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# Python dictionaries

Hey everyone, So I'm learning Python dictionaries and there's a little exercise that blocks me, written below: primes = {1: 2, 2: 3, 4: 7, 7:17,} print(primes[4]) # 7 print(primes[primes[1]]) # 3 print(primes[primes[4]]) # 17 The first one got it, it prints the 4th number on the list but the other ones can't understand why? Tried different numbers and added even '9: 37' to see if the code checked if it's a prime number but the only message I get is Key Error. Hope my message is cleared, Bests,

3 Answers

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your example works
from sympy import isprime
primes = {1: 2, 2: 3, 4: 7, 7:17, 9:37}
print(primes[4]) # 7
print(primes[primes[1]]) # 3
print(primes[primes[4]]) # 17
for k, v in primes.items():
if isprime(v):
print(k, v)

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primes[1]=2 ----------1
primes[2]=3-----------3
primes[3]=4
Now , primes[primes[1]]-------2
from 1 , you substitute the value of primes[1] into 2
you get primes[2] which is 3

+ 1

Ohhhhh right....
print(primes[primes[4]]) is the same saying:
primes[4] = 7
therefore it gives print(primes[7]) # 17
Now I get it Thanks!
@Rohit Thanks for that example, gonna keep it for later. I'm not there yet! ^^'