Matplotlib - 2D curve in 3D figure

Question

What is wrong with this command, please?

    ax.plot(xs = 0, y, z, zdir='ÿ́')
                   ^
SyntaxError: positional argument follows keyword argument

then, I tried:

    ax.plot(y, z, xs = 0, zdir='ÿ́')
TypeError: plot() got multiple values for argument 'xs'

I would like to plot a 2D curve y, z on the constant x coordinate. Many thanks

Edit after advice:

How to plot three sine function, each with another constant x, please?

import numpy as np
import matplotlib.pyplot as plt
from mpl_toolkits.mplot3d import Axes3D                         
from mpl_toolkits.mplot3d import proj3d, art3d                     

figsize=[9,4]
fig = plt.figure(figsize=figsize)
ax = fig.add_subplot(111, projection='3d')
ax.azim = -42   # y rotation (default=270)
ax.elev = 0     # x rotation (default=0)

ax.set_xlim(-0.055497704786691616, 0.06545180052052388)
ax.set_ylim(-0.05, 0.55)
ax.set_zlim(-0.05662598667131224, 0.08914572009755688)

plane1 = 0
plane2 = 0.5
h = 0.03

N = 1000
t = np.linspace(plane1, plane2, N)
f = 20
function = h*np.sin(t*f)
x = np.zeros(len(t))

wave_shift = 0.1
# Cycle for generating three sine curve shifted in x
for i in range(3):
    ax.plot(t, function, zdir = 'x')


ax.get_proj = lambda: np.dot(Axes3D.get_proj(ax), np.diag([0.2, 1, 0.13, 1]))

# Text
ax.text3D(0.14, 0.18, -0.08, r'$d$')

margins = {  
    "left"   : -1.5 / figsize[0],
    "bottom" : -9 / figsize[1],
    "right"  : 0.52 + 6 / figsize[0],
    "top"    : 1.5 + 9.3  / figsize[1]
}
fig.subplots_adjust(**margins)

plt.show()

Result now

Desired result:

three same curves, each of them has another x value

Answer 1

First error: "Positional" arguments are those that are determined by their position, ie, in which order within the parenthesis they are listed, such as y, z in your example. "Keyword" arguments are those that you specify which argument it is, such as xs and zdir in your example. Positional arguments must come first, and then you can add on as many keyword arguments as you are able to. That's your first error.

As for the second error, "xs" is here interpreted as a keyword argument. You seem to want to use it as a variable held constant. I think you need to browse the matplotlib plot examples to figure out exactly what you want to be doing.

In the future, a minimum reproducable example is quite helpful, ie, it would help if you could write what your variables xs, y, z are, or better yet make up some example data.