Read Cartesian points from a CSV and resample at a regular interval with linear interpolation.

resample.py

#!/usr/bin/env python

import bisect, sys

def point(entry):
    return tuple([float(value) for value in entry.split(',')])[0:2]

def normalize(value, max_value):
    return value * (1.0 / max_value)

def bounding_points(x, keys, points):
    i = bisect.bisect(keys, x)
    return (points[i - 1], points[i])

def interpolate(x, ((x0, y0), (x1, y1))):
    return y0 + ((x - x0) * ((y1 - y0) / (x1 - x0)))

def format(x, value):
    return str(x) + '   ' + str(value) + '\n'

with open(sys.argv[2]) as f:
    entries = f.readlines()

num_points = int(sys.argv[1])
points = sorted([point(entry) for entry in entries[2:]], key = lambda point: point[0])
keys = [point[0] for point in points]
normalized_range = [normalize(x, num_points) for x in range(0, num_points)]
interpolated_values = [interpolate(x, bounding_points(x, keys, points)) for x in normalized_range]
output = [format(x, interpolated_values[x]) for x in range(0, num_points)]

with open(sys.argv[3], 'w') as f:
    f.writelines(output)