import time
from fractions import Fraction as F
import matplotlib.pyplot as plt

NOW_NS = int(time.time()) * 10 ** 9
THEN_NS = NOW_NS + 5000

plt.title("Comparing conversions over 5 us")


xs = range(NOW_NS, THEN_NS + 1)
y1 = [round(F(x / 10**9) * 10**9) - x for x in xs]
y2 = [int(x / 1e9 * 1e9) - x for x in xs]
y3 = [abs(a) - abs(b) for a, b in zip(y1, y2)]

plt.plot(
    y1,
    drawstyle='steps-mid',
    color="red",
    label="Errors with 'round(F(x / 10**9) * 10**9)'")
plt.plot(
    y2,
    drawstyle='steps-mid',
    color="blue",
    label="Errors with 'int(x / 1e9 * 1e9)'")
plt.plot(
    y3,
    drawstyle='steps-mid',
    color="green",
    label="Comparing absolute errors")
plt.legend()
plt.show()