How d[key] is getting values of python dictionary in iteration(for loop)

Question

How d[key] is getting dictionary values in for loop? I know the other way to write dictionary code in for loop is:

d = {'a': 1, 'b': 2, 'c': 3} 
for key, values in d.items():
    print (key, 'corresponds to', values)

But I want to know how in below for loop how d[key] is getting values. Is there dictionary values are getting convert to list? Please help me here.

d = {'a': 1, 'b': 2, 'c': 3} 
for key in d:
    print (key, 'corresponds to', d[key])

score 0 · Answer 1 · answered Jan 03 '19 at 07:43

When you simply iterate over a dict like that, you are actually iterating over the keys of the dictionary. For example:

>>> d = {'a': 1, 'b': 2, 'c': 3}
>>> list(d)
['a', 'b', 'c']

Then, d[key] accesses the value at the specified key in the dictionary.

score 0 · Answer 2 · answered Jan 03 '19 at 07:44

0

It' because in the second snippet you are accessing directly the dict (d[key]):

d = {'a': 1, 'b': 2, 'c': 3} 
for key in d:
  print(key) # <-- see the output
  print (key, 'corresponds to', d[key])

d.items() is a kind of helper which returns the pair key, value:

print(d.items()) #=> dict_items([('a', 1), ('b', 2), ('c', 3)])

Something like:

lst = [(1,2), (2,4)]
for k,v in lst:
  print(k, v)

answered Jan 03 '19 at 07:44

iGian

I have another question, in a list x=[1,2,3,4,5,6,7,4,4,3,2,1] how can I get second in last record of 4 using loop. – TARUN PUNETHA Jan 04 '19 at 06:36
@TARUN PUNETHA, I think I don’t completely understand your question. – iGian Jan 05 '19 at 06:35
thanks for help earlier, I was asking to remove duplicates from a list. Sorry for confusion.I searched in stack overflow and I got answer, using set() function duplicates can be removed. – TARUN PUNETHA Jan 07 '19 at 06:45

2 Answers2