How to add a second scale to a heatmap? - python

This way I created my heatmap:
fig = plt.figure(figsize = (8.27, 13.69), dpi = 100)
fig, ax = plt.subplots(1,1,figsize = (8.27, 13.69))
fig = plt.gcf()
heatplot = ax.imshow(c, cmap='rainbow', aspect='auto',\
norm=MidpointNormalize(midpoint=0.90))
c is the array with the heatmap values, normalised to one.
With ax.set_xticklabels(), ax.set_xticks(), ax.set_yticklabels() and ax.set_yticks(), I've added the axis to its heatmap. Now I would like to add a second y-axis. The orientation of the colorbar is horizontal.
EDIT:
With the Help of Bazingaa i´ve got a second y-axis, but there is an offset:
ax1.set_yticks(np.arange(len(TITLES)), minor=False) centers the ticks.

To add a second y axis, you have to use:
ax2 = ax1.twinx()
where ax1 is the current/first axis. In your case ax1 is ax. Then if you plot data using ax2, the y-values will be displayed on the right hand side y axis. More info here

Solved the EDITED PART of my question this way:
ax2.set_ylim(ax1.get_ylim()) <-- This solvs the "Offset" between both scales
ax2.set_yticks(np.arange(len(ELEMENT[1])), minor=False)
ax2.set_yticklabels(ELEMENT[1])
Where did i find it?: How do I align gridlines for two y-axis scales using Matplotlib?
Answered by: Hugo Alain Oliva

I decided that using subplots was less confusion and put two heat maps side by side

Related

Adding secondary y labels to heatmap in matplotlib [duplicate]

I'm trying to plot a two-dimensional array in matplotlib using imshow(), and overlay it with a scatterplot on a second y axis.
oneDim = np.array([0.5,1,2.5,3.7])
twoDim = np.random.rand(8,4)
plt.figure()
ax1 = plt.gca()
ax1.imshow(twoDim, cmap='Purples', interpolation='nearest')
ax1.set_xticks(np.arange(0,twoDim.shape[1],1))
ax1.set_yticks(np.arange(0,twoDim.shape[0],1))
ax1.set_yticklabels(np.arange(0,twoDim.shape[0],1))
ax1.grid()
#This is the line that causes problems
ax2 = ax1.twinx()
#That's not really part of the problem (it seems)
oneDimX = oneDim.shape[0]
oneDimY = 4
ax2.plot(np.arange(0,oneDimX,1),oneDim)
ax2.set_yticks(np.arange(0,oneDimY+1,1))
ax2.set_yticklabels(np.arange(0,oneDimY+1,1))
If I only run everything up to the last line, I get my array fully visualised:
However, if I add a second y axis (ax2=ax1.twinx()) as preparation for the scatterplot, it changes to this incomplete rendering:
What's the problem? I've left a few lines in the code above describing the addition of the scatterplot, although it doesn't seem to be part of the issue.
Following the GitHub discussion which Thomas Kuehn has pointed at, the issue has been fixed few days ago. In the absence of a readily available built, here's a fix using the aspect='auto' property. In order to get nice regular boxes, I adjusted the figure x/y using the array dimensions. The axis autoscale feature has been used to remove some additional white border.
oneDim = np.array([0.5,1,2.5,3.7])
twoDim = np.random.rand(8,4)
plt.figure(figsize=(twoDim.shape[1]/2,twoDim.shape[0]/2))
ax1 = plt.gca()
ax1.imshow(twoDim, cmap='Purples', interpolation='nearest', aspect='auto')
ax1.set_xticks(np.arange(0,twoDim.shape[1],1))
ax1.set_yticks(np.arange(0,twoDim.shape[0],1))
ax1.set_yticklabels(np.arange(0,twoDim.shape[0],1))
ax1.grid()
ax2 = ax1.twinx()
#Required to remove some white border
ax1.autoscale(False)
ax2.autoscale(False)
Result:

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.

How to get rid of extra white space on subplots with shared axes?

I'm creating a plot using python 3.5.1 and matplotlib 1.5.1 that has two subplots (side by side) with a shared Y axis. A sample output image is shown below:
Notice the extra white space at the top and bottom of each set of axes. Try as I might I can't seem to get rid of it. The overall goal of the figure is to have a waterfall type plot on the left with a shared Y axes with the plot on the right.
Here's some sample code to reproduce the image above.
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
%matplotlib inline
# create some X values
periods = np.linspace(1/1440, 1, 1000)
# create some Y values (will be datetimes, not necessarily evenly spaced
# like they are in this example)
day_ints = np.linspace(1, 100, 100)
days = pd.to_timedelta(day_ints, 'D') + pd.to_datetime('2016-01-01')
# create some fake data for the number of points
points = np.random.random(len(day_ints))
# create some fake data for the color mesh
Sxx = np.random.random((len(days), len(periods)))
# Create the plots
fig = plt.figure(figsize=(8, 6))
# create first plot
ax1 = plt.subplot2grid((1,5), (0,0), colspan=4)
im = ax1.pcolormesh(periods, days, Sxx, cmap='viridis', vmin=0, vmax=1)
ax1.invert_yaxis()
ax1.autoscale(enable=True, axis='Y', tight=True)
# create second plot and use the same y axis as the first one
ax2 = plt.subplot2grid((1,5), (0,4), sharey=ax1)
ax2.scatter(points, days)
ax2.autoscale(enable=True, axis='Y', tight=True)
# Hide the Y axis scale on the second plot
plt.setp(ax2.get_yticklabels(), visible=False)
#ax1.set_adjustable('box-forced')
#ax2.set_adjustable('box-forced')
fig.colorbar(im, ax=ax1)
As you can see in the commented out code I've tried a number of approaches, as suggested by posts like https://github.com/matplotlib/matplotlib/issues/1789/ and Matplotlib: set axis tight only to x or y axis.
As soon as I remove the sharey=ax1 part of the second subplot2grid call the problem goes away, but then I also don't have a common Y axis.
Autoscale tends to add a buffer to the data so that all of the data points are easily visible and not part-way cut off by the axes.
Change:
ax1.autoscale(enable=True, axis='Y', tight=True)
to:
ax1.set_ylim(days.min(),days.max())
and
ax2.autoscale(enable=True, axis='Y', tight=True)
to:
ax2.set_ylim(days.min(),days.max())
To get:

