Re: find a specified dictionary in a list

[John Machin]

Odd-R. Hogstad wrote (in private e-mail, with scarcely private contents): In comp.lang.python, you wrote: Odd-R. wrote: I have this list: [{'i': 'milk', 'oid': 1}, {'i': 'butter', 'oid': 2},{'i':'cake','oid':3}] All the dictionaries of this list are of the same form, and all the oids are distinct. If I have an oid and the list, how is the simplest way of getting the dictionary that holds this oid? Something like this: def oidfinder(an_oid, the_list): for d in the_list: if d['oid'] == an_oid: return d return None # These are not the oids you are looking for. Thank you, however I was hoping for something even simpler, as I am to use it in a <tal:block tal:define="d python: Sorry, I don't know what <tal:block etc etc means. And I don't know what "even simpler" could mean. Once you have the list and have defined the function, you can simply deploy it wherever you need the value. current_oid = whatever ... current_dict = oidfinder(current_oid, the_list) Is this the only way to do it? What if I know that the oid I am looking for is pressent? Answering the 2nd question first: ignore the possiblility that the oidfinder() will return None i.e. just chill out. Other ways: (a) use a list comprehension inline: current_dict = [d for d in the_list if d['oid'] == current_oid][0] # this is a tad ugly and will blow up if the sought oid is not present -- but that can't happen, can it ? :-) (b) preprocess the weird/baroque/byzantine list that you have got. the_dict = {} for d in the_list:     the_dict[d['oid']] = d then you do this: current_dict = the_dict[current_oid] # Simpler than that it cannot be. Now a couple of questions for you: (1) Have you contemplated that an oid can appear more than once in the list? (2) What in tarnation is an "oid"????? Cheers, John

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