python random walk points are distributed in a straight line and are not random

First time blogging

Express my doubts

 

randomwalk代码
from random import choice

class RandomWalk():
	def __init__(self, num_points=5000):
		self.num_points = num_points
		self.x_values = [0]
		self.y_values = [0]
		
	def fill_walk(self):
		while len(self.x_values) < self.num_points:
			x_direction = choice([-1, 1])
			x_distance = choice([0,1,2,3,4])
			x_step = x_direction * x_distance
			
			y_direction = choice([-1, 1])
			y_distance = choice([0,1,2,3,4])
			y_step =y_direction * y_distance
			
			if x_step == 0 and y_step == 0:
				continue
				
			next_x = self.x_values[-1] + x_step
			next_y = self.x_values[-1] + y_step
			#与列表最后一个值相加
			self.x_values.append(next_x)
			self.y_values.append(next_y)

rw_visual代码
import matplotlib.pyplot as plt
from randomwalk import RandomWalk
while True:
	rw = RandomWalk()
	rw.fill_walk()
	plt.scatter(rw.x_values, rw.y_values, s=1)
	plt.show()
	
	keep_running = input('make another walk?')
	if keep_running == 'n':
		break

Only the most basic ones are left

That's right. I checked it for a long time.

But after running it, it looks like this