Changing Values in a List

[DaveG]

I would like to replace all the values (1.3million) in column 3 with 0.00000000. Can someone please advise how I insert this in my code please?

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file = 'Z_Before_After.txt' data = np.genfromtxt(file) xx = data[:, 0] yy = data[:, 1] elevation = data[:, 2] initial = data[; 2]   with open(file, "w") as output:     output.write(xx, yy, initial, elevation)

3560181.703 -3384947.321 -5.02245
3560191.703 -3384947.321 -4.88665
3560201.703 -3384947.321 -4.76042
3560211.703 -3384947.321 -4.66599
3560221.703 -3384947.321 -4.60876
3560231.703 -3384947.321 -4.55424
3560241.703 -3384947.321 -4.49973
3560251.703 -3384947.321 -4.35269
3560261.703 -3384947.321 -4.11991

[jefsummers]

Try like

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import numpy as np data = np.array([[1,2,3],[4,5,6],[7,8,9]]) data[:, 2] = np.zeros(3) data

Output:
array([[1, 2, 0],
       [4, 5, 0],
       [7, 8, 0]])