Accessing values in list in Python

Question

I have a list in the form like this

[(x1,y0,output), (x1,y1,output), (x1,y2,output), (x2,y0,output), (x2,y1,output), (x2,y2,output)]

[(1, 0, 0), (1, 1, 1), (1, 2, 2), (2, 0, 0), (2, 1, 2), (2, 2, 4)]

I would like to get cells in the list with a specific condition.

For example,

I want all of the cells which x = 1

I hope the result is: [(1, 0, 0), (1, 1, 1), (1, 2, 2)]
I want all of the cells which x = 1, y = 2

I hope the result is: [(1, 2, 2)]

How can I do this?

import numpy as np

result = []
for x in np.arange(1, 3, 1):
    for y in np.arange(0, 3, 1):
        res = y * x
        res = (x, y, res)

        result.append(res)

print(result)

duckboycool · Accepted Answer · 2020-05-08 02:42:33Z

2

You could use list comprehension for this. For example, with your given inputs.

>>>[x for x in result if x[0] == 1]
[(1, 0, 0), (1, 1, 1), (1, 2, 2)]
>>>[x for x in result if x[0] == 1 and x[1] == 2]
[(1, 2, 2)]

answered May 8, 2020 at 2:42

duckboycool

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2 Comments

Joanne Over a year ago

How can I get the third value in the cell? For example, the result I get from [x for x in result if x[0] == 1 and x[1] == 2] is [(1, 2, 2)]. How can I get the result only shows the third value -> [2]

duckboycool Over a year ago

@Joanne You could index the x value that's being returned from the iteration. [x[2] for x in result if x[0] == 1 and x[1] == 2] returns [2].

whackamadoodle3000 · Accepted Answer · 2020-05-08 02:42:49Z

1

Try a list comprehension:

listy = [(1, 0, 0), (1, 1, 1), (1, 2, 2), (2, 0, 0), (2, 1, 2), (2, 2, 4)]
list1 = [e for e in listy if e[0]==1]
list2 = [e for e in listy if e[0]==1 and e[1]==2]

You can change the conditions you choose by in that last if part of the list comprehension.

answered May 8, 2020 at 2:42

whackamadoodle3000

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1 Comment

Joanne Over a year ago

How can I get the third value in the cell? For example, the result I get from [e for e in result if e[0] == 1 and e[1] == 2] is [(1, 2, 2)]. How can I get the result only shows the third value -> [2]

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