Extracting rows based on condition on one column

[RockRoll]

Hi Everyone,

Here is an interesting problem I am trying to solve.

I have a (Nx4) array and want to extract those rows which have their third column's element in certain range. Are there existing capabilities in NumPy? Below is a simple example.

PS: I know how for loops can be used by comparing each element of col. 3; and saving the rows that meet the condition. But I want to use NumPy here (like slicing etc., that is promisingly fast). In reality, the arrays I use are large and implementing additional loops will sacrifice comp. times.

For example,:

input = [[1,2,-97,4],
         [5,6,93,8],
         [9,10,-105,12],
         [11,12,105,14]]
 
output = [[1,2,-97,4], # desired output: rows in which column third's element is greater than -100 and less than 100
          [5,6,93,8]]

[Banfa]

Use a filter

computed = list(filter(lambda x: math.fabs(x[2]) < 100, input))