unpacking dictionary in python and getting values

Question

I have this dictionary and I am trying to extract the values

dict = {'distances': array([ 870.99793539]), 'labels': array([2])}

I tried to use

self.printit(**dict)

def printit(distances,labels):         
    print distances
    print labels

but I am getting error

TypeError: printit() got multiple values for keyword argument 'distances'

Answer 1

Why you were getting a TypeError:

When you call a method with self.printit(**somedict), the first argument passed to the function printit is self. So if you define

def printit(distances, labels):

the distances is set to self. Since somedict contains a key called distances, the distances keyword is being supplied twice. That's the why the TypeError was being raised.

---

How to fix it:

Your function

def printit(distances,lables):  

uses a variable named lables, but the dict has a key spelled labels. You probably want to change lables to labels.

---

Add self as the first argument to printit.

def printit(self, distances, labels): 

Calling the first argument self is just a convention -- you could call it something else (though that is not recommended) -- but you definitely do need to put some variable name there since calling

self.printit(...) will call printit(self, ...).

---

For example,

import numpy as np
class Foo(object):
    def printit(self, distances, labels): 
            print distances
            print labels

somedict = {'distances': np.array([ 870.99793539]), 'labels': np.array([2])}
self = Foo()
self.printit(**somedict)

prints

[ 870.99793539]
[2]

---

Answer 2

You had a typo: lables instead of labels. This works fine:

from numpy import array

my_dict = {'distances': array([ 870.99793539]), 'labels': array([2])}

def printit(distances,labels): # changed lables to labels      
    print distances
    print labels # changed lables to labels

printit(**my_dict)

Result:

[ 870.99793539]
[2]
>>>