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How can I get the second minimum value from each column? I have this array:
A = [[72 76 44 62 81 31]
[54 36 82 71 40 45]
[63 59 84 36 34 51]
[58 53 59 22 77 64]
[35 77 60 76 57 44]]
I wish to have output like:
A = [54 53 59 36 40 44]
359
min to return the minimum value, or equivalently for an array arrname use arrname. min() . As you mentioned, numpy. argmin returns the index of the minimum value (of course, you can then use this index to return the minimum value by indexing your array with it).
You can easily find the index of the max value in a 1-dimensional NumPy array. But for the 2D array, you have to use Numpy module unravel_index. It will easily find the Index of the Max and Min value.
We can find the minimum and maximum values from the each row of a 2D numpy array by using the "min" and "max" functions available in the Numpy library.
Try this, in just one line:
[sorted(i)[1] for i in zip(*A)]
in action:
In [12]: A = [[72, 76, 44, 62, 81, 31],
...: [54 ,36 ,82 ,71 ,40, 45],
...: [63 ,59, 84, 36, 34 ,51],
...: [58, 53, 59, 22, 77 ,64],
...: [35 ,77, 60, 76, 57, 44]]
In [18]: [sorted(i)[1] for i in zip(*A)]
Out[18]: [54, 53, 59, 36, 40, 44]
zip(*A)will transpose your list of list so the columns become rows.
and if you have duplicate value, for example:
In [19]: A = [[72, 76, 44, 62, 81, 31],
...: [54 ,36 ,82 ,71 ,40, 45],
...: [63 ,59, 84, 36, 34 ,51],
...: [35, 53, 59, 22, 77 ,64], # 35
...: [35 ,77, 50, 76, 57, 44],] # 35
If you need to skip both 35s, you can use set():
In [29]: [sorted(list(set(i)))[1] for i in zip(*A)]
Out[29]: [54, 53, 50, 36, 40, 44]
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