How to change the head size of the double head annotate in matplotlib?

Question

Below figure shows the plot of which arrow head is very small...

I tried below code, but it didnot work... it said " raise AttributeError('Unknown property %s' % k) AttributeError: Unknown property headwidth"...

xyfrom=[10,620]
xyto=[130,620]
ax.annotate("",xyfrom,xyto,arrowprops=dict(arrowstyle='<->',linewidth = 2,     headwidth=10,color = 'k'
))
ax.text((xyto[0]+xyfrom[0])/2-15,(xyto[1]+xyfrom[1])/2+10,"headwidth is too    small",fontsize=24)

Answer 1

I believe it's because you need to give your arrowstyle arguments inside a string. Try this:

 arrowprops=dict(arrowstyle='<->, head_width=10', facecolor='k')

, notice how this is a full string:

 '<->, head_width=10'

It's a really strange choice in matplotlib, one I really don't understand why should it be this way. In any case see if solves your problem.

Answer 2

... since none of the above answers worked for me... here's my solution:

Use the "mutation_scale" argument! (see doc of FancyArrowPatch )

import matplotlib.pyplot as plt
f, ax = plt.subplots()

ax.scatter([1,2,3,4,5],[1,2,3,4,5])

ann = ax.annotate(rf'small head annotation',
                  xy=(2,2),  xycoords='data',
                  xytext=(.28, .5), textcoords='figure fraction',
                  size=10, va="center", ha="center",
                  bbox=dict(boxstyle="round4", fc="w"),
                  arrowprops=dict(arrowstyle="-|>",mutation_scale=25,
                                  connectionstyle="arc3,rad=-0.2", fc="w"))

ann2 = ax.annotate(rf'BIG head annotation',
                  xy=(2,2),  xycoords='data',
                  xytext=(.75, .15), textcoords='figure fraction',
                  size=10, va="center", ha="center",
                  bbox=dict(boxstyle="round4", fc="w"),
                  arrowprops=dict(arrowstyle="-|>",mutation_scale=50,
                                  connectionstyle="arc3,rad=-0.2", fc="w"))