Histogram - dots/circle markers

Community matplotlib-users
1

Hello,

Matplotlib is so cool. I wish I had spent time learning it earlier.
Better late than never. Thanks so much to all who have worked on
developing it.

I had a question on histograms. Instead of the bars in case of
histograms, is there a way to get circle markers, where each marker
represents one observation in that bin. For example, if there are 5
observations in a bin, then instead of a bar of height 5, I want 5
circles stacked on top of each other. The same for other bins. Is
there a built-in command or property to do this?

Thanks for your help.

···

On Tue, Feb 8, 2011 at 5:25 AM, sanders <sanders@...3329...> wrote:

Hi,

I want to update the number of columns in my legend. How should I do that?

I'm looking for something like:

fig = plt.figure()
ax = fig.add_subplot(111)
my_own_plot_function(ax, data) # gives, for example, one column legend by
default
legend = ax.get_legend()
legend.set_ncol(2) # something like this

However, ncol is not in the legend.properties() list for properties to be
set through legend.set.

Thanks for any help,
Bram

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2

Not exactly, but you could use numpy’s histogram() function to get the appropriate data and then plot the circles yourself using scatter():

hist, bins = np.histogram(data, bins=20)

fig = plt.figure()
ax = fig.gca()

for left, right, cnt in zip(bins[:-1], bins[1:], hist) :
x = [(left + right) / 2.0] * cnt
y = np.arange(cnt) + 0.5

ax.scatter(x, y, s=np.pi)

plt.show()

You will have to adjust the value of s in the call to scatter to get the desired result. The units of s is points^2. Note that this wouldn’t necessarially “stack” the circles, and zooming in/out of the figure will not change the size of the scatter points. To get more precise control of the circles, you could look into creating the circle patches yourself:

http://matplotlib.sourceforge.net/api/artist_api.html?highlight=circle#matplotlib.patches.Circle

I hope this gets you started!

Ben Root

···

On Tue, Feb 8, 2011 at 6:53 AM, Curiouslearn <curiouslearn@…120…287…> wrote:

Hello,

Matplotlib is so cool. I wish I had spent time learning it earlier.

Better late than never. Thanks so much to all who have worked on

developing it.

I had a question on histograms. Instead of the bars in case of

histograms, is there a way to get circle markers, where each marker

represents one observation in that bin. For example, if there are 5

observations in a bin, then instead of a bar of height 5, I want 5

circles stacked on top of each other. The same for other bins. Is

there a built-in command or property to do this?

Thanks for your help.