Plotting histograms, scatter plots in Python

D

Dr. Colombes

What is the easiest way to generate some plots and graphs in Python ?

Specifically interested in simple histograms and scatter plots with
circles and regression lines.

Thanks for your suggestions.
 
F

Fernando Perez

Dr. Colombes said:
What is the easiest way to generate some plots and graphs in Python ?

Specifically interested in simple histograms and scatter plots with
circles and regression lines.

google('matplotlib')
google('gnuplot.py')

hth,

f
 
P

Peter Wilkinson

One module is Matplotlib, that seems to model the Matlab way of doing
things .... its at sourceforge.

Peter W.
 
J

John Hunter

Colombes> What is the easiest way to generate some plots and
Colombes> graphs in Python ? Specifically interested in simple
Colombes> histograms and scatter plots with circles and regression
Colombes> lines.

Here's a little example of a histogram and regression plot using
matplotlib - looks easy enough to me! Output image at
http://nitace.bsd.uchicago.edu:8080/files/share/demo.png

from matplotlib.matlab import *

x = randn(10000) # some gaussian noise

subplot(211) # a subplot
hist(x, 100) # make a histogram
grid(True) # make an axes grid
ylabel('histogram')

# now do the regression...
x = arange(0.0, 2.0, 0.05)
y = 2+ 3*x + 0.2*randn(len(x)) # y is a linear function of x + nse

# the bestfit line from polyfit
m,b = polyfit(x,y,1) # a line is 1st order polynomial...

# plot the data with blue circles and the best fit with a thick
# solid black line
subplot(212)
plot(x, y, 'bo', x, m*x+b, '-k', linewidth=2)
ylabel('regression')
grid(True)

# save the image to hardcopy
savefig('demo')
show()
 
F

Fernando Perez

Colin said:
The charts look good, but the source code links fail.

I found it funny that the author makes a comment about poor PostScript quality
in Gnuplot, touting his as an alternative. If the examples on that page are to
be believed, that stuff looks like low-quality Excel-type business charts,
while Gnuplot has been producing publication quality EPS for a loooong time
(ask the many thousands of scientists using it since the early 90's).

I'd say that matplotlib is the _real_ contender to gnuplot today, not that toy
with horrible font scaling, no apparent real symbol/math support, ugly legend
boxes...

Best,

f
 
D

Dr. Colombes

John, Peter et al:

Thanks very much for your useful tips on MathPlotLib.

I've begun using MatPlotLib and I like it.

Others suggested GnuPlot, which I hope to try sometime in the
future.

Thanks all. This is a good example of very useful information
exchanged over an Internet newsgroup.

Dr. Colombes
 
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Hi

I have plotted Histogram using plplot. Now I want to calculate each(or which) data point falling into each bin of the histogram. How can I do it?

Thanks

~VParekh
 

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