How to extract points from a graph?

Question

I have a question.

I have plotted a graph using Matplotlib like this:

from matplotlib import pyplot
import numpy
from scipy.interpolate import spline         


        

Answer 1

You could cast the array to a list:

>>> heights[list(widths).index(30)]
38.5

for the interpolated result:

s = xnew[56] 
print s, heights_smooth[list(xnew).index(s)]
33.7123745819, 40.9547542163

As xnew is an ordered list you could use the bisect module to find a closest width value for a queried width, and then find the corresponding height, in a similar fashion:

....
import bisect
pyplot.plot(xnew,heights_smooth)
#33.1222 is a queried value which does not exist in xnew.
index_of_nearest_width = bisect.bisect_left(xnew, 33.1222) 
width_val = xnew[index_of_closest_width]
print width_val, heights_smooth[list(xnew).index(width_val)]
#prints the nearest width to 33.1222 then the corresponding height.
33.7123745819 40.9547542163