[Bug] Bar plot with log scale on y axes

Alvaro_Justen_Turica · January 24, 2012, 1:57am

Hello,
I'm using version 1.0.1 and I think this code snippet and the images
attached are enough to explain the bug:

gist.github.com

https://gist.github.com/turicas/1667300

matplotlib-bug-bar-log.py

#!/usr/bin/env python
# coding: utf-8

from numpy import arange
from matplotlib.pyplot import figure


f = figure()
s = f.add_subplot(1, 1, 1)
x = arange(0, 20)

This file has been truncated. show original

Images 'bar-log-bug.png' and 'bar-log-ok.png' must be the same since
it is the same data and same configuration - the bug occurs when we
call set_yscale after calling subplot.bar().

If you confirm the bug, I'll create an issue on GitHub.

Thanks,

···

--
Álvaro Justen "Turicas"
http://blog.justen.eng.br x.com
http://CursoDeArduino.com.br turicas (Álvaro Justen) · GitHub
+55 21 9898-0141

Benjamin_Root · January 24, 2012, 2:54am

This is a known issue and is not a bug. If you know that you are using log scale for your bar graph, then it is best to simply specify it in the bar() command (log=True, I think). Having bar() work when you call set_yscale() before bar() is merely a convenience. Recommended usage is to tell bar() that you are using log scale so that it can avoid taking the log of zero (or negative).

Cheers,
Ben Root

···

On Monday, January 23, 2012, Álvaro Justen [Turicas] <alvarojusten@…287…> wrote:

Hello,
I’m using version 1.0.1 and I think this code snippet and the images

attached are enough to explain the bug:
https://gist.github.com/1667300

Images ‘bar-log-bug.png’ and ‘bar-log-ok.png’ must be the same since

it is the same data and same configuration - the bug occurs when we
call set_yscale after calling subplot.bar().

If you confirm the bug, I’ll create an issue on GitHub.