Mathematical Operations on Array

Terry Reedy tjreedy at
Fri Apr 1 15:45:24 EDT 2011

On 4/1/2011 8:56 AM, Fodness, Bryan C - GS wrote:
> I am loading text into an array and would like to convert the values.
> from math import *
> from numpy import *
> from pylab import *
> data=loadtxt('raw.dat')
> mincos=degrees(acos(data[:,0]))
> minazi=degrees(data[:,1])
> minthick=data[:,2]/0.006858
> I am not sure why degrees() works, but acos() does not.

It is not clear how you know that.

> I receive the following
> Traceback (most recent call last):
> File "C:\", line 6, in ?
> mincos=degrees(acos(float(data[:,0])))
> TypeError: only length-1 arrays can be converted to Python scalars

This does not say where in the expression the problem arose. to be sure

a = float(data([:,0])
b = acod(a)
c = degrees(b)

> Can anyone tell me what I am doing wrong?

Numpy questions get better answers on the numpy list where numpy experts 
hang out.

Terry Jan Reedy

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