[Tutor] Iterating two one dimensional lists to create a multidemsional array

Kent Johnson kent37 at tds.net
Sat Oct 11 05:59:19 CEST 2008

On Fri, Oct 10, 2008 at 10:45 PM, S Potter <f8lcoder at hotmail.com> wrote:
> OK I'm still new to the python list / array deal. I'm having problems with
> something very simple that I could accomplish in C++ but
> for some reason I'm not grasping it python.
> Here is my example psuedo code:
> I have two lists:
> items = ['roses','violets','sugar','so']
> and
> attributes = ['red','blue','sweet','you']
> I have a variable:
> action = 'are'
> From the above lists I would like to populate a multi dimensional array that
> would be like this;
> poem ={ ['roses','are red'],
>               ['violets','are blue'],
>               ['sugar','are sweet']
>               ['so','are you'] }

The zip() function is handy for processing multiple lists in parallel.
List comprehensions are handy for processing lists by item. Together
they make short work of this:

In [5]: items = ['roses','violets','sugar','so']

In [6]: attributes = ['red','blue','sweet','you']

In [7]: zip(items, attributes)
Out[7]: [('roses', 'red'), ('violets', 'blue'), ('sugar', 'sweet'),
('so', 'you')]

In [8]: [ [item, 'are '+attribute] for item, attribute in zip(items,
attributes) ]
[['roses', 'are red'],
 ['violets', 'are blue'],
 ['sugar', 'are sweet'],
 ['so', 'are you']]


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