Explain this Dict comprehension python

Question

dict1={"a":4,"b":2,"A":6}
print({k.lower():dict1.get(k.lower(),0) + dict1.get(k.upper(),0) for k in dict1.keys()})

I copied this code from a youtube video. I couldn't understand the code properly. Please help me to figure it out. I couldn't understand the purpose of 0 in second line.

k.lower():dict1.get(k.lower(),0)

I'm a beginner in python. kindly help me

To return 0 if that key doesn't exist (instead of throwing KeyError) — re-za, Mar 20 '22 at 10:00

score 0 · Answer 1 · answered Mar 20 '22 at 10:03

0

The second parameter is the value parameter, that is , if the key does not exist this will be the value.
In your example, dict1["B"] does not exist. Normally that would cause an error. But because the value parameter is 0, instead of causing an error it pretends that dict1["B"] is 0. Note that this does not change the original dictionary.\

answered Mar 20 '22 at 10:03

Vas

130
10

but ```dict1.get(k.lower()) ``` exist and when i remove 0 ... it throws error .? why? – Muaviya Mar 21 '22 at 09:56
but k.upper() does not exist for "b" – Vas Mar 22 '22 at 12:07

Explain this Dict comprehension python

1 Answers1