How to convert a list of strings into a numeric numpy array?

Question

I want to be able to calculate the mean, min and max of A:

 import numpy as np

 A = ['33.33', '33.33', '33.33', '33.37']

 NA = np.asarray(A)

 AVG = np.mean(NA, axis=0)

 print AVG

This does not work, unless converted to:

A = [33.33, 33.33, 33.33, 33.37]

Is it possible to perform this conversion automatically?

Answer 1

you want astype

NA = NA.astype(float)

Answer 2

You had a list of strings

You created an array of strings

You needed an array of floats for post processing; so when you create your array specify data type and it will convert strings to floats upon creation

import numpy as np

#list of strings
A = ['33.33', '33.33', '33.33', '33.37']
print A

#numpy of strings
arr = np.array(A)
print arr

#numpy of float32's
arr = np.array(A, dtype=np.float32)
print arr

#post process
print np.mean(arr), np.max(arr), np.min(arr)

>>>
['33.33', '33.33', '33.33', '33.37']
['33.33' '33.33' '33.33' '33.37']
[ 33.33000183  33.33000183  33.33000183  33.36999893]
33.34 33.37 33.33

https://docs.scipy.org/doc/numpy/user/basics.types.html