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.

Why would you want to avoid using arrays or lists? Plotting implies that you have a bunch of data points, and trying to manage a bunch of data points without some kind of collection (e.g. an array or list) sounds like one of the lower circles of hell. You could write a plotting library that doesn't allow the caller to use lists, but nobody would want to use it. — Samwise
– Samwise, Commented May 12, 2022 at 22:12

Spec04 · Accepted Answer · 2022-05-14 04:39:34Z

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()

Lineplot

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

edited May 14, 2022 at 4:39

answered May 12, 2022 at 22:48

Spec04

263 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

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

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related