[Tutor] Help on best way to check resence of item inside list

[Dave Angel]

"jarod_v6 at libero.it" <jarod_v6 at libero.it> Wrote in message:
> Dear All
> 
> clubA= ["mary","luke","amyr","marco","franco","lucia", "sally","genevra","
> electra"]
> clubB= ["mary","rebecca","jane","jessica","judit","sharon","lucia", "sally","
> Castiel","Sam"]
> 
> I have a list of names that I would to annotate  in function of presence in
> different clubs:
> 
> my input files is a long file where I have this :
> 
> mary
> luke
> luigi
> jane
> jessica
> rebecca
> luis
> ################################################à
> 
> with open("file.in") as p:
> mit = []
> for i in p:
>    lines =i.strip("\n").split("\t")
>    if  (lines[0] in clubA:
>               G =lines[-1] +["clubA"]
>    else:
>            G = lines[-1] +["no"]  
> mit.append(G)
>   
> 
> for i in mit:
>    if i.strip("\n").split("\t")[0] in clubB:
>          G =lines[-1] +["clubB"]
>    else:
>            G = lines[-1] +["no"]  
>   finale.append(G)
> ###############################################################
> I just wonder if is appropriate to use a loops to check if is present the
> value on a list. Is it the right way? I can use a dictionary because I have
> many repeated names.
> 
> In the end I wan to have
> 
> 
> mary  clubA clubB
> luke clubA
> luigi  no
> Thanks in advance for any help

There are numerous errors in the above code. You should use
 copy/paste, so we don't waste energy identifying errors that
 don't even exist in your actual code. As it stands,  it wouldn't
 even compile. 

But even if you fix the typos and indentation errors and
 initialization errors,  you still have logic errors if you want
 the output you specify. First,  the second loop doesn’t set the
 lines variable at all, but just uses the value from the last
 iteration of the first loop. Second,  even if you untangle that, 
 luigi would end up with two 'no's,  not one.

You don't say what list could have repeats. I don't see any in
 your sample data. You also don't say how they should be treated. 
 For example,  Are all seventeen  mary's in clubA?
 

Now to your specific question.  You aren't using the loops to
 check the lists for a name.  You're quite reasonably using
 'in'.

You can accomplish your apparent goal much more reasonably by
 using a single loop and more complex if elif and
 else.




-- 
DaveA