[Matplotlib-users] MultipleLocator and MaxNLocator

Discussion:

Tommy Carstensen

2015-02-14 01:29:02 UTC

Permalink

Is it possible to combine MultipleLocator and MaxNLocator? One seems
to erase the effect of the other.

Eric Firing

2015-02-14 02:01:46 UTC

Permalink

Post by Tommy Carstensen
Is it possible to combine MultipleLocator and MaxNLocator? One seems
to erase the effect of the other.

Tommy Carstensen

2015-02-14 15:47:42 UTC

Permalink

Thanks for you answer Eric. I had to get some sleep before trying out
things. I currently have the code below, but it does not remove the
zero value tick. It removes the tick at 5 and 10 however.

import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.xaxis.set_major_locator(MultipleLocator(5))
xticks = ax1.xaxis.get_major_ticks()
#xticks[0].label1.set_visible(False)
#xticks[-1].label1.set_visible(False)
ax1.set_xticks(ax1.get_xticks()[1:-1])
ax1.plot(list(range(11)))
plt.show()

Post by Eric Firing

Post by Tommy Carstensen
Is it possible to combine MultipleLocator and MaxNLocator? One seems
to erase the effect of the other.

They are for different situations. MultipleLocator is for when you know
what you want your tick interval to be; MaxNLocator is for when you
don't know that, but you do know roughly how many ticks you want, and
what sort of numerical intervals are acceptable.
Eric
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Eric Firing

2015-02-14 17:17:11 UTC

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What is the effect you are trying to achieve? How would you describe
the desired tick placement algorithm?

Eric

Post by Tommy Carstensen
import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.xaxis.set_major_locator(MultipleLocator(5))
xticks = ax1.xaxis.get_major_ticks()
#xticks[0].label1.set_visible(False)
#xticks[-1].label1.set_visible(False)
ax1.set_xticks(ax1.get_xticks()[1:-1])
ax1.plot(list(range(11)))
plt.show()

Post by Eric Firing

Post by Tommy Carstensen
Is it possible to combine MultipleLocator and MaxNLocator? One seems
to erase the effect of the other.

Ryan Nelson

2015-02-14 17:27:32 UTC

Permalink

Tommy, (Sorry for the doubleup. I just realized I forgot to hit reply-all.)

Do you want to remove the tick at 0 and only have 5,10, etc.? Could you
just do something like this instead:

import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.set_xticks(range(5,11,5))
ax1.plot(range(11))
plt.show()

Ryan

On Sat, Feb 14, 2015 at 10:47 AM, Tommy Carstensen <

Post by Tommy Carstensen
Thanks for you answer Eric. I had to get some sleep before trying out
things. I currently have the code below, but it does not remove the
zero value tick. It removes the tick at 5 and 10 however.
import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.xaxis.set_major_locator(MultipleLocator(5))
xticks = ax1.xaxis.get_major_ticks()
#xticks[0].label1.set_visible(False)
#xticks[-1].label1.set_visible(False)
ax1.set_xticks(ax1.get_xticks()[1:-1])
ax1.plot(list(range(11)))
plt.show()

Post by Eric Firing

Post by Tommy Carstensen
Is it possible to combine MultipleLocator and MaxNLocator? One seems
to erase the effect of the other.

------------------------------------------------------------------------------

Post by Eric Firing
Dive into the World of Parallel Programming. The Go Parallel Website,
sponsored by Intel and developed in partnership with Slashdot Media, is

your

Post by Eric Firing
hub for all things parallel software development, from weekly thought
leadership blogs to news, videos, case studies, tutorials and more. Take

Post by Eric Firing
look and join the conversation now. http://goparallel.sourceforge.net/
_______________________________________________
Matplotlib-users mailing list
https://lists.sourceforge.net/lists/listinfo/matplotlib-users

------------------------------------------------------------------------------
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sponsored 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/
_______________________________________________
Matplotlib-users mailing list
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Tommy Carstensen

2015-02-14 17:33:14 UTC

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Eric Firing

2015-02-14 18:19:06 UTC

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Post by Tommy Carstensen
Thanks again Ryan. That's exactly what I want to achieve; i.e. remove
the tick at 0 and only keep 5 and 10. Your solution works, but it's a
bit of hack to use magic constants. I could however get those values
from the xlim.
Eric, I would describe the desired tick placement algorithm as
ax1.xaxis.set_major_locator(MaxNLocator(prune='lower'))

Aha! The problem is that the MaxNLocator is the only one with the prune
kwarg. It could be added to the MultipleLocator. For now, though, you
can make your own specialized Locator, hardwired to omit the first tick,
like this:

from matplotlib.ticker import MultipleLocator

class TrimmedMultipleLocator(MultipleLocator):
def tick_values(self, vmin, vmax):
return MultipleLocator.tick_values(self, vmin, vmax)[1:]

then just use

ax1.xaxis.set_major_locator(TrimmedMultipleLocator(5))

I haven't tested it--but give it a try. What it is doing is making a
subclass of MultipleLocator, and altering only the one little bit of its
behavior that you want to modify. Everything else is automatically
inherited from the base class, MultipleLocator.

