CODEWITHSUNDEEP
pythonpython-3.xdictionaryfor-loop
Pacool1234
Pacool1234

Reputation: 47

Dictionary does not add new entries

From a tuple of strings, a function that creates a dictionary and adds the index (key) and length of string (value). But, the for loop only adds certain entries (in this case indexes 0 and 2) and can't figure out why.

Code:

def check_horse_winner(tup):
    results=dict()
    for i in tup:
        results[tup.index(i)]=len(i)
    return results
print(check_horse_winner(("HORSE", "HORSE", "HORS", "HORSE")))

Output:

{0: 5, 2: 4}

Upvotes: 3

Views: 398

Answers (6)

Anjo Tadena
Anjo Tadena

Reputation: 56

Dictionary is a mapping of unique keys to values

You are pushing same index in your dict, this line cause the issue "tup.index(i)" because of "HORSE" value it will get the first index for "HORSE".

Try to change the value of your tuple.

anyways you could check https://www.pythonforbeginners.com/dictionary/how-to-use-dictionaries-in-python/

Upvotes: 2

Veens
Veens

Reputation: 43

index() method searches for the given element in a tuple and returns its position.

However, if the same element is present more than once, the first/smallest position is returned.

So in your case tup.index("HORSE") returns 0 as its index every time. Since there are only two unique elements in the tuple you passed, the return dict has only 2 key-value pairs

Upvotes: 0

CoderCharmander
CoderCharmander

Reputation: 1910

There are same elements in this tuple. index returns the first element's index - so, your program does this:

  1. Start the first iteration - i is "HORSE", index returns 0.
  2. The second iteration - i is "HORSE" again, index will return the first occurrence of it, which is 0 again.

And this goes all the way - except for "HORS" (I think it is just a mistake).

The solution:

Loop over indices rather than the tuple itself, like this:

for i in range(len(tup)):
    results[i] = len(tup[i])

Upvotes: 0

AKX
AKX

Reputation: 169397

There are duplicate values in tup, and .index() returns the first.

Sounds like you want

words = ("HORSE", "HORSE", "HORS", "HORSE")
index_to_length = {
  i: len(w)
  for (i, w)
  in enumerate(words)
}
print(index_to_length)

Upvotes: 2

Sociopath
Sociopath

Reputation: 13426

tup.index(i) will always give you index of first entry in tuple.

As you have same element thrice and dict can not take duplicate keys, it's replacing the same

You can do :

def check_horse_winner(tup):
    results=dict()
    for i,j in enumerate(tup):
        results[i]=len(j)
    return results
print(check_horse_winner(("HORSE", "HORSE", "HORS", "HORSE")))

Alternative:

print({j:len(i) for j,i in enumerate(("HORSE", "HORSE", "HORS", "HORSE"))})

Upvotes: 1

Rakesh
Rakesh

Reputation: 82805

Use enumerate

Ex:

def check_horse_winner(tup):
    results=dict()
    for i, v in enumerate(tup):
        results[i]=len(v)
    return results
print(check_horse_winner(("HORSE", "HORSE", "HORS", "HORSE")))
# --> {0: 5, 1: 5, 2: 4, 3: 5}

Upvotes: 2

Related Questions