使用 python 绘制 2D 步行

Question

I am trying to create a very basic walking simulation using python. A random number is generated, determining the direction of each step. I am trying to create a list that contains each y and x coordinate for every step. Something like this: [[0, 0], [1, 0], [0, 0], [0, -1], [-1, -1]]. However, I am having trouble appending the results to the list, making plotting impossible.

Code:

steps = 200

x_c = 0
y_c = 0

walk = [[x_c,y_c]]


for i in range(steps):
        direction = np.random.randint(1,5)
        
        if direction == 1:
            x_c += 1
        if direction == 2:
            x_c -= 1
        if direction == 3:
            y_c += 1
        if direction == 4:
            y_c -= 1
            
        walk = [[x_c,y_c]]

At the moment, the code above produces no errors, but it only plots one point on the graph (0,0), I think I know what the problem is (the list only contains 0,0) but I am not sure how to fix this. Thanks.

Answer 1

It seems like you keep overwriting the items.

The line in the for loop walk = [[x_c,y_c]] just keeps on resetting walk to the current value of x_c,y_c.

Instead use walk.append([x_c,y_c])

steps = 200

x_c = 0
y_c = 0

walk = [[x_c,y_c]]


for i in range(steps):
        direction = np.random.randint(1,5)
        
        if direction == 1:
            x_c += 1
        if direction == 2:
            x_c -= 1
        if direction == 3:
            y_c += 1
        if direction == 4:
            y_c -= 1
            
        walk.append([x_c,y_c])