Python for key, value in dictionary

Question

So as of now this is my code:

for keys, values in CountWords.items():
    val = values
    print("%s: %s \t %s: %s" % (keys, val, keys, val))

When this is printed it will output this the key and its value and then after a space the same thing. What I want to know is if I can get the second %s: %s to select the next key and value from the dictionary.

Be aware that results can differ per python implementation. Dictionary's are not explicitly ordered until python3.7, so referring to the next item could be unambiguous: https://stackoverflow.com/questions/39980323/are-dictionaries-ordered-in-python-3-6/39980744 — acidjunk, Aug 22 '19 at 07:19
It's not clear how you wanted this to work: the second time through the list, should it use the second and third key-value pairs (overlapping adjacent pairs)? Or the third and fourth (iterating in chunks of size 2)? Either way, this is a common problem with a better canonical duplicate. Keep in mind that any "lazy" technique for iterating over a list will generally apply to any iterable, such as a dict's `.items` in 3.x (or `.iteritems` in 2.x). — Karl Knechtel, May 05 '23 at 02:47

score 14 · Answer 1 · edited Aug 07 '21 at 17:33

14

Instead of trying to get next k-v pair, you can keep current k-v pair and use them on the next iteration

d = {'foo': 'bar', 'fiz': 'baz', 'ham': 'spam'}

prev_key, prev_value = None, None

for key, value in d.items():
    if prev_key and prev_value:
        print("%s: %s \t %s: %s" % (prev_key, prev_value, key, value))
    prev_key, prev_value = key, value

fiz: baz     foo: bar
foo: bar     ham: spam

edited Aug 07 '21 at 17:33

Timothy Alexis Vass

2,526
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answered Mar 31 '15 at 13:50

Rafis Gubaidullin

263
2
7

perv should be prev(ious)_key ? – acidjunk Aug 22 '19 at 07:16

score 0 · Answer 2 · answered Mar 31 '15 at 13:12

0

the items() method returns a list of tuple. Inside a for loop, You'are choosing an element one at time, You can't point within the loop the next element.

answered Mar 31 '15 at 13:12

Filadelfo

86
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Is there a way to select two at a time? – willstaff Mar 31 '15 at 13:13
items() returns a list, You can use an index to get the i-th element and then i-th + 1 element, but You must pay attention to the length of the list. – Filadelfo Mar 31 '15 at 13:27

Python for key, value in dictionary

2 Answers2