What does "rx" or "bx" mean as the third argument of ax.plot?

user_13858293 0
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This code is for KMeans Machine Learning:

from matplotlib import pyplot as plt

fig = plt.figure()
ax = fig.add_subplot()
centroid_colors=['bx','rx']
x = y = [1,2,3]

for color in centroid_colors:
    ax.plot(x, y, color)

what is the meaning of bx, rx here, I can see mentioned as centroid colors, but I could not find these two color code from the color code of matplotlib.

enter image description here

matplotlib python
2 Answers

The third argument is not actually color, but format, including the color, marker style and line style. The syntax of the fmt argument of ax.plot(x,y,fmx) is:

fmt = '[marker][line][color]'

The documentation also gives examples:

'b'    # blue markers with default shape
'or'   # red circles
'-g'   # green solid line
'--'   # dashed line with default color
'^k:'  # black triangle_up markers connected by a dotted line

The bx means "blue x" (i.e. [color][marker]). It seems that the matplotlib plot function is clever enough to understand the fmt even if the ordering of the items in the argument are mixed. The docs say (emphasis mine)

Other combinations such as [color][marker][line] are also supported, but note that their parsing may be ambiguous.

Hence, I would personally use xb over bx.

user_30151860

If you look at the documentation it states that it is the style of marker. In this case a red "x" and a blue "x".

user_59707590
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