How to extract dict values and set as int variable?-CodePudding

What I want to do is to extract the value of a dictionary to do calculations with it. My dictionary only has one value. But I'm not able to do calculations ( -*/) with dictionary values and I don't find a way to assign the value to an int variable.

a = {'number': 5}
b = a.values()
c = b*3
print(c)

The code produces the error:

TypeError: unsupported operand type(s) for *: 'dict_values' and 'int'

CodePudding user response：

a.values() returns all the values of the dictionary as a dict_values.

Of course, in your case that's only one value, but it's still in that form.

One thing that would work in this case:

a = {'number': 5}
b = a.values()
c = list(b)[0]*3
print(c)

The dict_values itself is a so-called view of the values of the dictionary, for reasons that are a bit too complicated to go into here - but as a result they cannot be indexed directly, so c = b[0]*3 wouldn't work either.

Instead, the dict_values is cast into (forced into a certain type) a list, and the list can be indexed, so list(b)[0]*3 takes the list of values, select the first ([0]) element, and multiplies that by 3.

But what makes more sense:

a = {'number': 5}
b = a['number']
c = b*3

This just uses the dictionary as intended and selects the 'number' value by indexing the dictionary with the key a['number'].

Or:

a = {'number': 5}
b = list(a.values())
c = [x*3 for x in b]

Since the dictionary could have more than one value, you could also take the list of values and multiply each element by 3 individually. But the result would have to be another collection, like this list.

CodePudding user response：

Also, if you do not want to use list or list comprehension you can simply use:

a = {'number': 5}
for x in a.values():
   b=int(x)
c = b*3

Or as I commented:

a = {'number': 5}
b = a['number']
c = b*3