matplotlib arrow color not work as expected

Question

How to change the arrow color in below demo code?

import matplotlib.pyplot as plt

def save_fig(fig,pngname):
    fig.savefig(pngname, dpi=fig.dpi, bbox_inches="tight")
    print("[[%s]]"%pngname)    
    return

def add_arrow(fig,ax,lw,lc):
    xmin,xmax = ax.get_xlim()
    ax.arrow(xmin,0,xmax-xmin+.2,0,#fc='k', ec='k',
         lw = lw,head_width=.1,head_length=0.4, overhang = 0, 
         length_includes_head=False, clip_on = False,edgecolor='k',facecolor=lc) 
    return

def main():
    x = [
    #"FLAGS",
    "INTENDED_VSYNC",
    "VSYNC",
    "OLDEST_INPUT_EVENT",
    "HANDLE_INPUT_START",
    "ANIMATION_START",
    "PERFORM_TRAVERSALS_START",
    "DRAW_START",
    "SYNC_QUEUED",
    "SYNC_START",
    "ISSUE_DRAW_COMMANDS_START",
    "SWAP_BUFFERS",
    "FRAME_COMPLETED",
   ]

    lw = 2
    lc = "grey"
    fig, ax = plt.subplots(1, figsize=(8,.2))
    y = [0]*len(x)
    ax.plot(x,y,color=lc)

    ax.set_ylim([0,0.1])
    plt.xticks(rotation=45,ha='right')
    ax.tick_params(direction = 'inout',color=lc)
    ax.tick_params('both', length=20, width=lw, which='major')
    ax.tick_params('both', length=10, width=lw, which='minor')
    plt.yticks([], [])
    for direction in ["left", "right", "bottom", "top"]:     
        ax.spines[direction].set_visible(False)
    add_arrow(fig,ax,lw,lc)
    #save_fig(fig,sdir + "/vsync.png")
    plt.show()
    return
sdir = "/home/tester"
main()

Output:

Asked By: lucky1928

||

Source

Answer 1

The color is defined in ax.arrow() by color, edgecolor and facecolor.

edgecolor sets the color of the edge of the arrow.
facecolor sets the color in the arrow body.
color sets the color of both, edgecolor and facecolor.

If you would like to have a uniformly colored arrow, you can either set color to the desired value or alternatively set both, edgecolor and facecolor to the same value. In this case it would mean removing edgecolor and facecolor and adding color=lc or alternatively replacing edgecolor='k' with edgecolor=lc.

import matplotlib.pyplot as plt

def save_fig(fig,pngname):
    fig.savefig(pngname, dpi=fig.dpi, bbox_inches="tight")
    print("[[%s]]"%pngname)    
    return

def add_arrow(fig,ax,lw,lc):
    xmin,xmax = ax.get_xlim()
    ax.arrow(xmin,0,xmax-xmin+.2,0,#fc='k', ec='k',
         lw = lw,head_width=.1,head_length=0.4, overhang = 0, 
         length_includes_head=False, clip_on = False,color=lc) 
    return

def plot():
    x = [
    #"FLAGS",
    "INTENDED_VSYNC",
    "VSYNC",
    "OLDEST_INPUT_EVENT",
    "HANDLE_INPUT_START",
    "ANIMATION_START",
    "PERFORM_TRAVERSALS_START",
    "DRAW_START",
    "SYNC_QUEUED",
    "SYNC_START",
    "ISSUE_DRAW_COMMANDS_START",
    "SWAP_BUFFERS",
    "FRAME_COMPLETED",
   ]

    lw = 2
    lc = "grey"
    fig, ax = plt.subplots(1, figsize=(8,.2))
    y = [0]*len(x)
    ax.plot(x,y,color=lc)

    ax.set_ylim([0,0.1])
    plt.xticks(rotation=45,ha='right')
    ax.tick_params(direction = 'inout',color=lc)
    ax.tick_params('both', length=20, width=lw, which='major')
    ax.tick_params('both', length=10, width=lw, which='minor')
    plt.yticks([], [])
    for direction in ["left", "right", "bottom", "top"]:     
        ax.spines[direction].set_visible(False)
    add_arrow(fig,ax,lw,lc)
    #save_fig(fig,sdir + "/vsync.png")
    plt.show()
    return

plot()

Answered By: fabianegli

matplotlib arrow color not work as expected

Question:

Answers: