How to remove gaps between bars in Matplotlib bar chart

Question

I'm making a bar chart in Matplotlib with a call like this:

xs.bar(bar_lefts, bar_heights, facecolor='black', edgecolor='black')

I get a barchart that looks like this:

What I'd like is one with no white gap between consecutive bars, eg more like this:

Is there a way to achieve this in Matplotlib using the bar() function?

Answer 1

Add width=1.0 as a keyword argument to bar() . Eg

xs.bar(bar_lefts, bar_heights, width=1.0, facecolor='black', edgecolor='black') .

This will fill the bars gaps vertically.

Answer 2

Just set the width 1 over the number of bars, so:

width = 1 / len(bar_lefts)
xs.bar(bar_lefts, bar_heights, width=width, color='black')

Answer 3

It has been 8 years since this question was asked, and the matplotlib API now has built-in ways to produce filled, gapless bars: pyplot.step() and pyplot.stairs() with the argument fill=True .

See the docs for a fuller comparison, but the primary difference is that step() defines the step positions with N x and N y values just like plot() would, while stairs() defines the step positions with N heights and N+1 edges, like what hist() returns. It is a subtle difference, and I think both tools can create the same outputs.

Answer 4

You can set the width equal to the distance between two bars:

width = bar_lefts[-1] - bar_lefts[-2]
xs.bar(bar_lefts, bar_heights, width=width)