Python single plot in a for loop without creating a list or array

Question

This may sound like a very naive question. However, to me, it's quite fundamental: Can python plot variables without putting them into arrays or lists? I couldn't find much answer on the net or SO and please let me know if there's any duplicate.

I have the following code for demonstration:

import matplotlib.pyplot as plt
import numpy as np

x = 0.0
dx = 0.5

for i in range(10):
    y = x**2
    plt.plot(x,y)
    x += dx

plt.show()


x = np.linspace(-0,.5,10)
y = x**2
plt.plot(x,y)
plt.show()

The first part doesn't plot (which is in an explicit for-loop) anything while the second part does (where both x and y are numpy arrays).

Is it possible to plot without storing variables in arrays or lists? plt.scatter(x,y,c='r') works but that doesn't produce any line plot.

Answer 1

Store the start and end of each segment to iteratively build a series of lines from datapoint to datapoint: (x0,y0) -> (x1, y1)

import matplotlib.pyplot as plt
import numpy as np

x0, y0 = 0, 0
x1 = 0.0
dx = 0.5

for i in range(10):
    y1 = x1**2
    plt.plot([x0,x1],[y0,y1], 'o-')
    x0, y0 = x1, y1
    x1 += dx

plt.show()

Note: this example will draw a line from (0,0) to (0,0) as the x1 value chosen is starting at 0.0