Custom scatterplot with annotations in Matplotlib

import matplotlib.pyplot as plt
import numpy as np
import pandas as pd

from flexitext import flexitext
from matplotlib.patches import FancyArrowPatch

plt.rcParams.update({"font.family": "Corbel", "font.weight": "light"})
plt.rcParams["text.color"] = "white"
plt.rcParams["axes.labelcolor"] = "white"
plt.rcParams["xtick.labelcolor"] = "white"
plt.rcParams["ytick.labelcolor"] = "white"

url = "https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2020/2020-07-14/astronauts.csv"
data = pd.read_csv(url)
data.head() 

data["age_at_mission"] = data["year_of_mission"] - data["year_of_birth"]

year_of_mission = data["year_of_mission"].values
age_at_mission = data["age_at_mission"].values
sex = data["sex"].values
hours_mission = data["hours_mission"].values
total_number_of_missions = data["total_number_of_missions"].values

DARKBLUE = "#1d1330"
ORANGE = "#ffa72b"
LIGHTBLUE = "#e1f7fa"

def scale(x, lower=0, upper=1):
    return ((x - np.min(x)) / (np.max(x) - np.min(x))) * (upper - lower)  + lower

alpha = scale(total_number_of_missions, 0.1, 1)
sizes = scale(hours_mission, 10, 200)

# Also create an array with the colors
colors = np.where(sex == "male", LIGHTBLUE, ORANGE)

fig, ax = plt.subplots(figsize=(10, 10))

ax.scatter(age_at_mission, year_of_mission);

fig, ax = plt.subplots(figsize=(10, 10))

# Set background color
fig.set_facecolor(DARKBLUE)
ax.set_facecolor(DARKBLUE)

ax.scatter(age_at_mission, year_of_mission, c=colors, s=sizes, alpha=alpha);

# Remove frame (or all the spines at the same time)
ax.set_frame_on(False)

# Customize limits, tick positions, and tick labels for the horizontal axis
ax.set_xlim(10, 85)
ax.set_xticks([20, 40, 60, 80])
ax.set_xticklabels([20, 40, 60, 80], fontsize=10)

# Set a label for the horizontal axis
ax.set_xlabel("Age at start of mission", size=10, weight="light")


# Customize tick positions and tick labels for the vertical axis
ax.set_yticks([1960, 1980, 2000, 2020])
ax.set_yticklabels([1960, 1980, 2000, 2020], fontsize=10)

# Remove tick marks from both axes
ax.tick_params(length=0)

fig

# Adjust figure padding. 
fig.subplots_adjust(top=0.7, bottom=0.08, left=0.06, right=0.94)

# Add title
fig.text(
    0.06, 0.94, "Ages through Time and Space", 
   fontsize=20, fontname="AR DESTINE", va="baseline"
)

# Add subtitle
subtitle = """<size:14><weight:normal>Astronauts have got older, missions have got longer, and starting younger is no guarantee  
of going more often.</> 
  
Each dot is an astronaut on a mission. The larger the dot, the more hours the mission took,  
ranging from 0 to over 10,000 (14 months!). The more transparent the dot, the fewer times  
that astronaut went to space.  

The slope of age by year of mission is similar for <color:#e1f7fa>male</> and <color:#ffa72b>female</> astronauts, with a 20-year  
time lag.  

All this with a few notable exceptions...</>
"""  
flexitext(0.06, 0.91, subtitle, va="top", xycoords="figure fraction", ax=ax)

# Add caption to give appropriate credits to the original author
caption = "#TidyTuesday | Graphic: @cararthompson | Data: Mariya Stavnichuk and Tatsuya Corlett"
fig.text(0.99, 0.01, caption, ha="right", va="bottom", size=9)

fig

text = """<weight:light, size:11>This is not a typo! Meet
<weight:normal>John Herschel Glenn\nJr.</>, who travelled to
space aged 77 in 1999. \nWhat a legend!</>
"""
flexitext(0.9, 0.8, text, ha="center", va="center", ax=ax)


text = """<weight:light, size:11>1985 was the year that,
saw the <weight:normal>most
astronauts in space</>,
with a total of 62 on 28
missions</>.
"""
flexitext(0.825, 0.41, text, ha="center", va="center", ax=ax)

text = """<weight:light, size:11>
The <weight:normal>two youngest
astronauts</> were 
Gherman Titov and
Valentina Tereshkova, 
both aged 26. They
each flew only one
mission. It would be
1982 before the next
female astronaut took
to space.
</>
"""
flexitext(0.02, 0.14, text, va="center", ax=ax)


text = """<weight:light, size:11><weight:normal>Sergei Krikalev</> went on
his first of six missions
aged 30. Only two
astronauts have been
on more missions: 
Franklin R. Chang-Diaz
and Jerry L. Ross, who
both started their
careers in the 1980
NASA-9 selection.</>
""" 
flexitext(0.06, 0.7, text, ax=ax)

fig

# This define the style of the arrow. 
# Play with these values to see how they affect the result.
style = "Simple, tail_width=0.5, head_width=4, head_length=4"

# Straight arrow
arrow = FancyArrowPatch(
    (77, 2005), (77, 1999.5),
    color = "#938ca1",
    arrowstyle = style
)
ax.add_patch(arrow)

# Straight arrow
arrow = FancyArrowPatch(
    (65, 1985), (60, 1985),
    color = "#938ca1",
    arrowstyle = style
)
ax.add_patch(arrow)

# Curved arrow:
# Note the 'connectionstyle' argument.
# The 'rad' value determines the curvature.
arrow = FancyArrowPatch(
    (23, 1965), (34, 1981),
    color = "#ffa72b",
    arrowstyle = style,
    connectionstyle="arc3, rad=0.4",
)
ax.add_patch(arrow)

# Note the negative 'rad' and how it 
# changes the direction of the curvature
arrow = FancyArrowPatch(
    (23, 1970), (26, 1964),
    color = "#938ca1",
    arrowstyle = style,
    connectionstyle="arc3, rad=-0.3",
)
ax.add_patch(arrow)


arrow = FancyArrowPatch(
    (25, 1999), (30, 1989),
    color = "#938ca1",
    arrowstyle = style,
    connectionstyle="arc3, rad=-0.3",
)
ax.add_patch(arrow)

fig

# fig.savefig("plot.png", dpi=400) to save a high quality figure