BorrajaX BorrajaX - 1 month ago 11
Python Question

Python: Get values (objects) from a dictionary of objects in which one of the object's field matches a value (or condition)

I have a python dictionary whose keys are strings and the values are objects.

For instance, an object with one string and one int

class DictItem:
def __init__(self, field1, field2):
self.field1 = str(field1)
self.field2 = int(field2)


and the dictionary:

myDict = dict()
myDict["sampleKey1"] = DictItem("test1", 1)
myDict["sampleKey2"] = DictItem("test2", 2)
myDict["sampleKey3"] = DictItem("test3", 3)


Which is the best/most efficient way to get the dictionary entries that have the "field2" field >= 2?

The idea is creating a "sub-dictionary" (a list would do too) only with the entries in which field2 >= 2 (in the example would be like):

{
"sampleKey2": {
"field1" : "test2",
"field2": 2
},
"sampleKey3": {
"field1" : "test3",
"field2": 3
}
}


Is there a better way than walking through all the dictionary elements and check for the condition? Maybe using itemgetters, and lambda functions?

Thank you!

P.S.: I am using Python2.4, just in case it's relevant

Answer

To make a dict from your dict,

subdict = dict((k, v) for k, v in myDict.iteritems() if v.field2 >= 2)
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