[Tutor] dictionaries help

[Alan Gauld]

<davidwilson at Safe-mail.net> wrote

> i would like to understand how dictionaries work.

They work like a lookup table.
You provide a key and lookup the corresponding value
in the dictionary. So to implement a traditional language
dictionary the keys would be words and the values would
be a list of definitions.

You read them by placing the key in square brackets,
or by using the get() method:

> for example:
>>>> my_lst = [{'code': 'aaa', 'name': 'a name'}, {'code': 'bbb', 'name': 
>>>> 'b name'}]

my_lst[0]['code']   -> 'aaa'
my_lst[0].get('code', 0)    -> 'aaa'  or 0 if 'aaa' does not exist as a key

You can write to them using the [] notation too:

my_lst[0]['name'] = 'A new name'      changes the value for name in the 
first dictionary.

>>>> my_code = 'aaa'
> from the above i would like to compare my_code and return the
> dictionary which has code == my_code

Vince has shown you one way, this is another way:

def findDict(value, dictList):
   for dct in dictList:
       if dct.get('code', '') == my_code
          return dct

HTH,


-- 
Alan Gauld
Author of the Learn to Program web site
http://www.alan-g.me.uk/