Question

Problem:

• Trying to evaluate first 4 characters of each item in list.
• If the first 4 chars match another first 4 chars in the list, then append the last three digits to the first four. See example below.

Notes:

• The list values are not hard coded.
• The list always has this structure “####.###”.
• Only need to match first 4 chars in each item of list.
• Order is not essential.

Code:

Grid = ["094G.016", "094G.019", "194P.005", "194P.015", "093T.021", "093T.102", "094G.032"]

Desired Output:

Grid = ["094G.016\019\032", "194P.005\015", "093T.021\102"]

Research:

• I know that sets can find duplicates, could I use a set to evaluate only the 1st 4 chars, would I run into a problem since indexing of sets cannot be done?

• Would it be better to split the list items into the 2 parts. The four digits before the period (“094G”), and a separate list of the three digits after the period (“093”), compare them, then join them in a new list?

• Is there a better way of doing this all together that I’m not realizing?

Answer 1

Here is one straightforward way to do it.

from collections import defaultdict

grid = ['094G.016', '094G.019', '194P.005', '194P.015', '093T.021', '093T.102', '094G.032']
d = defaultdict(list)

for item in grid:
    k,v = item.split('.')
    d[k].append(v)

result = ['%s.%s' % (k, '/'.join(v)) for k, v in d.items()]

Gives unordered result:

['093T.021/102', '194P.005/015', '094G.016/019/032']