CODEWITHSUNDEEP
pythondictionaryiteration
Kevin
Kevin

Reputation: 23

Iterate Through a Dictionary Updating Values on the Fly Python3

I am trying to make it so whenever the value in my dictionary is 'A9', the key:value pairs after 'A9' become 'a0' and it iterates all over again until 'a9' which I would then like to change to 'B0', etc.

My expected output:

{'0000': 'A0', '0001': 'A1', '0002': 'A2', '0003': 'A3', '0004': 'A4', '0005': 'A5', '0006': 'A6', '0007': 'A7', '0008': 'A8', '0009': 'A9', '0010': 'a0', '0011': 'a1', '0012': 'a2', '0013': 'a3', '0014': 'a4', '0015': 'a5', '0016': 'a6', '0017': 'a7', '0018': 'a8', '0019': 'a9', '0020':'B0', '0021':'B1'}

My current code:

ustr = (['%.4d' % i for i in range(0, 22)])
d2 = {x:f'A{i+0}' for i, x in enumerate(sorted(set(ustr)))}
print(d2)
for k, v in d2.items():
    print(v)
    if v == 'A9':
        v = {x:f'a{i+0}' for i, x in enumerate(sorted(set(ustr)))}
        print(v)

This output I'm receiving is overriding my dictionary. I know why. I'm telling the if statement to replace all the values of the string with 'a0'. I just don't know how to write the code to specify that after 'A9' that it continues with 'a0'.

Upvotes: 0

Views: 137

Answers (2)

Ralf
Ralf

Reputation: 16505

Python dictionaries are unordered, so there is no concept of "before" that specific key or "after".

The sorting you are doing with {x:f'a{i+0}' for i, x in enumerate(sorted(set(ustr)))} has no effect once the dict is created.

Maybe consider using a OrderedDict (it is in the standard lib).

Note: specific Python implementations (or versions) may keep an iteration order, but it is not garanteed in the language specifications.

Apprently there is a garanteed order starting in Python 3.7:

iter(dictview)

[...]

Changed in version 3.7: Dictionary order is guaranteed to be insertion order.

Upvotes: 0

Brian
Brian

Reputation: 1604

Are you trying to do something like this?

input_dict = {'0000': 'A0', '0001': 'A1', '0002': 'A2', '0003': 'A3', '0004': 'A4', '0005': 'A5', '0006': 'A6', '0007': 'A7', '0008': 'A8', '0009': 'A9', '0010': 'a0', '0011': 'a1', '0012': 'a2', '0013': 'a3', '0014': 'a4', '0015': 'a5', '0016': 'a6', '0017': 'a7', '0018': 'a8', '0019': 'a9', '0020':'B0', '0021':'B1'}

alphabet = ['A', 'B', 'C', 'D', 'E', "..."]
numbers = range(10)

dict(zip(input_dict.keys(), [f"{letter}{num}" for letter in alphabet for num in numbers]))

output: 

>>>
{'0000': 'A0',
 '0001': 'A1',
 '0002': 'A2',
 '0003': 'A3',
 '0004': 'A4',
 '0005': 'A5',
 '0006': 'A6',
 '0007': 'A7',
 '0008': 'A8',
 '0009': 'A9',
 '0010': 'B0',
 '0011': 'B1',
 '0012': 'B2',
 '0013': 'B3',
 '0014': 'B4',
 '0015': 'B5',
 '0016': 'B6',
 '0017': 'B7',
 '0018': 'B8',
 '0019': 'B9',
 '0020': 'C0',
 '0021': 'C1'}

You can add an extra row of A's at the beginning pretty easily. But I wasn't sure if you wanted that or if that was a typo.

Upvotes: 1

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