Matplotlib 2.0 stripes in histogram

Question

I get vertical stripes between the bins when creating a histogram with matplotlib 2.0.2, python2.7, Win7,64bit, visible both in the pdf and png created. I am usig pgf with latex to create a PDF which I will use by includegraphics in a pdflatex document. The PNG created is just a quick check.

This was not the case in Matplotlib 1.5.3. How do I get rid of these white lines separating individual bins?

Things tried:

Switching antialiasing on/off (aa=True/False in hist command)
drawing a line (ls="-"/ls="none" in hist command)
One thing which would kind of work is giving a width to the bins (width=2.3), but this also does not work for a PDF in all zoom values.

Code to produce the image

import matplotlib as mpl
mpl.use('pgf')
pgf_with_latex = {                      # setup matplotlib to use latex for output
    "pgf.texsystem": "pdflatex",        # change this if using xetex or lautex
    "text.usetex": True,                # use LaTeX to write all text
    "font.family": "serif",
    "font.serif": [],                   # blank entries should cause plots to inherit fonts from the document
    "font.sans-serif": [],
    "font.monospace": [],
    "axes.labelsize": 10,               # LaTeX default is 10pt font.
    "font.size": 8,
    "legend.fontsize": 7,               # Make the legend/label fonts a little smaller
    "xtick.labelsize": 7,
    "ytick.labelsize": 7,
    "pgf.preamble": [
        r"\usepackage[utf8x]{inputenc}",    # use utf8 fonts becasue your computer can handle it :)
        r"\usepackage[T1]{fontenc}",        # plots will be generated using this preamble
        r"\usepackage{siunitx}",
        r"\DeclareSIUnit[number-unit-product = {}] ",
        r"\LSB{LSB}",
        ]
    }
mpl.rcParams.update(pgf_with_latex)

import matplotlib.pyplot as pl
import numpy as np

fig=pl.figure(figsize=(3,2))

ax1 = fig.add_subplot(111)
dat=np.random.normal(-120-60,40,200000).astype(int)
bins=np.arange(int(np.amin(dat))-.5,127.5,2)
ax1.hist(dat, bins = bins, stacked = True)
ax1.set_title("\emph{(a)} minimal example")
ax1.set_yscale("log", nonposy="clip")
ax1.set_ylim(0.8, 20000)
ax1.set_xlim(None, 130)
ax1.set_ylabel("frequency")
ax1.set_xlabel("data")
ax1.set_xticks([-300,-200, -127,0,127])
fig.tight_layout(h_pad=1,w_pad=0.2)

pl.savefig('test.png', bbox_inches='tight',dpi=600)
pl.savefig('test.pdf', bbox_inches='tight',dpi=600)

Output of the above code:

Matplotlib 2.0 stripes in histogram

1 Answers