Galactic love

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The company Astro Logic provides horoscopes to thousands of loyal customers, who each day require a number of divinitions. The most requested is whether or not they should engage in love affairs with a potential partner, who is chosen according to rigourous criteria like his/her astrological sign. You are then hired to devise a fancy visualization which given two astrological signs and their love compatibility, displays the constellations of their signs close when the the compatibility is high and far away when compatibility is low.

Astrology has been dated to at least the 2nd millennium BCE, and has its roots in calendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications. Even if considered a pseudo-science by today standards, it can still provide us with some light-hearted fun while we develop fancy visualizations and matrix manipulations.

What to do

1. Unzip exercises zip in a folder, you should obtain something like this:

galactic-love-prj
    galactic-love.ipynb
    galactic-love-sol.ipynb
    stars.csv
    zodiac.csv
    jupman.py

WARNING: to correctly visualize the notebook, it MUST be in an unzipped folder !

2. open Jupyter Notebook from that folder. Two things should open, first a console and then a browser. The browser should show a file list: navigate the list and open the notebook galactic-love.ipynb

3. Go on reading the notebook, and write in the appropriate cells when asked

Shortcut keys:

• to execute Python code inside a Jupyter cell, press Control + Enter

• to execute Python code inside a Jupyter cell AND select next cell, press Shift + Enter

• to execute Python code inside a Jupyter cell AND a create a new cell aftwerwards, press Alt + Enter

• If the notebooks look stuck, try to select Kernel -> Restart

parse_stars

Let’s start with real astronomical data. You are given a database of constellations called stars.csv (we slightly tweaked it for this occasion - original data source: Space Telescope Science Institute)

import pandas as pd

stars_df = pd.read_csv('stars.csv', encoding='UTF-8')
stars_df[0:32]

	constellation	type	ra	dec	description
0	Andromeda	0	3717	2539	move gamma 1
1	Andromeda	1	2091	2137	draw beta
2	Andromeda	1	1179	1851	draw delta
3	Andromeda	1	251	1745	draw alpha
4	Andromeda	0	1716	1405	move eta
5	Andromeda	1	1420	1456	draw zeta
6	Andromeda	1	1156	1758	draw epsilon
7	Andromeda	1	1179	1851	draw delta
8	Andromeda	1	1106	2023	draw pi
9	Andromeda	1	512	2320	draw theta
10	Andromeda	1	42544	2596	draw iota
11	Andromeda	1	42612	2660	draw kappa
12	Andromeda	1	42526	2787	draw lambda
13	Andromeda	0	42544	2596	move iota
14	Andromeda	1	41457	2539	draw omicron
15	Andromeda	0	1106	2023	move pi
16	Andromeda	1	2091	2137	draw beta
17	Andromeda	1	1702	2309	draw mu
18	Andromeda	1	1494	2464	draw nu
19	Andromeda	1	2085	2834	draw phi
20	Andromeda	1	2939	2917	draw 51
21	Andromeda	-1	0	0	NaN
22	Antlia	0	17077	-2157	move epsilon
23	Antlia	2	18814	-1864	dotted alpha
24	Antlia	2	19701	-2228	dotted iota
25	Antlia	-1	0	0	NaN
26	Apus	0	26635	-4742	move alpha
27	Apus	2	29803	-4733	dotted gamma
28	Apus	2	30092	-4651	dotted beta
29	Apus	2	29410	-4721	dotted delta 1
30	Apus	2	29803	-4733	dotted gamma
31	Apus	-1	0	0	NaN

You will have to parse it so to obtain a dictionary which maps each constellation to its stars, expressed as a list of lists of points type and coordinates.

Since later we will need to show points in a 2d chart, you will have to transform the coordinates obtained from the data (right ascension and declination in degrees) as follows:

\(\large x = \frac{15}{1800}ra\)

\(\large y = \frac{dec}{60}\)

You can find the complete output in expected_stars_db.py

Excerpt:

