How to add values of keys in dictionaries from input in python

Question

I'm very new to python and am trying to figure out a way to access dictionaries from an input and then add values of similar keys in the dictionaries, then print the resulting value from adding those similar key values. The bad code I have now is:

p = {  
    "charge" : 1,  
    "energy": 938,  
    "spin": 1/2,  
}  
n = {  
    "charge" : 0,  
    "energy": 940,  
    "spin": 1/2,  
}  
e = {  
    "charge": -1,  
    "energy": 0.511,  
    "spin": 1/2,  
}  
x = input("First particle:")  
y = input("Second particle:")  
tcharge = x.get("charge")+y.get("charge")  
tenergy = x.get("energy")+y.get("energy")  
tspin = x.get("spin")+y.get("spin")  
print(tcharge)  
print(tenergy)  
print(tspin)

Does this answer your question? [Convert a String representation of a Dictionary to a dictionary?](https://stackoverflow.com/questions/988228/convert-a-string-representation-of-a-dictionary-to-a-dictionary) — Montgomery Watts, Jan 01 '21 at 05:35
look at this example from yesterday and see if it helps -- https://stackoverflow.com/questions/65519305/how-can-i-add-multiple-dictionaries-to-a-key-inside-a-main-dictionary-example-i/65521935#65521935 — Joe Ferndz, Jan 01 '21 at 05:49
Study python. Use python's features for OO design, i.e. use classes. `class Particle` and make `charge`, `energy` and `spin` instance attributes. In case you don't need any methods you can use named tuples or dataclasses — Pynchia, Jan 01 '21 at 06:06
Does this answer your question? [How to get the value of a variable given its name in a string?](https://stackoverflow.com/questions/9437726/how-to-get-the-value-of-a-variable-given-its-name-in-a-string) — Georgy, Jan 02 '21 at 11:29
Hint: See how you already use the string `"charge"` in order to figure out which piece of information to get out of the dictionary? What if you *used the same technique* to use a string to figure out which dictionary to get? I.e., put them in a dictionary as well? — Karl Knechtel, Jul 05 '22 at 00:58

score 2 · Accepted Answer · answered Jan 01 '21 at 05:37

Use a dictionary to store the names of the particles and their descriptions. Your inputs are strings so the keys of the dictionary should be strings. The values in the dictionary are the dictionaries you've created:

particle = {}
particle['p'] = {  
    "charge" : 1,  
    "energy": 938,  
    "spin": 1/2,  
}  
particle['n'] = {  
    "charge" : 0,  
    "energy": 940,  
    "spin": 1/2,  
}  
particle['e'] = {  
    "charge": -1,  
    "energy": 0.511,  
    "spin": 1/2,  
}  
x = input("First particle:")  
y = input("Second particle:")  
tcharge = particle[x]['charge'] + particle[y]['charge']
tenergy = particle[x]['energy'] + particle[y]['energy']
tspin = particle[x]['spin'] + particle[y]['spin']
print(tcharge)  
print(tenergy)  
print(tspin)

How to add values of keys in dictionaries from input in python

1 Answers1