stem plot with horizontal offset (BaseValue)

Community matplotlib-users
#1

Hello,

I found this stem plot example:
http://matplotlib.org/examples/pylab_examples/stem_plot.html

I would like to add an horizontal offset to the step plot. (Ex: +2 on Y
axis)
What is the equivalent of the Matlab "BaseValue" offset in matplotlib.

See Reference:
http://www.mathworks.com/help/matlab/ref/stemseries-properties.html
http://stackoverflow.com/questions/21913995/vertically-offset-stem-plot

Thanks,
ssinfod

···

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#2

I’m not going to claim this is the final answer, but in the documentation for the stem function[1], it specifically says that the horizontal line is drawn at 0.

A workaround is to subtract the offset from your data, and relabel the axes….

[1]http://matplotlib.org/api/pyplot_api.html?highlight=stem#matplotlib.pyplot.stem

···

On Mar 31, 2015, at 11:31AM, ssinfod <ssinfod@...287...> wrote:

Hello,

I found this stem plot example:
http://matplotlib.org/examples/pylab_examples/stem_plot.html

I would like to add an horizontal offset to the step plot. (Ex: +2 on Y
axis)
What is the equivalent of the Matlab "BaseValue" offset in matplotlib.

See Reference:
http://www.mathworks.com/help/matlab/ref/stemseries-properties.html
http://stackoverflow.com/questions/21913995/vertically-offset-stem-plot

Thanks,
ssinfod

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#3

Looking at the source code indicates there is a ‘bottom’ keyword which looks like it controls this, see https://github.com/matplotlib/matplotlib/blob/v1.4.3/lib/matplotlib/axes/_axes.py#L2295

···

On 31 March 2015 at 19:31, ssinfod <ssinfod@…287…> wrote:

Hello,

I found this stem plot example:

http://matplotlib.org/examples/pylab_examples/stem_plot.html

I would like to add an horizontal offset to the step plot. (Ex: +2 on Y

axis)

What is the equivalent of the Matlab “BaseValue” offset in matplotlib.

See Reference:

http://www.mathworks.com/help/matlab/ref/stemseries-properties.html

http://stackoverflow.com/questions/21913995/vertically-offset-stem-plot

Thanks,

ssinfod

–

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by Intel and developed in partnership with Slashdot Media, is your hub for all

things parallel software development, from weekly thought leadership blogs to

news, videos, case studies, tutorials and more. Take a look and join the

conversation now. http://goparallel.sourceforge.net/

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#4

In fact, I would like to draw other stem plots each at different offset.

Ex:

···

-+----_-----_--+-----_---

-+----_---+-_--+--_-----

-+--+-----_------+-----_-

I also found vlines but I have the same problem I don't know how to add a
horizontal offset to the values.
Ex:
import numpy
from matplotlib import pyplot
x = numpy.arange(10)
y = numpy.random.random(10)-0.5
pyplot.vlines(x, 0, y, color='red', bottom=2) # Stems
pyplot.plot(x, y, 'D') # Stem ends
pyplot.plot([x.min(), x.max()], [0, 0], '--') # Middle bar
pyplot.grid(True)
pyplot.show()

ssinfod

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#5

It seems the 'bottom' parameter is the best for me.

Here is the code:
from pylab import *

x = linspace(0.1, 2*pi, 10)
markerline, stemlines, baseline = stem(x, cos(x), '-.', bottom=.5)
setp(markerline, 'markerfacecolor', 'b')
setp(baseline, 'color','r', 'linewidth', 2)

show()

Thanks for your inputs.
ssinfod

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