Python filtering with "if" does not filter anything?

Question

I have a list containing lists in two dimensions, so for example records[a][b] would be one value in it. There are some criteria that should filter it. I used a combination of "for" and "if" to do so and it worked. Then some additional criteria had to be added that filter out points that have coordinate value, which are in a range of 10*10 units around the currently iterated-over point. However my code compiles but does not do anything and I can't figure out why (as I am still new to Python).

for rec in range(1,len(records)-1):
    for koor in range(1,len(records)-1):
        if records[rec][4]+10 >= records[koor][4] >= records[rec][4]-10 and\
           records[rec][5]+10 >= records[koor][5] >= records[rec][5]-10 and\
           -1.00036 <= records[rec][8] / records[koor][8] <= 1.00036:

What I thought it would do is look for points in the defined area (line 3 & 4) and only let them pass under the condition of line 5. But it lets everything pass. Why is that not working?

Edit: One entry in the form of records[a] looks like this: ['30.12.1899 08:47:00', '7.2.2003 00:00:00', 48.82, 11.2, 4441489.89, 5410519.48, 4, 1.2, 508.55, 0.0, 0.0, 2].

Yes, I do. That was not a problem for the rest of the code, so it should not be of importance here as well. — Homerun_, Mar 16 '17 at 10:43
Use parenthesis to be sure that everything is done in the correct order. — Gauthier Feuillen, Mar 16 '17 at 10:44
@Chris_Rands `x+10 > x > x-10` this is not always the case. it only happens once for every `rec` — Ma0, Mar 16 '17 at 10:46
@Ev.Kounis Yes I misread it completely, deleted the comment straight after, thanks though! — Chris_Rands, Mar 16 '17 at 10:47
Given appropriate input (like `[(0,0,0,0,4,5,0,0,8),(0,0,0,0,4,5,0,0,4)]`) this code _does_ filter out some indices. — Aran-Fey, Mar 16 '17 at 10:50
Well, I do not see why not too, but I put it as a comment to see what happens without it and got the exact same results. — Homerun_, Mar 16 '17 at 11:06

score 0 · Answer 1 · answered Mar 16 '17 at 10:47

0

Try this:

for rec in records[1:-1]:
    for koor in records[1:-1]:
        if rec == koor:
            # handle this some other way
        elif all(20 >= koor[x] - rec[x] + 10 >= 0 for x in [4, 5]) and abs(rec[8] / koor[8]) <= 1.00036:

answered Mar 16 '17 at 10:47

Ma0

15,057
4
35
65

I just saw the `python 2.4` tag. not sure whether `all` existed back then. – Ma0 Mar 16 '17 at 10:52
Sorry, I should have mentioned that more clearly. I have to use Python-2.4.3 in order to use a certain library. Right now the elif line gives me the error: "TypeError: 'int' object has no attribute '__getitem__' " – Homerun_ Mar 16 '17 at 10:55

Python filtering with "if" does not filter anything?

1 Answers1