How to draw line inside a scatter plot
- by ruffy
I can't believe that this is so complicated but I tried and googled for a while now.
I just want to analyse my scatter plot with a few graphical features.
For starters, I want to add simply a line.
So, I have a few (4) points and like in this plot [1] I want to add a line to it.
http://en.wikipedia.org/wiki/File:ROC_space-2.png [1]
Now, this won't work. And frankly, the documentation-examples-gallery combo and content of matplotlib is a bad source for information.
My code is based upon a simple scatter plot from the gallery:
# definitions for the axes
left, width = 0.1, 0.85 #0.65
bottom, height = 0.1, 0.85 #0.65
bottom_h = left_h = left+width+0.02
rect_scatter = [left, bottom, width, height]
# start with a rectangular Figure
fig = plt.figure(1, figsize=(8,8))
axScatter = plt.axes(rect_scatter)
# the scatter plot:
p1 = axScatter.scatter(x[0], y[0], c='blue', s = 70)
p2 = axScatter.scatter(x[1], y[1], c='green', s = 70)
p3 = axScatter.scatter(x[2], y[2], c='red', s = 70)
p4 = axScatter.scatter(x[3], y[3], c='yellow', s = 70)
p5 = axScatter.plot([1,2,3], "r--")
plt.legend([p1, p2, p3, p4, p5], [names[0], names[1], names[2], names[3], "Random guess"], loc = 2)
# now determine nice limits by hand:
binwidth = 0.25
xymax = np.max( [np.max(np.fabs(x)), np.max(np.fabs(y))] )
lim = ( int(xymax/binwidth) + 1) * binwidth
axScatter.set_xlim( (-lim, lim) )
axScatter.set_ylim( (-lim, lim) )
xText = axScatter.set_xlabel('FPR / Specificity')
yText = axScatter.set_ylabel('TPR / Sensitivity')
bins = np.arange(-lim, lim + binwidth, binwidth)
plt.show()
Everything works, except the p5 which is a line.
Now how is this supposed to work?
What's good practice here?
