TypeError: only length-1 arrays can be converted to Python scalars while trying to exponentially fit data

user3291404 picture user3291404 · Feb 10, 2014 · Viewed 310.4k times · Source
f=np.loadtxt('Single Small Angle 1.txt',unpack=True,skiprows=2)
g=np.loadtxt('Single Small Angle 5.txt',unpack=True,skiprows=2)

x = f-g[:,:11944]
t=range(len(x))
m=math.log10(abs(x))

np.polyfit(t,m)

plt.plot(t,abs(x))
plt.show()

I'm just not sure on how to fix my issue. It keeps saying:

m=math.log10(abs(x))
TypeError: only length-1 arrays can be converted to Python scalars

Answer

Tom Pohl picture Tom Pohl · Feb 11, 2014

Non-numpy functions like math.abs() or math.log10() don't play nicely with numpy arrays. Just replace the line raising an error with:

m = np.log10(np.abs(x))

Apart from that the np.polyfit() call will not work because it is missing a parameter (and you are not assigning the result for further use anyway).