Problem with a dictionary program....

Dan Perl danperl at rogers.com
Tue Sep 28 22:09:51 CEST 2004


Sorry, my bad.  I didn't pay attention and I mistook the join( ) for an 
append( ) while just copying and pasting.  I've never used join( ) myself so 
it didn't click in my mind.

Dan

"Jeff Shannon" <jeff at ccvcorp.com> wrote in message 
news:10ljg2vl36tb1e at corp.supernews.com...
> Dan Perl wrote:
>
>>>>output = []
>>>>for character in indput:
>>>>  output.append(List[character])
>>>>  print ', '.join(output)
>>>>
>>That print statement is actually wrong in many ways.  It was probably 
>>meant to be something like
>>    print ','.join(List[int(character)])    # List[int(character)], not 
>> output
>>but even that would start with ',' and it would be on multiple lines 
>>(probably not your intention).
>
> No, it wouldn't start with ',' -- you're not parsing that line the same 
> way that Python does. ;)
>
> aString.join(aList) will combine a list of strings into a single string, 
> using the referenced string as "glue" to stick the pieces together.  Thus, 
> when the referenced string is ', ', you'll get "item0, item1, item2".
>
> Python will evaluate the call to ', '.join() *before* it prints anything. 
> The print statement is given the resulting (single) string as its 
> argument.  Indeed, that line could be split into several lines for 
> clarity:
>
>    separator = ', '
>    outputstring = separator.join(output)
>    print outputstring
>
> The point here is that the for loop builds a list of strings (called 
> 'output').  *After* the for loop finishes, then str.join() combines that 
> list into a single string, which is printed.  However, the O.P. has an 
> indentation problem in his code -- he's put the print statement inside his 
> for loop, which means that every intermediate stage of the partially-built 
> output will get printed as well.  All that needs done to fix it is to 
> outdent it one level (as Alex suggested).
>
> Your suggestion ("print ','.join(List[int(character)])"), by the way, will 
> give results that are far different from what you expect.  ;)
>
> >>> List = ['zero', 'one', 'two', 'three']
> >>> print ",".join(List[int('3')])
> t,h,r,e,e
> >>>
>
> You're correctly looking up the word to use for a given digit, but then 
> you're passing that single string (rather than a list) to join(), which 
> works on any sequence (not just lists).  Well, strings are sequences too 
> (a sequence of characters), so join() creates a string with each element 
> (character) of the sequence separated by the specified string (",").
>
> Jeff Shannon
> Technician/Programmer
> Credit International
>
>
>
> 





More information about the Python-list mailing list