simple way to un-nest (flatten?) list

[Steven D'Aprano]

On Sun, 05 Nov 2006 21:43:33 +0000, djc wrote:

> There is I am sure an easy way to do this, but I seem to be brain dead 
> tonight. So:
> 
> I have a table such that I can do
> 
>   [line for line  in table if line[7]=='JDOC']
> and
>   [line for line  in table if line[7]=='Aslib']
> and
>   [line for line  in table if line[7]=='ASLIB']
> etc
> 
> I also have a dictionary
>   r=  {'a':('ASLIB','Aslib'),'j':('JDOC', 'jdoc')}
> so I can extract values
> r.values()
> [('ASLIB', 'Aslib'), ('JDOC', 'jdoc')]
> 
> I would like to do
> 
> [line for line  in table if line[7] in ('JDOC','jdoc','Aslib','ASLIB')]

What is the purpose of the "if line[7]" bit?



> so how should I get from
> {'a':('ASLIB','Aslib'),'j':('JDOC','jdoc')}
> to
> ('Aslib','ASLIB','JDOC','jdoc')


Assuming you don't care what order the strings are in:

r = {'a':('ASLIB','Aslib'),'j':('JDOC','jdoc')}
result = sum(r.values(), ())

If you do care about the order:

r = {'a':('ASLIB','Aslib'),'j':('JDOC','jdoc')}
keys = r.keys()
keys.sort()
result = []
for key in keys:
    result.extend(r[key])
result = tuple(result)


-- 
Steven.