Matplotlib: data being plotted over legend when using twinx

I'm trying to use Python and Matplotlib to plot a number of different data sets. I'm using twinx to have one data set plotted on the primary axis and another on the secondary axis. I would like to have two separate legends for these data sets.
In my current solution, the data from the secondary axis is being plotted over the top of the legend for the primary axis, while data from the primary axis is not being plotted over the secondary axis legend.
I have generated a simplified version based on the example here: http://matplotlib.org/users/legend_guide.html
Here is what I have so far:
import matplotlib.pyplot as plt
import pylab
fig, ax1 = plt.subplots()
fig.set_size_inches(18/1.5, 10/1.5)
ax2 = ax1.twinx()
ax1.plot([1,2,3], label="Line 1", linestyle='--')
ax2.plot([3,2,1], label="Line 2", linewidth=4)
ax1.legend(loc=2, borderaxespad=1.)
ax2.legend(loc=1, borderaxespad=1.)
pylab.savefig('test.png',bbox_inches='tight', dpi=300, facecolor='w', edgecolor='k')
With the result being the following plot:
As shown in the plot, the data from ax2 is being plotted over the ax1 legend and I would like the legend to be over the top of the data. What am I missing here?
Thanks for the help.
You could replace your legend setting lines with these:
ax1.legend(loc=1, borderaxespad=1.).set_zorder(2)
ax2.legend(loc=2, borderaxespad=1.).set_zorder(2)
And it should do the trick.
Note that locations have changed to correspond to the lines and there is .set_zorder() method applied after the legend is defined.
The higher integer in zorder the 'higher' layer it will be painted on.
The trick is to draw your first legend, remove it, and then redraw it on the second axis with add_artist():
legend_1 = ax1.legend(loc=2, borderaxespad=1.)
legend_1.remove()
ax2.legend(loc=1, borderaxespad=1.)
ax2.add_artist(legend_1)
Tribute to #ImportanceOfBeingErnest :
https://github.com/matplotlib/matplotlib/issues/3706#issuecomment-378407795

matplotlib scatter plot change distance in x-axis

I want to plot some Data with Matplotlib scatter plot.
I used the following code to plot the Data as a scatter with using the same axes for the different subplots.
import numpy as np
import matplotlib.pyplot as plt
epsilon= np.array([1,2,3,4,5])
f, (ax1, ax2, ax3, ax4) = plt.subplots(4, sharex= True, sharey=True)
ax1.scatter(epsilon, mean_percent_100_0, color='r', label='Totaldehnung= 0.000')
ax1.scatter(epsilon, mean_percent_100_03, color='g',label='Totaldehnung= 0.003')
ax1.scatter(epsilon, mean_percent_100_05, color='b',label='Totaldehnung= 0.005')
ax1.set_title('TOR_R')
ax2.scatter(epsilon, mean_percent_111_0,color='r')
ax2.scatter(epsilon, mean_percent_111_03,color='g')
ax2.scatter(epsilon, mean_percent_111_05,color='b')
ax3.scatter(epsilon, mean_percent_110_0,color='r')
ax3.scatter(epsilon, mean_percent_110_03,color='g')
ax3.scatter(epsilon, mean_percent_110_05,color='b')
ax4.scatter(epsilon, mean_percent_234_0,color='r')
ax4.scatter(epsilon, mean_percent_234_03,color='g')
ax4.scatter(epsilon, mean_percent_234_05,color='b')
# Fine-tune figure; make subplots close to each other and hide x ticks for
# all but bottom plot.
f.subplots_adjust(hspace=0.13)
plt.setp([a.get_xticklabels() for a in f.axes[:-1]], visible=False)
plt.locator_params(axis = 'y', nbins = 4)
ax1.grid()
ax2.grid()
ax3.grid()
ax4.grid()
plt.show()
Now i want to have a x-axis with smaller space between each point. I tried to change the range but it was not working. Can someone help me?
To make the x ticks come closer you might have to set the dimensions of the figure.
Since, in your case, the figure is already created, Set the size of the plot using set_size_inches method of the figure object.
This question contains a few other ways to do the same.
Adding the following line before the plt.show()
fig.set_size_inches(2,8)
Gives me this :
Which I hope is what you are trying to do.

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