pandas 0.21.0 Timestamp compatibility issue with matplotlib

There is an issue with pandas datetimes and matplotlib coming from the recent release of pandas 0.21, which does not register its converters any more at import. Once you use those converters once (within pandas) they’ll be registered and automatically used by matplotlib as well. A workaround would be to register them manually, import pandas.plotting._converter … Read more

Contour/imshow plot for irregular X Y Z data

Does plt.tricontourf(x,y,z) satisfy your requirements? It will plot filled contours for irregularly spaced data (non-rectilinear grid). You might also want to look into plt.tripcolor(). import numpy as np import matplotlib.pyplot as plt x = np.random.rand(100) y = np.random.rand(100) z = np.sin(x)+np.cos(y) f, ax = plt.subplots(1,2, sharex=True, sharey=True) ax[0].tripcolor(x,y,z) ax[1].tricontourf(x,y,z, 20) # choose 20 contour levels, … Read more

Changing plot scale by a factor in matplotlib

As you have noticed, xscale and yscale does not support a simple linear re-scaling (unfortunately). As an alternative to Hooked’s answer, instead of messing with the data, you can trick the labels like so: ticks = ticker.FuncFormatter(lambda x, pos: ‘{0:g}’.format(x*scale)) ax.xaxis.set_major_formatter(ticks) A complete example showing both x and y scaling: import numpy as np import … Read more

Colouring plot by factor in R

data<-iris plot(data$Sepal.Length, data$Sepal.Width, col=data$Species) legend(7,4.3,unique(data$Species),col=1:length(data$Species),pch=1) should do it for you. But I prefer ggplot2 and would suggest that for better graphics in R.

How to export plots from matplotlib with transparent background?

Use the matplotlib savefig function with the keyword argument transparent=True to save the image as a png file. In [30]: x = np.linspace(0,6,31) In [31]: y = np.exp(-0.5*x) * np.sin(x) In [32]: plot(x, y, ‘bo-‘) Out[32]: [<matplotlib.lines.Line2D at 0x3f29750>] In [33]: savefig(‘demo.png’, transparent=True) Result: Of course, that plot doesn’t demonstrate the transparency. Here’s a screenshot … Read more

draw polar graph in java

You might like to look at Lissajous curves; an example of a = 5, b = 4 (5:4) is shown below. Addendum: Once you see how to plot points in xy coordinates, then you should look at converting between polar and Cartesian coordinates. public class LissajousPanel extends JPanel { private static final int SIZE = … Read more

How to remove or hide y-axis ticklabels from a matplotlib / seaborn plot

seaborn is used to draw the plot, but it’s just a high-level API for matplotlib. The functions called to remove the y-axis labels and ticks are matplotlib methods. After creating the plot, use .set(). .set(yticklabels=[]) should remove tick labels. This doesn’t work if you use .set_title(), but you can use .set(title=””) .set(ylabel=None) should remove the … Read more