Comparing 2-dimensional numpy array in python

Question

I want to comparing 2 values in a 2-dimensional numpy array. The array is as follows:

a = [[1, 3, 5],
     [4, 8, 1]]

I want to comparing [1, 3, 5] with [4, 8, 1] with a greater value into 1 group. The result I want is like this:

a1 = [4, 8, 5]
a2 = [1, 3, 1]

How could the code be written in python?

Please be clear with your example. What you have shown is not an array and has nothing to do with Numpy, yet you have tagged the question numpy. — Karl Knechtel
– Karl Knechtel, Commented May 1, 2021 at 15:36

sacuL · Accepted Answer · 2021-05-01 15:12:25Z

1

You can use np.sort on axis 0 (column-wise). Reverse the order using [::-1] to get them in descending order

>>> np.sort(a, axis = 0)[::-1]

array([[4, 8, 5],
       [1, 3, 1]])

answered May 1, 2021 at 15:12

sacuL

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Comments

Kevin · Accepted Answer · 2021-05-01 15:26:51Z

0

Since you only have 2 rows you can do this:

a = np.array([[1, 3, 5],
              [4, 8, 1]])

idx = np.greater(*a)

a1 = a[idx.astype(int),np.arange(3)]
a2 = a[~idx.astype(int),np.arange(3)]

answered May 1, 2021 at 15:26

Kevin

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