How to remove lists from a list

Question

I have created a list where within it I seek to eliminate only the lists whose first value is greater than the second value of it.

I tried creating a second list with the elements to remove but I think it is not the most optimal way.

#y = [] x = [[1, 4], [1, 6], [2, 5], [2, 7], [4, 8], [6, 5], [6, 7], [2, 6], [3, 7], [5, 8], [6, 4], [7, 5]] for i in range(len(x)): if x[i][0] > x[i][1]: print(x[i]) # y.append(x[i])

Is there an optimal way to achieve this?

I want that when printing on screen you get the following:

[[1, 4], [1, 6], [2, 5], [2, 7], [4, 8], [6, 7], [2, 6], [3, 7], [ 5, 8]]

Best regards,

lenik · Accepted Answer · 2020-05-07 01:10:05Z

This should work:

y = [[a,b] for a,b in x if a <= b]

Testing:

>>> x = [[1, 4], [1, 6], [2, 5], [2, 7], [4, 8], [6, 5], [6, 7], [2, 6], [3, 7], [5, 8], [6, 4], [7, 5]] >>> y = [[a,b] for a,b in x if a < b] >>> y [[1, 4], [1, 6], [2, 5], [2, 7], [4, 8], [6, 7], [2, 6], [3, 7], [5, 8]] >>>

@JoshuaHall maybe, OP did not say anything about that, but you're right, I made the change =)

Nick Broderick · Accepted Answer · 2020-05-07 01:11:24Z

This modifies the original list:

for i, (a, b) in enumerate(x): if a > b: del x[i]

jolvi · Accepted Answer · 2020-05-07 01:22:44Z

Creating a new list:

[v for v in x if v[0] <= v[1]]

Or elimination in place:

for i in range(len(x) - 1, -1, -1): # need to start at the end if x[i][0] > x[i][1]: x.pop(i)

hipeople321 · Accepted Answer · 2020-05-07 01:28:44Z

>>> filtered = list(filter(lambda f: f[0] < f[1], x)) >>> print(filtered)

This will create a new list with the desired values, using the built in filter(function, iterable) function.

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