CODEWITHSUNDEEP
pythonlistdictionary
user94628
user94628

Reputation: 3731

How to get a value from a dict in a list of dicts

In this list of dicts:

lst = [{'fruit': 'apple', 'qty':'4', 'color': 'green'},
       {'fruit': 'orange', 'qty':'6', 'color': 'orange'},
       {'fruit': 'melon', 'qty':'2', 'color': 'yellow'}]

I want to get the value of the 'fruit' key where the 'color' key's value is 'yellow'.

I tried:

any(fruits['color'] == 'yellow' for fruits in lst)

My colors are unique and when it returns True I want to set the value of fruitChosen to the selected fruit, which would be 'melon' in this instance.

Upvotes: 2

Views: 351

Answers (4)

jonrsharpe
jonrsharpe

Reputation: 122152

If you're certain that the 'color' keys will be unique, you can easily build a dictionary mapping {color: fruit}:

>>> lst = [{'fruit': 'apple', 'qty':'4', 'color': 'green'},
           {'fruit': 'orange', 'qty':'6', 'color': 'orange'},
           {'fruit': 'melon', 'qty':'2', 'color': 'yellow'}]
>>> dct = {f['color']: f['fruit'] for f in lst}
>>> dct
{'orange': 'orange', 'green': 'apple', 'yellow': 'melon'}

This allows you to quickly and efficiently assign e.g.

fruitChosen = dct['yellow']

Upvotes: 2

Adam Smith
Adam Smith

Reputation: 54243

I think filter fits better in this context.

result = [fruits['fruit'] for fruits in filter(lambda x: x['color'] == 'yellow', lst)]

Upvotes: 1

Martijn Pieters
Martijn Pieters

Reputation: 1124988

You could use the next() function with a generator expression:

fruit_chosen = next((fruit['fruit'] for fruit in lst if fruit['color'] == 'yellow'), None)

This will assign the first fruit dictionary to match to fruit_chosen, or None if there is no match.

Alternatively, if you leave out the default value, next() will raise StopIteration if no match is found:

try:
    fruit_chosen = next(fruit['fruit'] for fruit in lst if fruit['color'] == 'yellow')
except StopIteration:
    # No matching fruit!

Demo:

>>> lst = [{'fruit': 'apple', 'qty':'4', 'color': 'green'},{'fruit': 'orange', 'qty':'6', 'color': 'orange'},{'fruit': 'melon', 'qty':'2', 'color': 'yellow'}]
>>> next((fruit['fruit'] for fruit in lst if fruit['color'] == 'yellow'), None)
'melon'
>>> next((fruit['fruit'] for fruit in lst if fruit['color'] == 'maroon'), None) is None
True
>>> next(fruit['fruit'] for fruit in lst if fruit['color'] == 'maroon')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
StopIteration

Upvotes: 3

Cory Kramer
Cory Kramer

Reputation: 118021

You can use a list comprehension to get a list of all the fruits that are yellow.

lst = [{'fruit': 'apple', 'qty':'4', 'color': 'green'},
       {'fruit': 'orange', 'qty':'6', 'color': 'orange'},
       {'fruit': 'melon', 'qty':'2', 'color': 'yellow'}]

>>> [i['fruit'] for i in lst if i['color'] == 'yellow']
['melon']

Upvotes: 4

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