Convert image to desmos graph

img2desmos.py

import numpy as np
import cv2
import matplotlib.pyplot as plt
import code
import time
import sys
from fractions import Fraction

SKIP = 8 if len(sys.argv) <= 3 else int(sys.argv[3])

def chunk(lst, size):
	return [lst[i:i + size] for i in range(0, len(lst), size)]

def seq_to_latex(seq, name, subscript):
	res = f"{name}_{{{subscript}}}=\\left["
	res += ",".join(map(str, seq))
	res += "\\right]"
	return res

def floor_thresh(x, threshold=1e-4):
	if abs(round(x) - x) < threshold:
		return round(x)
	else:
		return x

def eval_fseries(t, amps, freqs, shifts):
	return sum([a*np.cos(f*t + s) for a,f,s in zip(amps,freqs,shifts)])

def fourier_series(vals, time_intv=1):
	fft = np.fft.rfft(vals) / len(vals)
	amps = []
	freqs = []
	shifts = []

	for i in range(len(fft)):
		amp = np.abs(fft[i])
		amps.append(amp)
		freq = 2*np.pi*i / time_intv
		freqs.append(freq)
		shift = np.arctan2(fft[i].imag, fft[i].real)
		shifts.append(shift)
	
	offset = vals[0] - eval_fseries(0, amps, freqs, shifts)
	amps[0] += offset
	amps = list(2*np.array(amps))
	amps[0] -= vals[0]
	
	return amps, freqs, shifts

if __name__ == "__main__":
	im = cv2.imread(sys.argv[1])
	imgray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
	ret,thresh = cv2.threshold(imgray,127,255,0)
	contours, hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
	print("Got contour")

	cnth = [[x for x in list(np.vstack(cnt).squeeze())] for cnt in list(contours)]
	print("Got point list")

	for x in range(len(cnth)):
		if type(cnth[x][0]) != type(np.array([])):
			cnth[x] = [np.array(cnth[x])]

	del contours

	h,w = im.shape[:2]
	cntx = [[a[0] for a in b] for b in cnth] 
	cnty = [[h - a[1] for a in b] for b in cnth]

	del cnth

	print("Got each coordinate")

	sys.stdout = open(sys.argv[2], "w")

	print("C\\left(x,A,F,S\\right)=\\sum_{n=1}^{\\operatorname{length}\\left(A\\right)}\\left(A\\left[n\\right]\\cos\\left(F\\left[n\\right]x+S\\left[n\\right]\\right)\\right)\\left\\{0\\le x\\le1\\right\\}")
	for i in range(0,len(cntx)):
		ampx, freqx, shiftx = fourier_series(cntx[i][::SKIP])
		ampy, freqy, shifty = fourier_series(cnty[i][::SKIP])
		print(seq_to_latex(ampx, "A", f"{i}x"))
		print(seq_to_latex(freqx, "F", f"{i}x"))
		print(seq_to_latex(shiftx, "S", f"{i}x"))
		print(seq_to_latex(ampy, "A", f"{i}y"))
		print(seq_to_latex(freqy, "F", f"{i}y"))
		print(seq_to_latex(shifty, "S", f"{i}y"))
		print(f"\\left(C\\left(t,A_{{{i}x}},F_{{{i}x}},S_{{{i}x}}\\right),C\\left(t,A_{{{i}y}},F_{{{i}y}},S_{{{i}y}}\\right)\\right)")

https://www.desmos.com/calculator/hhzubea2k1