CODEWITHSUNDEEP
pythondictionary
the_martian
the_martian

Reputation: 634

Modify values of python dictionary

Say I have this dictionary:

my_dicts =  {'key1': 'true', 'key2': 'true'}

and I want to replace true with True

How could I do that.

I've tried to do:

for t in my_dicts:
    t.update((k, "True") for k, v in t.items() if v == "true")

But I get this error:

AttributeError: 'str' object has no attribute 'update'

Upvotes: 0

Views: 114

Answers (5)

Dinesh
Dinesh

Reputation: 1245

Another approach is to use json.loads to convert string to bool type.

import json
my_dicts =  {'key1': 'true', 'key2': 'true'}

for key, value in my_dicts.items():
    if value == 'true':
        my_dicts[key] = json.loads(value)

print(my_dicts)

Output:

{'key1': True, 'key2': True}

Upvotes: 1

Rick
Rick

Reputation: 57

Without modifying your code too much, here is my suggestion:

my_dicts =  {'key1': 'true', 'key2': 'true'}

for key in my_dicts:
    if my_dicts[key] == 'true': my_dicts[key] = 'True'

print("After:")
for key, value in my_dicts.iteritems():
    print(key + " = " + my_dicts[key])

Upvotes: 1

Francisco
Francisco

Reputation: 11476

You can use a dict comprehension:

>>> {key: True if value == 'true' else value for key, value in my_dicts.items()}
{'key1': True, 'key2': True}

Other answers mention using dict.update, if you go this route, there's no need to build the complete dictionary again, you just need to replace the keys for which value == 'true':

>>> my_dicts.update({key: True for key, value in my_dicts.items() if value == 'true'})
>>> my_dicts
{'key1': True, 'key2': True}

Upvotes: 2

booleys1012
booleys1012

Reputation: 731

Francisco's answer is good -- it's how i would do it.

For another inline solution that modifies the dictionary inline rather than create a new one (which would be useful if the dictionary is huge):

d.update((k, v if v != 'true' else True) for k,v in d.items())

Upvotes: 2

ShadowRanger
ShadowRanger

Reputation: 155333

As Francisco notes, a dict comprehension will work to make a new dict with replaced keys. You can also just modify the dict in place, either with an explicit loop:

for k, v in my_dicts.items():
    if v == 'true':
        my_dicts[k] = True

or by using the dict comprehension and updating the original dict with the result:

my_dicts.update({k: True if v == 'true' else v for k, v in my_dicts.items()})

The first approach is likely faster in general, since it avoids the temporary dict, and doesn't even try to update keys unless the value is the "true" string you want to replace.

To be clear, it's normally unsafe to modify a dict as you iterate it, so you're excused if you worry about the first loop. But in this case, it's fine; the danger with mutating a dict as you iterate it comes from adding or removing keys, but since every key you set already exists in the dict, you're only updating the value of an existing key (which is safe/legal), not changing the set of keys themselves (which will bite you).

Upvotes: 1

Related Questions