在pyplot中绘制没有y值的x值

Question

Plotting y-values in pyplot is easy, given a list of y_values = [0, 1, 4, 9] , pyplot automatically plots this using

plt.plot(y_values)
plt.show()

As pyplot automatically enumerates these using [0,1,2,3] . However, given a list of x_values , is there a way to automatically plot these without providing y-values? eg let pyplot automatically enumerating them?

I've tried

plt.plot(x=x_values); plt.plot(xdata=x_values)

However none of these seem to work. Of course, one way would be to flip the axes, but is there a simpler way I've overlooked?

Answer 1

The x and y arguments in pyplot.plot(*args, **kwargs) are positional arguments. According to the documentation, eg

plot(x, y)        # plot x and y using default line style and color
plot(x, y, 'bo')  # plot x and y using blue circle markers
plot(y)           # plot y using x as index array 0..N-1

Now, how would pyplot know that if you specify a single argument, you would want it to be interpreted as the ordinate instead of the coordinate? It's simply not possible the way the function is written.

A solution to plot the index against some list is to supply the index as y argument:

import matplotlib.pyplot as plt
x_values = [0, 1, 4, 9]
plt.plot(x_values, range(len(x_values)))
plt.show()