If you don’t specify what bins to use,
np.histogramand
pyplot.histwill
use a default setting, which is to use 10 equal bins. The left border of the
1st bin is the smallest value and the right border of the last bin is the
largest.
This is why the bin borders are floating point numbers. You can use the
bins
keyword arguments to enforce another choice of bins, e.g.:
plt.hist(data, bins=np.arange(data.min(), data.max()+1))
Edit: the easiest way to shift all bins to the left is probably just to
subtract 0.5 from all bin borders:
plt.hist(data, bins=np.arange(data.min(), data.max()+1)-0.5)
Another way to achieve the same effect (not equivalent if non-integers are
present):
plt.hist(data, bins=np.arange(data.min(), data.max()+1), align='left')
