Python - Check if all elements in a list satisfy an inequality

Question

I have a list T = [[2,5],[4,7],[8,6],[34,74],[32,35],[24,7],[12,5],[0,34]], and i want to check if all elements in each embedded list within T satisfy an inequality.

So far i have:

upper = 10
lower = 0
for n in range(len(T)):
    if all(lower < x < upper for x in T):
        'do something'
    else:
        'do something different'

So if all elements in each T[n] are between 0 and 10, i want to do something and if else then i want to do something else. In the list above T[0],T[1] and T[2] would satisfy the inequality whereas T[3] would not.

Answer 1

You are almost there. Just replace range(len(T)) with T to iterate over the T list and check for the nested elements in the if condition, as follows :

>>> T = [[2,5],[4,7],[8,6],[34,74],[32,35],[24,7],[12,5],[0,34]]
>>> upper = 10
>>> lower = 0
>>> for elem in T:
        if all(lower < x < upper for x in elem):
            print "True", elem
        else:
            print "False", elem


True [2, 5]
True [4, 7]
True [8, 6]
False [34, 74]
False [32, 35]
False [24, 7]
False [12, 5]
False [0, 34]

Answer 2

I would avoid complicated code and go for numpy:

a = np.array(T)

test = (a>0) & (a<10)
#array([[ True,  True],
#       [ True,  True],
#       [ True,  True],
#       [False, False],
#       [False, False],
#       [False,  True],
#       [False,  True],
#       [False, False]], dtype=bool)

test.all(axis=1)
#array([ True,  True,  True, False, False, False, False, False], dtype=bool)

Which you can reuse as a list calling test.any(axis=1).tolist().

Answer 3

Yes, I'd also go for numpy:

import numpy as np

T = [[2,5],[4,7],[8,6],[34,74],[32,35],[24,7],[12,5],[0,34]]
T = np.array(T)
for t in T:
    if np.all(t>0) & np.all(t<10):
        print t
    else:
        print 'none'

[2 5]
[4 7]
[8 6]
none
none
none
none
none

Answer 4

you can also get list of indexes and checked condition with list comprehension:

>>> T = [[2,5],[4,7],[8,6],[34,74],[32,35],[24,7],[12,5],[0,34]]
>>> upper = 10
>>> lower = 0
>>> result = [(i, all(lower < x < upper for x in l)) for i, l in enumerate(T)]
[(0, True), (1, True), (2, True), (3, False), (4, False), (5, False), (6, False), (7, False)]