CODEWITHSUNDEEP
pythonpython-2.7
Crista23
Crista23

Reputation: 3243

Get Dictionary value Python

I have a list of dictionaries in Python and I want to check if an dictionary entry exists for a specific term. It works using the syntax

if any(d['acronym'] == 'lol' for d in loaded_data):
       print "found"

but I also want to get the value stored at this key, I mean d['acronym']['meaning']. My problem is that when I try to print it out Python does not know about d. Any suggestions, maybe how can I get the index of the occurence without looping again through all the list? Thanks!

Upvotes: 0

Views: 193

Answers (5)

glglgl
glglgl

Reputation: 91099

firstone = next((d for d in loaded_data if d['acronym'] == 'lol'), None)

gives you the first dict where the condition applies, or None if there is no such dict.

Upvotes: 0

DSM
DSM

Reputation: 353339

If you know there's at most one match (or, alternatively, that you only care about the first) you can use next:

>>> loaded_data = [{"acronym": "AUP", "meaning": "Always Use Python"}, {"acronym": "GNDN", "meaning": "Goes Nowhere, Does Nothing"}]
>>> next(d for d in loaded_data if d['acronym'] == 'AUP')
{'acronym': 'AUP', 'meaning': 'Always Use Python'}

And then depending on whether you want an exception or None as the not-found value:

>>> next(d for d in loaded_data if d['acronym'] == 'AZZ')
Traceback (most recent call last):
  File "<ipython-input-18-27ec09ac3228>", line 1, in <module>
    next(d for d in loaded_data if d['acronym'] == 'AZZ')
StopIteration

>>> next((d for d in loaded_data if d['acronym'] == 'AZZ'), None)
>>>

You could even get the value and not the dict directly, if you wanted:

>>> next((d['meaning'] for d in loaded_data if d['acronym'] == 'GNDN'), None)
'Goes Nowhere, Does Nothing'

Upvotes: 3

Paulo Bu
Paulo Bu

Reputation: 29804

You can just use filter function:

filter(lambda d: d['acronym'] == 'lol', loaded_data)

That will return a list of dictionaries containing acronym == lol:

l = filter(lambda d: d['acronym'] == 'lol', loaded_data)
if l:
    print "found"
    print l[0]

Don't even need to use any function at all.

Upvotes: 2

RemcoGerlich
RemcoGerlich

Reputation: 31270

any() only gives you back a boolean, so you can't use that. So just write a loop:

for d in loaded_data:
    if d['acronym'] == 'lol':
        print "found"
        meaning = d['meaning']
        break
else:
    # The else: of a for runs only if the loop finished without break
    print "not found"
    meaning = None

Edit: or change it into a slightly more generic function:

def first(iterable, condition):
    # Return first element of iterable for which condition is True
    for element in iterable:
        if condition(element):
            return element
    return None

found_d = first(loaded_data, lambda d: d['acronym'] == 'lol')
if found_d:
    print "found"
    # Use found_d

Upvotes: 0

jonrsharpe
jonrsharpe

Reputation: 122090

If you want to use the item, rather than just check that it's there:

for d in loaded_data:
    if d['acronym'] == 'lol':
        print("found")
        # use d
        break # skip the rest of loaded_data

Upvotes: 0

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