[Tutor] Saving and loading data to/from files

[Daryl G]

Thanks Roeland!
Thats what I needed.
I should have thought of that; NameInfo[0]['first']. Ah well, I was
working on this part late last night anyway

Thanks for everyones help!

Daryl



>From: Roeland Rengelink <r.b.rigilink@chello.nl>
>To: Daryl G <gman_95@hotmail.com>
>CC: tutor@python.org
>Subject: Re: [Tutor] Saving and loading data to/from files
>Date: Mon, 04 Jun 2001 08:40:39 +0200
>
>Hi Daryl,
>
>Daryl G wrote:
> >
> > Ok, I figured out the dictionary problem
> > Change the print statement
> > for record in NameInfo:
> >
> >     print "%-15.15s %-15.15s %s" % (record['first'], record['last'],
> > record['phone'])
> >
> > now I don't get that error, however I am having difficulty in figuring 
>out
> > how to add data to the dictionary.
> > This seems to be a sequence directory because of the brackets, correct? 
>Plus
> > in some of my attempts I get a TypeError loop non-sequence
> > Accessing the values inside is different then a non-sequence 
>directionary.
> > Any insight?
> >
>
>NameInfo is a list (sequence). Each element in this list is a
>dictionary.
>
>The trick is to know when you are dealing with the list, and when you're
>dealing with an item (a dictionary in this case) in the list. Just some
>examples to help you on your way:
>
>Here a two-element list of dictionaries is build
>
>NameInfo = [
>     {'first': 'Guido', 'last': 'van Rossum', 'phone': '703-555-1234'},
>     {'first': 'Eric', 'last': 'Idle', 'phone': '212-555-5346'}]
>
>You can access a list-element by indexing with an integer, i.e the first
>element with:
>
>print "%(first)-15.15s %(last)-15.15s %s" % NameInfo[0]
>Guido      van Rossum    703-555-1234
>
>(Maybe you're surprised that the first item in a list has index 0. Think
>of it as an offset)
>
>You can add a new element using something like:
>
>NameInfo.append({'first':'Basil', 'last':'Fawlty',
>'phone':'111-222-33333'}
>
>You can change an element by replacing it with a new dictionary
>
>NameInfo[0] = {'first':'Tim', 'last':'Peters', 'phone':'333-111-22222'}
>
>You can also address items inside each dictionary, for example
>
>print NameInfo[1]['first']
>Eric
>
>(i.e. get the second item in the list and from that item het the value
>of 'first')
>
>Use that to add some info to a dict
>
>NameInfo[2]['birth'] = '01 Apr 1933'   # Date of birth for Basil Fawlty
>
>
>The summary:
>
>Lists are indexed with integers.
>Dictionaries are indexed with a key, which can be pretty much anything
>
>List items are added using the_list.append(item)
>Dict items are changed/added using the_dict[key] = value
>
>if you have a list of dicts, you can access an item in a dict with
>
>value = alist[index][key]
>
>which is pretty much equivalent to
>
>record = alist[index]
>value = record[key]
>
>
>Hope this helps,
>
>Roeland Rengelink
>--
>r.b.rigilink@chello.nl
>
>"Half of what I say is nonsense. Unfortunately I don't know which half"

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