[Matplotlib-users] Combining Linear and Logarithmic Plots

[Derek B. <db...@ya...>]

Hello,

I need to create a Linear Regression plot where the vertices are plotted on a logarithmic plane
and the regression line is plotted on a linear plane. The two are then combined. Here is what I
have so far:

from pylab import *

prediction_experiment = [(313.11000000000001, 25.797999999999998), (4499.1999999999998, 25000.0),
(168830.0, 440000.0), (143090.0, 78571.399999999994), (34811.0, 78571.399999999994), (161240.0,
70967.699999999997)]

def log10Product(x, pos):
    """The two args are the value and tick position.
    Label ticks with the product of the exponentiation"""
    return '%1i' % (x)

def generateLRPlot():
        
    prediction_experiment.sort()
    
    x, y = map(array, zip(*prediction_experiment))
    
    ax = subplot(111)
    
    ax.set_xscale('log')
    ax.set_yscale('log')
        
    formatter = FuncFormatter(log10Product)
    ax.xaxis.set_major_formatter(formatter)
    ax.yaxis.set_major_formatter(formatter)
        
    # the bestfit line from polyfit
    m, b = polyfit(x, y, 1)  # a line is 1st order polynomial...

    plot(x, y, 'b.', x, m*x+b, 'r', linewidth=0.1, markersize=2)
    
    # Must add 1 to allow the last decades label to be shown
    ax.set_xlim(1e-1, max(x)+1)
    ax.set_ylim(1e-1, max(y)+1)
    grid(True)        
    xlabel(r"Prediction", fontsize = 12)
    ylabel(r"Experimental IC50 [nM]", fontsize = 12)
    show()
    # clear the matplotlib figure and axis
    clf()
    cla()
    
generateLRPlot()

Thanks for the help,
Derek Basch

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