Python list and dictionary

Question

How do I access dictionaries inside a list?

c = [{'team':2000,'name':'a'}, {'team':3000,'name':'b'}]
values = []
for key, value in c.iteritems():
 values.append((key, value))
 print values

I tried accessing the list using iteritems but I got an error specifying list does not have iteritems. Then, I tried using a for loop but I still get an error specifying list indices must be integers.

• Daniil Ryzhkov: @MoonCheesez he's using python 2.x, obviously
• Moon Cheesez: @DaniilRyzhkov my bad, didn't notice the print statement and was too fast to judge. @Bala could you include the code you used which gave you the error "list indices must be integers"?
• Dean Christian Armada: What is your desired output on your problem?
• Bala: Hey thanks I got it.

Answer 1

I'm not sure what your desired output is, but the problem is that c is a list() of dict()s, not a dict(). So if you want to loop over every key and value in each dict in the list, you need two loops:

In [85]: for dictionary in c:
 ....: for key, value in dictionary.iteritems():
 ....: values.append((key, value))
 ....: print values
 ....:
[('name', 'a')]
[('name', 'a'), ('team', 2000)]
[('name', 'a'), ('team', 2000), ('name', 'b')]
[('name', 'a'), ('team', 2000), ('name', 'b'), ('team', 3000)]

You can also simplify this with a list comprehension:

In [96]: for dictionary in c:
 values.extend((key, value) for key, value in dictionary.iteritems())
 ....:
In [97]: values
Out[97]: [('name', 'a'), ('team', 2000), ('name', 'b'), ('team', 3000)]

Or, simplify it even further, as list.extend() can take any iterable:

In [112]: for dictionary in c:
 values.extend(dictionary.iteritems())
 .....:
In [113]: values
Out[113]: [('name', 'a'), ('team', 2000), ('name', 'b'), ('team', 3000)]

And, lastly, we can populate values with a single line of code using itertools.chain(), which basically "flattens" multiple iterables into a single iterable (thanks @lvc!):

In [114]: from itertools import chain
In [115]: values = list(chain.from_iterable(d.iteritems() for d in c))

• Will: Thanks! Love your name, btw, that's a nickname of mine ;)
• lvc: You can simplify it even further by using the tuples from iteritems directly, rather than unpacking and repacking them - values.extend(dictionary.iteritems()). With itertools, you can then: values = list(chain.from_iterable(d.iteritems() for d in c)).
• Daniil Ryzhkov: values.extend(dictionary.iteritems()) does same effect

Answer 2

Try this:

c = [{'team':2000,'name':'a'}, {'team':3000,'name':'b'}]
values = []
for row in c: 
 for key, value in row.iteritems():
 if key == 'name': 
 values.append((key, value))
print(values)
# gives this
# [('name', 'a'), ('name', 'b'),]

• Bala: Hi will when i run this code getting syntax error in print values.can you help me to get rid of this error.And also I want my output should print only name. eg. name:a name:b
• Merlin: @Bala Did this solve it? If so, mark answer as correct

Answer 3

"c" is not a dictionary therefore iteritems() will not work. Iterate through the list first to isolate the dictionaries.

>>> c = [{'team':2000,'name':'a'}, {'team':3000,'name':'b'}]
... for i in c:
... for k,v in i.items():
... print "key : "+str(k)+' *** '+ "value : "+str(v)
... key : name *** value : a
... key : team *** value : 2000
... key : name *** value : b
... key : team *** value : 3000