python - variance vs coefficient of variation -

i need identify statistic let me find on digital image line has highest variation. using variance (square units, calculated numpy.var(x)) , coefficient of variation (unitless, calculated numpy.sd(x)/numpy.mean(x)), got different values, here:

v1 = line(var(x))

v2 = line(cv(x))

print(v1,v2)

(12,17)

should not both find same line? 1 better use in case?

coefficient of variation , variance not supposed choose same array on random data. coefficient of variation sensitive both variance , scale of data, whereas variance geared towards variation in data.

please see example:

import numpy np  x = np.random.randn(10) x1= x+10 np.var(x), np.std(x)/np.mean(x)  (2.0571740850649021, -2.2697110381499224)  np.var(x1), np.std(x1)/np.mean(x1)  (2.0571740850649016, 0.1531035017615747) 

which 1 choose depends on application, i'm leaning towards variance in case.