I'm trying to create an array of of the number of elements I have in another array, but appending to the array in a loop gives me too many numbers.
xaxis = np.zeros(len(newdates))
for i in newdates:
xaxis = np.append(xaxis, i)
Instead of [1,2,3,4,.....] like I want, it's giving me an array of [1,1,2,1,2,3,1,2,3,4,.....].
This seems like an easy question, but it's hanging me up for some reason.
You can avoid the loop entirely with something like (assuming len(newdates) is 3):
>>> np.array(range(1, len(newdates)+1))
array([1, 2, 3])
You are appending i values, the values inside newdates, to xaxis list, which is [0]*len(newdates). The code below illustrates this:
>>> import numpy as np
>>> newdates = range(10)
>>> xaxis = np.zeros(len(newdates))
>>> for i in newdates:
... xaxis = np.append(xaxis, i)
...
>>> print xaxis
[ 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 1. 2. 3. 4. 5. 6. 7.
8. 9.]
I'm not sure about what you want to do, but I think it could be easily solved by:
xaxis = range(len(newdates))
While someone gave you a better way to do it I feel you should also see what you're doing wrong
for foo in bar:
loops over all of the elements of bar and calls them foo within the for loop. So if I had
newdates = [10,9,8,7,6,5,4,3,2,1]
and I did your code
xaxis = np.zeros(len(newdates))
for i in newdates:
xaxis = np.append(xaxis, i)
xaxis would be a bunch of 0's the length of newdates and then the numbers in newdates because within the loop i corresponds to an element of newdates