{'Andromeda': [
                  [0, 30.974999999999998, 42.31666666666666],
                  [1, 17.425, 35.61666666666667],
                  [1, 9.825000000000001, 30.849999999999998],
                  [1, 2.091666666666667, 29.083333333333332],
                  [0, 14.3, 23.416666666666668],
                  [1, 11.833333333333332, 24.266666666666666],
                  [1, 9.633333333333333, 29.3],
                  [1, 9.825000000000001, 30.849999999999998],
                  [1, 9.216666666666667, 33.71666666666667],
                  [1, 4.266666666666667, 38.666666666666664],
                  [1, 354.5333333333333, 43.266666666666666],
                  [1, 355.09999999999997, 44.333333333333336],
                  [1, 354.3833333333333, 46.45],
                  [0, 354.5333333333333, 43.266666666666666],
                  [1, 345.475, 42.31666666666666],
                  [0, 9.216666666666667, 33.71666666666667],
                  [1, 17.425, 35.61666666666667],
                  [1, 14.183333333333334, 38.483333333333334],
                  [1, 12.45, 41.06666666666666],
                  [1, 17.375, 47.233333333333334],
                  [1, 24.491666666666667, 48.61666666666667],
                  [-1, 0.0, 0.0]
               ],
 'Antlia':   [
                  [0, 142.30833333333334, -35.95],
                  [2, 156.78333333333333, -31.066666666666666],
                  [2, 164.175, -37.13333333333333],
                  [-1, 0.0, 0.0]
             ],
  .
  .
  .
}

Show solution

import csv

def parse_stars(filename):


    ret = {}
    with open(filename, encoding='utf-8', newline='') as f:
        my_reader = csv.reader(f, delimiter=',')
        next(my_reader) # skips header
        constellation = ''
        d = None
        for row in my_reader:
            if row[0] != constellation:
                constellation = row[0]
                stars = []
                ret[constellation] = stars
            coords = [0]* 3
            coords[0] = int(row[1])
            coords[1] = int(row[2]) * (1.0 / 1800) * 15
            coords[2] = int(row[3]) * (1.0 / 60)
            stars.append(coords)

    return ret


stars_db = parse_stars('stars.csv')

stars_db['Antlia']
#stars_db['Andromeda']

[[0, 142.30833333333334, -35.95],
 [2, 156.78333333333333, -31.066666666666666],
 [2, 164.175, -37.13333333333333],
 [-1, 0.0, 0.0]]

import csv

def parse_stars(filename):
    raise Exception('TODO IMPLEMENT ME !')

stars_db = parse_stars('stars.csv')

stars_db['Antlia']
#stars_db['Andromeda']

plot_stars 1

Write a function plot_stars to plot constellations.

WARNING: DO NOT use GraphViz!

Even if we are making plots which look like networks, for these visualizations you just need basic matplotlib (and some creativity ;-)

WARNING: for now, ignore the new_center parameter

A point type can either be:

• 0: start a new line not connected with the previous one

• 1: connect previous point with a straight segment

• 2: connect previous point with a dotted segment (draw it with linestyle=':' parameter)

• -1: last point, ignore

Available colorschemes are 'M', 'F', or 'R' (red)

• to set a black background, set plt.rcParams['axes.facecolor'] = 'black'

• draw stars as white dots, setting markersize=6

• to get a nice glowing effect for the lines, draw twice: once with a thick line and dark color, and once with a thin line with a bright color. You can find the colors in color_schemes. To set them in plt.plot call, use linewidth (sets width in pixels) and color parameter, note color takes a single parameter

Examples:

>>> stars_db['Libra']
[[0, 226.01666666666665, -25.266666666666666],
 [1, 222.71666666666667, -16.03333333333333],
 [1, 229.25, -9.366666666666667],
 [1, 233.875, -14.783333333333333],
 [1, 222.71666666666667, -16.03333333333333],
 [0, 233.875, -14.783333333333333],
 [1, 234.25, -28.133333333333333],
 [1, 234.65833333333333, -29.766666666666666],
 [-1, 0.0, 0.0]]

>>> plot_stars('Libra', 'M', stars_db)

>>> stars_db['Cancer']   # has type-2  dotted points
[[0, 131.66666666666669, 28.75],
 [2, 130.8166666666667, 21.466666666666665],
 [2, 131.16666666666666, 18.15],
 [2, 134.61666666666667, 11.85],
 [0, 131.16666666666666, 18.15],
 [2, 124.125, 9.183333333333334],
 [-1, 0.0, 0.0]]

>>> plot_stars("Cancer", 'F', stars_db)

