Python: Loop Dictionary, Two keys at a time

Question

I'm working on a program that requires me to loop a dictionary two keys at a time. Here's a simple representation of my dictionary.

my_dict = {
    'LAP0-1': 146.48,
    'LAP1-1':44.11,
    'LAP2-1':25.54,
    'LAP3-1':75.29,
    'LAP5-2':85.76,
    'LAP6-2':46.87
}

# loop dictionary 1 key at a time
for k,v in my_dict:
    print k + " | " + v;

I know if I had a list, I could loop the items 2 at a time like so:

for i in range(0, len(my_list), 2):
    print my_list[i] + " | " + my_list[i+1];

But is it possible to loop the dictionary two keys at a time?

I want to print out the following in a loop:

LAP0-1 | 146.48 ; LAP1-1 | 44.11
LAP1-1 | 44.11 ; LAP2-1 | 25.54
LAP2-1 | 75.29 ; LAP3-1 | 85.76
LAP5-2 | 85.76 ; LAP6-2 | 46.87

Another solution I thought of but won't for my case is this:

for i in range(0, len(my_list), 2):
    print my_dict[my_list[i]] + " | " my_dict[my_list[i+1]];

where my_list[i] is'LAP0-1' and my_list[i+1] is 'LAP1-1'. It just seems inefficient having to store keep 2 data structures like that. How do I loop a dictionary two keys at a time?

Answer 1

from collections import OrderedDict
from itertools import tee

my_dict = OrderedDict([
    ('LAP0-1', 146.48),
    ('LAP1-1', 44.11),
    ('LAP2-1', 25.54),
    ('LAP3-1', 75.29),
    ('LAP5-2', 85.76),
    ('LAP6-2', 46.87)
])

# pairwise() from Itertools Recipes
def pairwise(iterable):
    "s -> (s0,s1), (s1,s2), (s2, s3), ..."
    a, b = tee(iterable)
    next(b, None)
    return zip(a, b)

for (key1, value1), (key2, value2) in pairwise(my_dict.items()):
    print("{} | {} ; {} | {}".format(key1, value1, key2, value2))

OUTPUT

LAP0-1 | 146.48 ; LAP1-1 | 44.11
LAP1-1 | 44.11 ; LAP2-1 | 25.54
LAP2-1 | 25.54 ; LAP3-1 | 75.29
LAP3-1 | 75.29 ; LAP5-2 | 85.76
LAP5-2 | 85.76 ; LAP6-2 | 46.87