This may be a silly question, but I've just started using numpy and I have to figure out how to perform some simple operations.
Suppose that I have the 2x3 array
array([[1, 3, 5],
[2, 4, 6]])
And that I want to perform some operation on the first column, for example subtract 1 to all the elements to get
array([[0, 3, 5],
[1, 4, 6]])
How can I perform such an operation?
arr
# array([[1, 3, 5],
# [2, 4, 6]])
arr[:,0] = arr[:,0] - 1 # choose the first column here, subtract one and
# assign it back to the same column
arr
# array([[0, 3, 5],
# [1, 4, 6]])
np.mean(dat[:,5]) after using genfromtxt to read a csv file into a numpy array. You wouldn't think that was so far off the beaten path. But you nailed it for me. Thank you very muchcsv.read() so I can preserve my index values which are a date and a time and show up as nan in genfromtxt, now that I know how this works. This is a great solution. Thank goodness for Google leading me here. And thank you for this answer being here to find. I have to laugh, seeing all the related Q's that Google could have found first. It works in mysterious ways.