>>> plot_stars("Cygnus", 'M', stars_db)  # mixed segment types

Show solution

%matplotlib inline

import numpy as np
import matplotlib.pyplot as plt

color_schemes = {
    'M': ('blue', '#039dfc'),
    'F': ('purple', 'pink'),
    'R': ('darkred', 'red')
}

def plot_stars(constellation_name, color_scheme, stars, new_center=None):


    plt.rcParams['axes.facecolor'] = 'black'

    color1, color2 = color_schemes[color_scheme]

    point_list = stars[constellation_name]
    points = np.asarray(point_list)
    drawtype = points[:,0]
    ra_degrees = points[:-1,1]
    dec_degrees = points[:-1,2]

    if new_center:
        xbounds = (np.min(ra_degrees), np.max(ra_degrees))
        ybounds = (np.min(dec_degrees), np.max(dec_degrees))
        halfx = (xbounds[1]-xbounds[0])/2
        halfy = (ybounds[1]-ybounds[0])/2

        ra_degrees -= xbounds[0] + halfx - new_center[0]
        dec_degrees -= ybounds[1] - halfy - new_center[1]

    for i in range(0, len(drawtype)-1):
        if drawtype[i] == 0 or drawtype[i] == -1:
            continue

        xs = ra_degrees[i - 1:(i)+1]
        ys = dec_degrees[i - 1:(i)+1]
        plt.plot(xs,ys, linewidth=8, linestyle=':' if drawtype[i] ==2 else "-", color=color1)
        plt.plot(xs,ys, linewidth=3, linestyle=':' if drawtype[i] ==2 else "-", color=color2)
        plt.plot(xs, ys, 'o', markersize=6, color='white')



from pprint import pprint
pprint(stars_db['Libra'])
plot_stars('Libra', 'M', stars_db)

[[0, 226.01666666666665, -25.266666666666666],
 [1, 222.71666666666667, -16.03333333333333],
 [1, 229.25, -9.366666666666667],
 [1, 233.875, -14.783333333333333],
 [1, 222.71666666666667, -16.03333333333333],
 [0, 233.875, -14.783333333333333],
 [1, 234.25, -28.133333333333333],
 [1, 234.65833333333333, -29.766666666666666],
 [-1, 0.0, 0.0]]

%matplotlib inline

import numpy as np
import matplotlib.pyplot as plt

color_schemes = {
    'M': ('blue', '#039dfc'),
    'F': ('purple', 'pink'),
    'R': ('darkred', 'red')
}

def plot_stars(constellation_name, color_scheme, stars, new_center=None):
    raise Exception('TODO IMPLEMENT ME !')

from pprint import pprint
pprint(stars_db['Libra'])
plot_stars('Libra', 'M', stars_db)

pprint(stars_db['Cancer'])   # has type-2  dotted points
plot_stars("Cancer", 'F', stars_db)

plot_stars("Cygnus", 'M', stars_db)  # mixed segment types

plot_stars 2 - new_center

Change the previous function plot_stars so it accepts a new argument new_center, which is either None or a tuple of coordinates where the constellation should be centered:

• be precise in determining the boundaries of the constellation

• DO NOT assume the constallation has a fixed width nor height (so no constants in code!)

Example 1:

fig = plt.figure(figsize=(30,7))
plt.xlim(0,360)
plt.ylim(-40,40)
plot_stars('Gemini', 'F',stars_db, new_center=None)  # no translation

Example 2:

fig = plt.figure(figsize=(30,7))
plt.xlim(0,360)
plt.ylim(-40,40)
plot_stars('Gemini', 'F',stars_db, new_center=(300, -20))  # centered in 300, -20

parse_zodiac

You are given a file zodiac.csv. For each sign, the table contains astrological information and affinity with other signs, expressed as a relation matrix:

import pandas as pd
df = pd.read_csv('zodiac.csv', encoding='UTF-8')
df[:4]

