Re: Building and accessing an array of dictionaries
On 2014-01-16, Mark Lawrence wrote:
> On 16/01/2014 09:48, Chris Angelico wrote:
>> On Thu, Jan 16, 2014 at 8:41 PM, Sam wrote:
>>> I would like to build an array of dictionaries. Most of the dictionary
>>> example on the net are for single dictionary.
>>>
>>> dict = {'a':'a','b':'b','c':'c'}
>>> dict2 = {'a':'a','b':'b','c':'c'}
>>> dict3 = {'a':'a','b':'b','c':'c'}
>>>
>>> arr = (dict,dict2,dict3)
>>>
>>> What is the syntax to access the value of dict3->'a'?
>>
>> Technically, that's a tuple of dictionaries
>
> For the benefit of lurkers, newbies or whatever it's the commas that
> make the tuple, not the brackets.
In _that_ example, yes. There are other cases where it's the
brackets (sort of):
foo('a','b','c')# three separate string objects are passed
foo(('a','b','c')) # a single tuple object is passed
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Re: Building and accessing an array of dictionaries
On 16/01/2014 09:48, Chris Angelico wrote:
On Thu, Jan 16, 2014 at 8:41 PM, Sam wrote:
I would like to build an array of dictionaries. Most of the dictionary example
on the net are for single dictionary.
dict = {'a':'a','b':'b','c':'c'}
dict2 = {'a':'a','b':'b','c':'c'}
dict3 = {'a':'a','b':'b','c':'c'}
arr = (dict,dict2,dict3)
What is the syntax to access the value of dict3->'a'?
Technically, that's a tuple of dictionaries
For the benefit of lurkers, newbies or whatever it's the commas that
make the tuple, not the brackets.
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what you can do for our language.
Mark Lawrence
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Re: Building and accessing an array of dictionaries
- Original Message -
> I would like to build an array of dictionaries. Most of the
> dictionary example on the net are for single dictionary.
>
> dict = {'a':'a','b':'b','c':'c'}
> dict2 = {'a':'a','b':'b','c':'c'}
> dict3 = {'a':'a','b':'b','c':'c'}
>
> arr = (dict,dict2,dict3)
>
> What is the syntax to access the value of dict3->'a'?
>
> Thank you.
>
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> https://mail.python.org/mailman/listinfo/python-list
>
Hi,
arr = (dict,dict2,dict3)
builds a tuple.
If you want to build a (ordered) List, which is the closest type to array
(arrays don't exists in python), you may write
myList = [dict, dict2, dict3]
you can access 'a' by writing
myList[2]['a']
Additionally:
myList[0] -> 1st element
myList[-1] -> last element
myList[3:] -> list of elements of myList from the the 4th element to the last
Accessing a list element or a dictionary value is done through the same
operator []. That can be confusing at the very beginning, you'll get used to it
eventually.
JM
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Re: Building and accessing an array of dictionaries
Sam writes:
> I would like to build an array of dictionaries. Most of the
> dictionary example on the net are for single dictionary.
>
> dict = {'a':'a','b':'b','c':'c'}
> dict2 = {'a':'a','b':'b','c':'c'}
> dict3 = {'a':'a','b':'b','c':'c'}
>
> arr = (dict,dict2,dict3)
>
> What is the syntax to access the value of dict3->'a'?
This isn't a special case.
arr[2] to get the dictionary
arr[2]['a'] to get the value in the dictionary
'a' in arr[2] to find if there is such a key
arr[2].get('a') to get the value or None if the key isn't there
arr[2].get('a', 'd') to get a value even if the key isn't there
help(dict.get)
for key in arr[2]:
# to iterate over the keys
The exact same mechanisms are used no matter where you get the
dictionary from.
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Re: Building and accessing an array of dictionaries
On Thu, Jan 16, 2014 at 8:41 PM, Sam wrote:
> I would like to build an array of dictionaries. Most of the dictionary
> example on the net are for single dictionary.
>
> dict = {'a':'a','b':'b','c':'c'}
> dict2 = {'a':'a','b':'b','c':'c'}
> dict3 = {'a':'a','b':'b','c':'c'}
>
> arr = (dict,dict2,dict3)
>
> What is the syntax to access the value of dict3->'a'?
Technically, that's a tuple of dictionaries, and you may want to use a
list instead:
lst = [dict, dict2, dict3]
Like any other list or tuple, you can reference them by their indices:
lst[2] is dict3
lst[2]['a'] is dict3['a']
Hope that helps!
ChrisA
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Building and accessing an array of dictionaries
I would like to build an array of dictionaries. Most of the dictionary example
on the net are for single dictionary.
dict = {'a':'a','b':'b','c':'c'}
dict2 = {'a':'a','b':'b','c':'c'}
dict3 = {'a':'a','b':'b','c':'c'}
arr = (dict,dict2,dict3)
What is the syntax to access the value of dict3->'a'?
Thank you.
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