How do I delete specific list items based on repeat values in Python?-CodePudding

I am pretty new to python and am trying to learn how to manipulate lists. This is stumping me and I am sure it is very easy to do without a hundred lines of code with if statements which is the only way I can think to do it.

Setup:

tileNUMS = ['4', '2', '4', '4', '2', '3', '4', '2', '2', '4', '1', '2', '2', '4', '3', '2', '2', '4', '3', '2', '4', '4', '3', '4', '4', '4', '4', '4']

TileList = [tileNUMS[i:i 4] for i in range (0, len(tileNUMS),4)]

Returns:

[['4', '2', '4', '4'], ['2', '3', '4', '2'], ['2', '4', '1', '2'], ['2', '4', '3', '2'], ['2', '4', '3', '2'], ['4', '4', '3', '4'], ['4', '4', '4', '4']]

The two outside numbers are values, and the two inside numbers are position.

What I would like is if the middle two values are repeated i.e. '4', '3' above, then only the last value of that repetition gets added to the list. i.e.

[['4', '2', '4', '4'], ['2', '3', '4', '2'], ['2', '4', '1', '2'], ['4', '4', '3', '4'], ['4', '4', '4', '4']]

After cleaning repeated positions, I want to end up with a list with every position (middle two numbers) from '1', '1' to '4', '4' and the value of that tile as the third item in the list, including 0 as a value if it is not present in the original list. i.e.

[['1', '1', 0], ['1', '2', 0], ['1', '3', 0], ['1', '4', 0], ['2', '1', 0], ... ['4', '4', '4']

I hope this makes sense. Thank you!!

CodePudding user response：

Now that's a unique list manipulation.. Does every "tile" (4 elements list) always has first and last same elements?

Let's assume it does so I will treat each tile as a 3 elements list. I took the liberty to change some more stuff, like using ints , not str to save your data.

I'd recommend dictionaries.

This should put you in a good start:

tile_nums = ['4', '2', '4', '4', '2', '3', '4', '2', '2', '4', '1', '2', '2', '4', '3', '2', '2', '4', '3', '2', '4', '4', '3', '4', '4', '4', '4', '4']

ROW_INDEX_POSITION = 1
COL_INDEX_POSITION = 2
VALUE_POSITION = 0

BATCH_LEN = 4

tile_list = [tile_nums[i: i   BATCH_LEN] for i in range (0, len(tile_nums), BATCH_LEN)]

# dict would allow us to keep a UNIQUED collection which saves the latests values.
only_latest_indexes = dict(((int(tile[ROW_INDEX_POSITION]), int(tile[COL_INDEX_POSITION])), int(tile[VALUE_POSITION])) for tile in tile_list)


result = {}
for i in range(1, BATCH_LEN   1):
    for j in range(1, BATCH_LEN   1):
        result[(i, j)] = only_latest_indexes.get((i, j), 0)
        
print(result)

CodePudding user response：

To just remove duplicates:

>>> set(tuple(x) for x in tile_nums)
{('2', '3', '4', '2'), ('4', '4', '3', '4'), ('4', '2', '4', '4'), ('2', '4', '1', '2'), ('2', '4', '3', '2'), ('4', '4', '4', '4')}

I'd change the values to int types instead of str types, and use tuple objects instead of list objects to hold them, like so:

>>> x = [tuple(int(i)for i in x) for x in tile_nums]
>>> x
[(4, 2, 4, 4), (2, 3, 4, 2), (2, 4, 1, 2), (2, 4, 3, 2), (2, 4, 3, 2), (4, 4, 3, 4), (4, 4, 4, 4)]

if you need to use the numbers as strings later, just convert them.