	Constellation	House	Glyph	Symbol	Dates	Element	Quality	Ruling Planet	Day/Night	Aries	...	Gemini	Cancer	Leo	Virgo	Libra	Scorpius	Sagittarius	Capricornus	Aquarius	Pisces
0	Aries	1	♈︎	Ram	21 March\n-\n20 April	Fire	Cardinal	Mars	Day	NaN	...	4.0	NaN	5.0	NaN	NaN	NaN	5.0	NaN	4.0	NaN
1	Taurus	2	♉︎	Bull	21 April\n-\n21 May	Earth	Fixed	Venus	Night	NaN	...	NaN	4.0	NaN	5.0	NaN	NaN	NaN	5.0	NaN	4.0
2	Gemini	3	♊︎	Twins	22 May\n-\n21 June	Air	Mutable	Mercury	Day	4.0	...	NaN	NaN	4.0	NaN	5.0	NaN	NaN	NaN	5.0	NaN
3	Cancer	4	♋︎	Crab	22 June\n-\n21 July	Water	Cardinal	Moon	Night	NaN	...	NaN	NaN	NaN	4.0	NaN	5.0	NaN	NaN	NaN	5.0

4 rows × 21 columns

Parse the table so to get a a dictionary of dictionaries, with some selected data:

• affinities are in the scale 1-5, normalize them to floats 0.0-1.0

• dates contain \n , normalize them so to have dates separated by a dash as in 21 March-20 April

NOTE: To parse the file, a csv.reader is sufficient, it’s not necessary to use pandas - even if data seem to span multiple lines because of the \n in dates, note they are bounded by " so rows will be correctly parsed by csv.reader

You can find the complete output in expected_zodiac_db.py

{
 'Aquarius': {
              'affinities': {
                              'Aries': 0.8,
                              'Gemini': 1.0,
                              'Libra': 1.0,
                              'Sagittarius': 0.8
                             },
              'dates': '21 January-18 February',
              'glyph': '♒︎',
              'house': 11
             },
 'Aries':    {
              'affinities': {
                              'Aquarius': 0.8,
                              'Gemini': 0.8,
                              'Leo': 1.0,
                              'Sagittarius': 1.0
                            },
              'dates': '21 March-20 April',
              'glyph': '♈︎',
              'house': 1
             },
  .
  .
  .
}

Show solution

import csv

def parse_zodiac(filename):

    with open(filename, encoding='utf-8', newline='') as f:
        my_reader = csv.reader(f, delimiter=',')
        header = next(my_reader)

        ret = {}
        for row in my_reader:
            workd = {}
            workd['glyph'] = row[2]
            workd['house'] = int(row[1])
            workd['dates'] = row[4].replace('\n','')
            ret[row[0]] = workd
            workd['affinities'] = {}
            for j in range(9,len(row)):
                if row[j] != '':
                    workd['affinities'][header[j]] = int(row[j])/5
        return ret


zodiac_db = parse_zodiac('zodiac.csv')


from pprint import pprint
#pprint(zodiac_db, width=100)
assert zodiac_db['Aries']['dates'] == '21 March-20 April'
assert zodiac_db['Aries']['affinities'] == {'Aquarius': 0.8, 'Gemini': 0.8, 'Leo': 1.0, 'Sagittarius': 1.0}
assert zodiac_db['Aries']['glyph'] == '♈︎'
assert zodiac_db['Aries']['house'] == 1
assert zodiac_db['Gemini']['dates'] == '22 May-21 June'
assert zodiac_db['Gemini']['affinities'] == {'Aquarius': 1.0, 'Aries': 0.8, 'Leo': 0.8, 'Libra': 1.0}
assert zodiac_db['Gemini']['glyph'] == '♊︎'
assert zodiac_db['Gemini']['house'] == 3
from expected_zodiac_db import expected_zodiac_db
assert zodiac_db == expected_zodiac_db

import csv

def parse_zodiac(filename):
    raise Exception('TODO IMPLEMENT ME !')

zodiac_db = parse_zodiac('zodiac.csv')


from pprint import pprint
#pprint(zodiac_db, width=100)
assert zodiac_db['Aries']['dates'] == '21 March-20 April'
assert zodiac_db['Aries']['affinities'] == {'Aquarius': 0.8, 'Gemini': 0.8, 'Leo': 1.0, 'Sagittarius': 1.0}
assert zodiac_db['Aries']['glyph'] == '♈︎'
assert zodiac_db['Aries']['house'] == 1
assert zodiac_db['Gemini']['dates'] == '22 May-21 June'
assert zodiac_db['Gemini']['affinities'] == {'Aquarius': 1.0, 'Aries': 0.8, 'Leo': 0.8, 'Libra': 1.0}
assert zodiac_db['Gemini']['glyph'] == '♊︎'
assert zodiac_db['Gemini']['house'] == 3
from expected_zodiac_db import expected_zodiac_db
assert zodiac_db == expected_zodiac_db

plot_love

In stars.csv we inserted the special (fake!) constellation of 'Love': given the importance, we placed it at the center of the galaxy, positioned at x=180 degrees and y=0. If you try to plot it now, you should get something like this:

