Easy way to set the position of x-axis in pandas? - python

I have a chart, created in pandas, where I've set the y-axis to range from -100 to -100.
Is there an easy way to have the x-axis cross the y-axis at y=0, instead of crossing at y=-100
(or, how to display the x-axis at the vertical center, instead of at the bottom of the chart)
Solutions I've seen seem to use subplots or spines, which seem to be overly complicated for my purpose. I am looking for something more integrated with pandas, like passing the ylim or style argument)
Sample code:
from pandas import Series
s=Series([-25,0,70])
s.plot(ylim=(-100,100))

The solution I have so far is indeed using subplots:
from pandas import Series
s=Series([-25,0,70])
import matplotlib.pyplot as plt
fig=plt.figure()
ax=fig.add_subplot(111)
ax.set_ylabel('percentage')
ax.spines['bottom'].set_position('zero') # x-axis where y=0
#ax.spines['bottom'].set_position('center') # x-axis at center (not necessarily y=0)
#ax.spines['bottom'].set_position(('data', 50)) # x-axis where y=50
ax.spines['top'].set_color('none') # hide top axis
ax.spines['right'].set_color('none') # hide right axis
s.plot(ylim=(-100,100))
Not sure why the gridline at the bottom is not shown, but not an issue for me

Related

How to change the positions of subplot titles and axis labels in Seaborn FacetGrid?

I am trying to plot a polar plot using Seaborn's facetGrid, similar to what is detailed on seaborn's gallery
I am using the following code:
sns.set(context='notebook', style='darkgrid', palette='deep', font='sans-serif', font_scale=1.25)
# Set up a grid of axes with a polar projection
g = sns.FacetGrid(df_total, col="Construct", hue="Run", col_wrap=5, subplot_kws=dict(projection='polar'), size=5, sharex=False, sharey=False, despine=False)
# Draw a scatterplot onto each axes in the grid
g.map(plt.plot, 'Rad', ''y axis label', marker=".", ms=3, ls='None').set_titles("{col_name}")
plt.savefig('./image.pdf')
Which with my data gives the following:
I want to keep this organisation of 5 plots per line.
The problem is that the title of each subplot overlap with the values of the ticks, same for the y axis label.
Is there a way to prevent this behaviour? Can I somehow shift the titles slightly above their current position and can I shift the y axis labels slightly on the left of their current position?
Many thanks in advance!
EDIT:
This is not a duplicate of this SO as the problem was that the title of one subplot overlapped with the axis label of another subplot.
Here my problem is that the title of one subplot overlaps with the ticks label of the same subplot and similarly the axis label overlaps with the ticks label of the same subplot.
I also would like to add that I do not care that they overlap on my jupyter notebook (as it as been created with it), however I want the final saved image with no overlap, so perhaps there is something I need to do to save the image in a slightly different format to avoid that, but I don't know what (I am only using plt.savefig to save it).
EDIT 2: If someone would like to reproduce the problem here is a minimal example:
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import seaborn as sns
sns.set()
sns.set(context='notebook', style='darkgrid', palette='deep', font='sans-serif', font_scale=1.5)
# Generate an example radial datast
r = np.linspace(0, 10000, num=100)
df = pd.DataFrame({'label': r, 'slow': r, 'medium-slow': 1 * r, 'medium': 2 * r, 'medium-fast': 3 * r, 'fast': 4 * r})
# Convert the dataframe to long-form or "tidy" format
df = pd.melt(df, id_vars=['label'], var_name='speed', value_name='theta')
# Set up a grid of axes with a polar projection
g = sns.FacetGrid(df, col="speed", hue="speed",
subplot_kws=dict(projection='polar'), size=4.5, col_wrap=5,
sharex=False, sharey=False, despine=False)
# Draw a scatterplot onto each axes in the grid
g.map(plt.scatter, "theta", "label")
plt.savefig('./image.png')
plt.show()
Which gives the following image in which the titles are not as bad as in my original problem (but still some overlap) and the label on the left hand side overlap completely.
In order to move the title a bit higher you can set at new position,
ax.title.set_position([.5, 1.1])
In order to move the ylabel a little further left, you can add some padding
ax.yaxis.labelpad = 25
To do this for the axes of the facetgrid, you'd do:
for ax in g.axes:
ax.title.set_position([.5, 1.1])
ax.yaxis.labelpad = 25
The answer provided by ImportanceOfBeingErnest in this SO question may help.

customize ticks label when sharex is on in matplotlib

I have two stacked subplots which share the x axis, for both subplots visibility of ticks is set to false because I don't want to see tick labels. after having plotted both subplots, I would like to put some extra ticks on x-asis, only for second subplot, but they don't have to became the main ticks.
I mean, doing this:
#xticks = list of x points
#xlabs = list of labels
#secondplot.set_xticks(xticks)
#secondplot.set_xticklabels(xlabs)
will change the first sublplot grid according to these new ticks as if they became the new major ticks. is there a way to label just some x-axis point in second subplot without affecting the whole plots area? thank you
I know im late to the party but I faced a similar problem and want to share my solution, in case anyone else needs help.
You can use matplotlib.axes.Axes.tick_params to control the style of both major and minor ticks of the axes. Setting the tick lengths of the first subplot to 0 should do the trick:
ax.tick_params(axis="x", which="both", length=0.)
axis ("x", "y" or "both") selects the axes, on which the setting has an effect, which ("major", "minor" or "both") chooses the tick type.
Of course you can then also set major and minor ticks with ax.set_xticks(ticks, minor=False). A full example:
import matplotlib.pyplot as plt
fig, axarr = plt.subplots(2, 1, sharex="col")
axarr[0].plot(range(11))
axarr[1].plot(range(11)[::-1])
axarr[0].tick_params(axis="x", which="both", length=0.)
axarr[1].set_xticks(range(0, 11, 3))
axarr[1].set_xticks(range(0, 11), minor=True)
plt.show()
which yields: https://i.stack.imgur.com/oc7y0.png
This works for removing the tick labels from a single axis when using sharex, but I don't see a solution to also remove the ticks..
import matplotlib.pylab as pl
pl.figure()
ax1=pl.subplot(211)
ax1.plot([0,10],[0,10])
ax2=pl.subplot(212, sharex=ax1)
ax2.plot([0,10],[10,0])
pl.setp(ax1.get_xticklabels(), visible=False)

