Python Programming Language :: elegant python style for loops


	elegant python style for loops To step through a list, the python style is avoid an explicit index. But what if the same hidden index is to be used for more than one list for example:- for key,value in listKeys,listValues : newdict[key]=value won't work as it is a tuple of lists, as opposed to a list of tuples. Is there an elegant solution to this? Is there a way to merge lists into a list of tuples to allow moving through multiple lists, or is the for i in range(len(listkeys)): the only solution? Any suggestions? ian.team.pyt@saltmob.com schrieb: > To step through a list, the python style is avoid an explicit index. > But what if the same hidden index is to be used for more than one list > for example:- > for key,value in listKeys,listValues : > newdict[key]=value > won't work as it is a tuple of lists, as opposed to a list of tuples. > Is there an elegant solution to this? Is there a way to merge lists > into a list of tuples to allow moving through multiple lists, or is > the for i in range(len(listkeys)): the only solution? > Any suggestions? for a, b in zip(lista, listb): ... Diez ian.team.pyt@saltmob.com wrote: > To step through a list, the python style is avoid an explicit index. > But what if the same hidden index is to be used for more than one list > for example:- > for key,value in listKeys,listValues : > newdict[key]=value > won't work as it is a tuple of lists, as opposed to a list of tuples. > Is there an elegant solution to this? Is there a way to merge lists > into a list of tuples to allow moving through multiple lists, or is > the for i in range(len(listkeys)): the only solution? > Any suggestions? zip() creates a list of tuples, or better, itertools.izip() lazily creates tuples as you go. Peter - Hide quoted text - ian.team.pyt@saltmob.com wrote: > To step through a list, the python style is avoid an explicit index. > But what if the same hidden index is to be used for more than one list > for example:- > for key,value in listKeys,listValues : > newdict[key]=value > won't work as it is a tuple of lists, as opposed to a list of tuples. > Is there an elegant solution to this? Is there a way to merge lists > into a list of tuples to allow moving through multiple lists, or is > the for i in range(len(listkeys)): the only solution? > Any suggestions? Yes. The builtin function zip does just that: merging separate lists into a list of tuples. See: http://docs.python.org/lib/built-in-funcs.html#l2h-81 Gary Herron On May 10, 4:20 pm, "Diez B. Roggisch" <d@nospam.web.de> wrote: > for a, b in zip(lista, listb): > ... You don't even need the for loop nowadays. Just pass the zipped list to a dictionary constructor thusly: newdict = dict(zip(listKeys,listValues)) Asun thank you everybody....very well answered.....just one question remains.... where do i find documentation on zip ...i was looking for a function like this, but could not even find a relevant list of functions!! On May 10, 6:00 pm, ian.team.pyt@saltmob.com wrote: > thank you everybody....very well answered.....just one question > remains.... > where do i find documentation on zip ...i was looking for a function > like this, but could not even find a relevant list of functions!! ooops...even that was answered. again, thanks On May 10, 6:51 am, ian.team.pyt@saltmob.com wrote: ... > into a list of tuples to allow moving through multiple lists, or is > the for i in range(len(listkeys)): the only solution? > Any suggestions? For the specific case of indexing lists, the following is cleaner than the 'for i in range...' solution above, and works in cases where zipping the lists may not be appropriate: for i, item in enumerate(mylist): print "%s) My item: %s; My other item: %s" % (i, item, my_non_iterable_object.thing_at(i)) -- Ant. ian.team.pyt@saltmob.com a crit : > To step through a list, the python style is avoid an explicit index. > But what if the same hidden index is to be used for more than one list > for example:- > for key,value in listKeys,listValues : > newdict[key]=value newdict = dict(zip(listKeys, listValues))