How do I print out every other key in a dictionary?-CodePudding

Given:

d = {'c': 3, 'b': 2, 'a': 1, 'd': 4, 'e': 5}
sorted_dict = d.keys()
sorted_dict = sorted(sorted_dict)

for key in sorted_dict:
    print(key)

How do I make it so that it outputs every other key. Right now it outputs:

a
b
c
d
e

but I want it to output:

a
c
e

CodePudding user response：

Python provides "slicing" for very powerful and elegant solutions to problems like this. It's too big a topic to fully explain here but lot's of information all over the net on this core topic, here's a suggestion: https://www.pythontutorial.net/advanced-python/python-slicing/

To solve your specific problem:

d = {'c': 3, 'b': 2, 'a': 1, 'd': 4, 'e': 5}
sorted_dict = d.keys()
sorted_dict = sorted(sorted_dict)

for key in sorted_dict[::2]:
    print(key)

The [::2] here specifies that you want to take all of the sorted list from start to finish but in steps of 2 (ie. every other element)

Incidentally, you can dispense with the for loop and just print your list slice!..

d = {'c': 3, 'b': 2, 'a': 1, 'd': 4, 'e': 5}
sorted_dict = d.keys()
sorted_dict = sorted(sorted_dict)

print(sorted_dict[::2])

['a', 'c', 'e']

CodePudding user response：

sorted_dict = d.keys()
sorted_dict = sorted(sorted_dict)
for key in range(len(sorted_dict),2): print(key)

CodePudding user response：

Let d be the dictionary to print alternating rows on.

d = {'c': 3, 'b': 2, 'a': 1, 'd': 4, 'e': 5}
d = dict(sorted(d.items()))

Dictionaries are sequences, just like lists. Similar techniques can be used for both to keep alternating entries:

for i, key in enumerate(d.keys()):
    if i % 2 == 0:
        print(key)

Or:

for key in list(d.keys())[::2]:
    print(key)