Home / Questions / 102474
Accepted
Alejandro Carrera
Asked: 2020-09-15 16:24:45 +0800 CST 2020-09-15 16:24:45 +0800 CST

How to update values ​​from a dictionary in Python?

  • 772

Suppose I have the following Python dictionary:

 letters= {0: 'a',
 1: 'b',
 2: 'c',
 3: 'd',
 4: 'e',
 5: 'f',
 6: 'g',
 7: 'h',
 8: 'i',
 9: 'j',
 10: 'k',
 11: 'l',
 12: 'm',
 13: 'n',
 14: 'o',
 15: 'p',
 16: 'q',
 17: 'r',
 18: 's',
 19: 't',
 20: 'u',
 21: 'v',
 22: 'w',
 23: 'x',
 24: 'y',
 25: 'z',
 26: ' '}

And I change the order of the keys and values ​​with the following dict comprehension:

encoding = {y:x for x,y in letters.items()}

The next thing I want to do is that, for each letter (key), its value is increased by 3 using the following:

ek= 3

That way, we would have:

'a': 3
'b': 4

and so on.

How can I achieve that without having to do it manually? I would like to put some idea but these two approaches were not successful:

encoding= {sum(ek) for x in encoding.values()}
TypeError: 'int' object is not iterable


encoding.update(sum(ek) in encoding.values())
TypeError: 'int' object is not iterable

Any help will be greatly appreciated. Cheers!

python

1 Answers

  1. Best Answer

    You can do it directly in the creation of encoding, adding the variable

    ek = 3
encoding = {v: k+ek for k, v in letters.items()}

    The built-in function sum receives an iterable and returns the sum of its items by iterating over it. You are passing the values ​​from the dictionary, which are integers, hence the error (you cannot iterate over an integer).

    If you don't want to do the addition on creation encodigyou can use a loop forto modify the 'in-place' values ​​later:

    for key in encoding:
    encoding[key] += ek

    Or using dict.update:

    encoding.update({k: v + ek for k, v in encoding.items()})

    Either way, the output is:

    {'a': 3,
 'b': 4,
 'c': 5,
 'd': 6,
 'e': 7,
 'f': 8,
 'g': 9,
 'h': 10,
 'i': 11,
 'j': 12,
 'k': 13,
 'l': 14,
 'm': 15,
 'n': 16,
 'o': 17,
 'p': 18,
 'q': 19,
 'r': 20,
 's': 21,
 't': 22,
 'u': 23,
 'v': 24,
 'w': 25,
 'x': 26,
 'y': 27,
 'z': 28,
 ' ': 29,}
    • 2