Problem

When using pyplot.arrow, the coordinates x, y, dx, dy are within the same coordinate system than the styling kwargs, resulting in different appearances, when used on multiple plots with different scales.

import matplotlib.pyplot as plt

fig, axs = plt.subplots(nrows=3, layout='constrained')

for ii, ax in enumerate(axs.flat):

    ax.set_xlim( [ ii/5, 1 - ii/5 ] )
    ax.set_ylim( [ .5 - (ii+1)/50, .5 + (ii+1)/50 ] )

    ax.arrow( 1 - ii/5, .5, 2 * ii/5 - 1, 0, length_includes_head=True, linewidth=0, width=.01 )

transform=ax.transAxes transforms both, placement and appearance, resulting in homogeneous appearance and hard to handle placement.

Proposed solution

Having coordinates x, y, dx, dy in data coordinates and styling kwargs in axes coordinates.

(And length_includes_head=True as default cough)