[Tutor] array manipulations

[Alan Gauld]

"NTB" <ntb1088 at gmail.com> wrote 

>  array [['Food 1', 'Nutrient 1', 0.9],
>            ['Food 1', 'Nutrient 2', 0.2],
>            ['Food 2', 'Nutrient 1', 0.55],
>            ['Food 2', 'Nutrient 2', 0.11]]
> 
> into a new array that looks like this:
> 
> array [['Food 1', 0.9, 0.2],
>         ['Food 2', 0.55, 0.11]]
> 

I'd probably use an intermediate dictionary:

>>> a = [['F1','ggh',0.9],['F1','gh',0.5],['f2','dsd',0.7]]
>>> d = {}
>>> for r in a:
...   if r[0] in d: d[r[0]].append(r[2])
...   else: d[r[0]] = [r[0],r[2]]
...
>>> new = [v for k,v in d.items()]
>>> new
[['F1', 0.9, 0.5], ['f2', 0.6999]]
>>>

There may be a more elegant way to handle the if/else 
but its too early to think of one :-)

HTH,

-- 
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/