Gridlines that overlap with axes spines have different width from other gridlines

I'm using Seaborn to make some plots using the whitegrid style. After calling despine(), I'm seeing that the gridlines that would overlap with the axes spines have smaller linewidth than the other gridlines. But it seems like this only happens when I save the plots as pdf. I'm sharing
three different figures with different despine configurations that show the effect.
Does anyone know why this occurs? And is there a simple fix?
PDF plot with all spines
PDF plot that despines all axes
PDF plot that despines left, top, and right axes
Code:
splot = sns.boxplot(data=df, palette=color, whis=np.inf, width=0.5, linewidth = 0.5)
splot.set_ylabel('Normalized WS')
plt.xticks(rotation=90)
plt.tight_layout()
sns.despine(left=True, bottom=True)
plt.savefig('test.pdf', bbox_inches='tight')
Essentially what's happening here is that the grid lines are centered on the tick position, so the outer half of the extreme grid lines are not drawn because they extend past the limits of the axes.
One approach is to disable clipping for the grid lines:
import numpy as np
import seaborn as sns
sns.set(style="whitegrid", rc={"grid.linewidth": 5})
x = np.random.randn(100, 6)
ax = sns.boxplot(data=x)
ax.yaxis.grid(True, clip_on=False)
sns.despine(left=True)
My hacking solution now is to not despine the top and bottom axes and make them the same width as the gridlines. This is not ideal. If someone can point out a way to fix the root cause, I will really appreciate that.

matplotlib: ylabels of subplots overlapping

I have three subplots sharing x-axis. I need hspace between subplots to be 0.0, but then y-labels of subplots overlap.
ylabels of subplots overlap
Is there any way to move extreme y-labels of each subplot a little bit downwards or upwards (as I did manually in mspaint, on the right)?
Piotr
There is a dedicated ticker formater class exactly for this purpose.
http://matplotlib.org/api/ticker_api.html#matplotlib.ticker.MaxNLocator
from matplotlib.ticker import MaxNLocator
ax2.yaxis.set_major_locator(MaxNLocator(prune='upper')) #remove highest label so it wont overlapp with stacked plot.
Edit:
Actually this wont move them, just remove the overlapping ticks.

autofmt_xdate deletes x-axis labels of all subplots

I use autofmt_xdate to plot long x-axis labels in a readable way. The problem is, when I want to combine different subplots, the x-axis labeling of the other subplots disappears, which I do not appreciate for the leftmost subplot in the figure below (two rows high). Is there a way to prevent autofmt_xdate from quenching the other x-axis labels? Or is there another way to rotate the labels? As you can see I experimented with xticks and "rotate" as well, but the results were not satisfying because the labels were rotated around their center, which resulted in messy labeling.
Script that produces plot below:
from matplotlib import pyplot as plt
from numpy import arange
import numpy
from matplotlib import rc
rc("figure",figsize=(15,10))
#rc('figure.subplot',bottom=0.1,hspace=0.1)
rc("legend",fontsize=16)
fig = plt.figure()
Test_Data = numpy.random.normal(size=20)
fig = plt.figure()
Dimension = (2,3)
plt.subplot2grid(Dimension, (0,0),rowspan=2)
plt.plot(Test_Data)
plt.subplot2grid(Dimension, (0,1),colspan=2)
for i,j in zip(Test_Data,arange(len(Test_Data))):
plt.bar(i,j)
plt.legend(arange(len(Test_Data)))
plt.subplot2grid(Dimension, (1,1),colspan=2)
xticks = [r"%s (%i)" % (a,b) for a,b in zip(Test_Data,Test_Data)]
plt.xticks(arange(len(Test_Data)),xticks)
fig.autofmt_xdate()
plt.ylabel(r'$Some Latex Formula/Divided by some Latex Formula$',fontsize=14)
plt.plot(Test_Data)
#plt.setp(plt.xticks()[1],rotation=30)
plt.tight_layout()
#plt.show()
This is actually a feature of the autofmt_xdate method. From the documentation of the autofmt_xdate method:
Date ticklabels often overlap, so it is useful to rotate them and right align them. Also, a common use case is a number of subplots with shared xaxes where the x-axis is date data. The ticklabels are often long, and it helps to rotate them on the bottom subplot and turn them off on other subplots, as well as turn off xlabels.
If you want to rotate the xticklabels of the bottom right subplot only, use
plt.setp(plt.xticks()[1], rotation=30, ha='right') # ha is the same as horizontalalignment
This rotates the ticklabels 30 degrees and right aligns them (same result as when using autofmt_xdate) for the bottom right subplot, leaving the two other subplots unchanged.

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