Eric

Post by Tommy Carstensen
ax1.xaxis.set_major_locator(MultipleLocator(5))

Post by Ryan Nelson
Tommy, (Sorry for the doubleup. I just realized I forgot to hit reply-all.)
Do you want to remove the tick at 0 and only have 5,10, etc.? Could you just
import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.set_xticks(range(5,11,5))
ax1.plot(range(11))
plt.show()
Ryan
On Sat, Feb 14, 2015 at 10:47 AM, Tommy Carstensen

Post by Eric Firing

Post by Tommy Carstensen
Is it possible to combine MultipleLocator and MaxNLocator? One seems
to erase the effect of the other.

Tommy Carstensen

2015-02-14 18:45:47 UTC

Permalink

Erik, that doesn't seem to work either. I tried this:

import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
class TrimmedMultipleLocator(MultipleLocator):
def tick_values(self, vmin, vmax):
return MultipleLocator.tick_values(self, vmin, vmax)[2:]
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.xaxis.set_major_locator(TrimmedMultipleLocator(5))
#xticks[0].label1.set_visible(False)
#xticks[-1].label1.set_visible(False)
#ax1.set_xticks(ax1.xaxis.get_major_ticks()[1:-1])
ax1.plot(list(range(21)))
plt.show()

Here is an example of the use of prune='lower', but it does not allow
one to set the tick step size:
http://stackoverflow.com/questions/9422587/overlapping-y-axis-tick-label-and-x-axis-tick-label-in-matplotlib

I think my best bet is to just set those ticks manually.

Post by Eric Firing

Aha! The problem is that the MaxNLocator is the only one with the prune
kwarg. It could be added to the MultipleLocator. For now, though, you
can make your own specialized Locator, hardwired to omit the first tick,
from matplotlib.ticker import MultipleLocator
return MultipleLocator.tick_values(self, vmin, vmax)[1:]
then just use
ax1.xaxis.set_major_locator(TrimmedMultipleLocator(5))
I haven't tested it--but give it a try. What it is doing is making a
subclass of MultipleLocator, and altering only the one little bit of its
behavior that you want to modify. Everything else is automatically
inherited from the base class, MultipleLocator.
Eric

Post by Tommy Carstensen
ax1.xaxis.set_major_locator(MultipleLocator(5))

Post by Eric Firing

Post by Tommy Carstensen
Is it possible to combine MultipleLocator and MaxNLocator? One seems
to erase the effect of the other.

Ryan Nelson

2015-02-14 19:01:45 UTC

Permalink

Tommy,

I'm sorry. I forgot to hit send all *again*. Below is my original message,
but the function I wrote is updated because it wasn't exactly correct....

Ah. I was working on something to help out, so I'm just seeing Eric's very
elegant solution, which I have yet to try. However, I feel like you might
run into some problems if you always drop the first tick. For example, try
this plot:
______________
import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
import numpy as np
xs = np.linspace(2,12,1000)
ys = np.sin(xs)
n = 5
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.plot(xs, ys)
ax1.xaxis.set_major_locator(MultipleLocator(5))
plt.show()
_____________
In this case, dropping the first tick will result in only one tick on the
screen.

What is your use-case? Are you annoyed that the axis labels are overlapping
at the far left? If that's the case, here's a little function (trimticks)
that I whipped up that might help. It drops the far left or far right label
if it is exactly at the edge of the axes. Should work for y axes as well.
_____________
def trimticks(ax, n=5):
xmin, xmax = ax.get_xlim()
if xmin%n == 0:
xmin = xmin+n
else:
xmin = xmin + n - xmin%n

if not xmax%n == 0:
xmax = xmax + n - xmax%n

ticks = np.arange(xmin, xmax, n)
ax.set_xticks(ticks)

import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
import numpy as np
xs = np.linspace(0,20,10000)
ys = np.sin(xs)
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.plot(xs, ys)
trimticks(ax1)
plt.show()

___________________

On Sat, Feb 14, 2015 at 1:45 PM, Tommy Carstensen <

Post by Tommy Carstensen
import matplotlib.pyplot as plt
from matplotlib.ticker import MultipleLocator
return MultipleLocator.tick_values(self, vmin, vmax)[2:]
fig = plt.figure()
ax1 = fig.add_subplot(111)
ax1.xaxis.set_major_locator(TrimmedMultipleLocator(5))
#xticks[0].label1.set_visible(False)
#xticks[-1].label1.set_visible(False)
#ax1.set_xticks(ax1.xaxis.get_major_ticks()[1:-1])
ax1.plot(list(range(21)))
plt.show()
Here is an example of the use of prune='lower', but it does not allow
http://stackoverflow.com/questions/9422587/overlapping-y-axis-tick-label-and-x-axis-tick-label-in-matplotlib
I think my best bet is to just set those ticks manually.

Post by Eric Firing

Aha! The problem is that the MaxNLocator is the only one with the prune
kwarg. It could be added to the MultipleLocator. For now, though, you
can make your own specialized Locator, hardwired to omit the first tick,
from matplotlib.ticker import MultipleLocator
return MultipleLocator.tick_values(self, vmin, vmax)[1:]
then just use
ax1.xaxis.set_major_locator(TrimmedMultipleLocator(5))
I haven't tested it--but give it a try. What it is doing is making a
subclass of MultipleLocator, and altering only the one little bit of its
behavior that you want to modify. Everything else is automatically
inherited from the base class, MultipleLocator.
Eric

Post by Tommy Carstensen
ax1.xaxis.set_major_locator(MultipleLocator(5))

Post by Ryan Nelson
Tommy, (Sorry for the doubleup. I just realized I forgot to hit

reply-all.)