Sklearn's MinMaxScaler only returns zeros

I had the same problem when I tried scaling with MinMaxScaler from sklearn.preprocessing. Scaler returned me zeros when I used a shape a numpy array as list, i.e. [1, n] which looks like the following:

data = [[44.645, 44.055, 44.54, 44.04, 43.975, 43.49, 42.04, 42.6, 42.46, 41.405]]

I changed the shape of array to [n, 1]. In your case it would like the following

data = [[44.645], 
        [44.055], 
        [44.540], 
        [44.040], 
        [43.975], 
        [43.490], 
        [42.040], 
        [42.600], 
        [42.460], 
        [41.405]]

Then MinMaxScaler worked in proper way.

This is because data is a int32 or int64 and the MinMaxScaler needs a float. Try this:

import numpy as np
data = [44.645, 44.055, 44.54, 44.04, 43.975, 43.49, 42.04, 42.6, 42.46, 41.405]
min_max_scaler = preprocessing.MinMaxScaler(feature_range=(0, 1))
data_scaled = min_max_scaler.fit_transform([np.float32(data)])
print data_scaled