How does one insert a key value pair into a python list?

Question

a = 1
b = 2 

i want to insert a:b into a blank python list

list = []

as

a:b

what is the proper syntax for this, to result in

[(a:b), (c:d)]

?

this is just so I can sort the list by value from least to greatest later

Answer 1

Let's assume your data looks like this:

a: 15
c: 10
b: 2

There are several ways to have your data sorted. This key/value data is best stored as a dictionary, like so:

data = {
    'a': 15,
    'c': 10,
    'b': 2,
}
# Sort by key:
print [v for (k, v) in sorted(data.iteritems())]
# Output: [15, 2, 10]
# Keys, sorted by value:
from operator import itemgetter
print [k for (k, v) in sorted(data.iteritems(), key = itemgetter(1))]
# Output: ['b', 'c', 'a']

If you store the data as a list of tuples:

data = [
    ('a', 15),
    ('c', 10),
    ('b', 2),
]
data.sort() # Sorts the list in-place
print data
# Output: [('a', 15), ('b', 2), ('c', 10)]
print [x[1] for x in data]
# Output [15, 2, 10]
# Sort by value:
from operator import itemgetter
data = sorted(data, key = itemgetter(1))
print data
# Output [('b', 2), ('c', 10), ('a', 15)]
print [x[1] for x in data]
# Output [2, 10, 15]