 and 4, 3 and 45, etc.
>>I was thinking of a dictionary but how do you add entries to a dictionary,
>>you can't can you? Like I would add 0 to a dictionary that holds the 0th
>>column. And then when I get to line 2, I would add 4 to the dictionary
>>which has the 0th column data.[/color]
>
>[color=green][color=darkred]
>>>>from __future__ import division
>>>>def avg(alist): return sum(alist)/len(alist)
>>>[/color][/color]
> ...
>[color=green][color=darkred]
>>>>u = [1,2,3]
>>>>v = [3,2,1]
>>>>avg(u)
>>>[/color][/color]
> 2.0
>
> So that was the easy part. Now let's create the columns:
>
>[color=green][color=darkred]
>>>>m, n, o = zip(u, v)
>>>>m
>>>[/color][/color]
> (1, 3)
>[color=green][color=darkred]
>>>>n
>>>[/color][/color]
> (2, 2)
>[color=green][color=darkred]
>>>>avg(o)
>>>[/color][/color]
> 2.0
>
>
> So that wasn't particular hard, now you see it :-)
> zip() returns tuples instead of lists, but as you see above that does no
> harm.
>
> Peter[/color]

As an addition to this post, you could use avg in map to return a list
of your averages.
[color=blue][color=green]
>>map(avg, zip(u,v))[/color][/color]
[2.0, 2.0, 2.0]


Ryan