Specify marker rotation (in degrees) using the angle aesthetic.
import numpy as np
from lets_plot import *
LetsPlot.setup_html()
data = {
'x': [1, 2, 3, 4],
'y': [1, 1, 1, 1],
'angle': [-30, 0, 30, 60]
}
ggplot(data) +\
geom_point(aes(x='x', y='y', angle='angle'), size=20, shape=13.0) +\
geom_point(x=5, y=1.0, angle=90, size=20, shape=2.0, color='red')