Question

I am trying to loop through column in an access table using Python. The column I have is sorted ascending.

I am trying to loop though the rows and when the value in the column changes, I want to get count of of all those values. In the example column below, the first group of values I want to count are the M1‘s. When the next row changes to M21, I want to count the M21‘s until it changes to M23b and so on.

I don’t want to use an if/else statement, because there are a few hundred different possible values. I played around with the groupby function in the itertools module, but I haven’t been able to solve the syntax to work in my example. I also tried a silly loop doing something like if row != row.next(): do_something but that blew up in my face. If anyone can suggest a work-around or show me a sample script that will do this for me, I’d appreciate it.

Example Column:

M1
M1
M1
M21
M21
M23b
M23b
S2
S23b
S23B
O1
O2
O2
O2

Answer 1

If you want to add printing in a loop doing other work, the following may be helpful:

from collections import Counter  # or defaultdict

col_counts = Counter()           # or defaultdict(int)

last_value = object()            # won't show up in table
for row in access_table:
    col_counts[row[field]] += 1
    if row[field] != last_value:
        print(col_counts[last_value])
        last_value = row[field]
    ...
    other_processing()
    ...