# 'Aries',   'Taurus',   'Gemini',      'Cancer',      'Leo',      'Virgo',
# 'Libra',  'Scorpius',  'Sagittarius', 'Capricornus', 'Aquarius', 'Pisces'

fig = plt.figure(figsize=(30,7))
plt.xlim(0,360)
plot_stars('Gemini','F', stars_db)
plot_stars('Aquarius','M', stars_db)
plot_stars('Love','R', stars_db)    # fake!

Given two astrological signs, place them on the same y=0 axis as the heart and make them symmetrically closer or farther from it according to their astrological affinity, also displaying their name and astrological glyph:

• REMEMBER title and xlabels !

• you can reuse previosly defined plot_stars function

• constellations x centers should go from 50 to 150 degrees (and symmetrically, from -50 to -150)

• BUT you will have to display reversed ticks: 100 50 0 for positive (and symmetrically 0 50 100 for negative)

For drawing text:

• For increasing text size in title, xticks, xlabel, text calls, you can use fontsize=20 parameter (for glyphs you will need a bigger number)

• for text inside the chart use use plt.text(x,y,"some text")

• the glyph must be drawn bigger than the sign name, so you will need a separate call to plt.text

Examples:

>>> plot_love('Gemini','Aquarius', stars_db, zodiac_db)  # 1.0 affinity

>>> plot_love('Gemini','Leo', stars_db, zodiac_db)  # 0.8 affinity

>>> plot_love('Gemini','Taurus', stars_db, zodiac_db) # 0.0 affinity

>>> plot_love('Taurus','Capricornus', stars_db, zodiac_db)  # 1.0 affinity

>>> plot_love('Leo','Libra', stars_db, zodiac_db)  # 0.8 affinity

>>> plot_love('Taurus','Scorpius', stars_db, zodiac_db)  # 0.0 affinity

Show solution

def plot_love(f_sign, m_sign, stars, zodiac):

    fig = plt.figure(figsize=(30,7))  # 30 inches large by 7 high
    plt.xlim(-175,175)




    if m_sign in zodiac[f_sign]['affinities']:
        coeff = zodiac[f_sign]['affinities'][m_sign]
    else:
        coeff = 0.0

    plt.title('GALACTIC LOVE', fontsize=22)
    xs = np.array([50,100,150])
    plt.xlabel('AFFINITY', fontsize=19)
    plt.xticks(np.hstack((-xs,xs)), np.hstack((150-np.abs(xs), 150-np.abs(xs))), fontsize=18)
    plt.ylim(-19,19)
    plot_stars('Love', 'R',stars, new_center=(0,0))
    prox = (1.0 - coeff)*100+25+25
    plot_stars(m_sign, 'M',stars, new_center=(prox,0))
    plot_stars(f_sign, 'F', stars, new_center=(-prox,0))

    plt.text(+prox,-16, m_sign,  fontsize=19,  fontweight='bold', color='white')
    plt.text(+prox-11,-16.5, zodiac[m_sign]['glyph'], fontsize=45,  fontweight='bold', color='white')

    plt.text(-prox,-16, f_sign, fontsize=19,  fontweight='bold', color='white')
    plt.text(-prox-11,-16.5, zodiac[f_sign]['glyph'], fontsize=45,  fontweight='bold', color='white')



plot_love('Gemini','Aquarius', stars_db, zodiac_db)  # 1.0 affinity

def plot_love(f_sign, m_sign, stars, zodiac):

    fig = plt.figure(figsize=(30,7))  # 30 inches large by 7 high
    plt.xlim(-175,175)

    raise Exception('TODO IMPLEMENT ME !')

plot_love('Gemini','Aquarius', stars_db, zodiac_db)  # 1.0 affinity

plot_love('Gemini','Leo', stars_db, zodiac_db)  # 0.8 affinity

plot_love('Gemini','Taurus', stars_db, zodiac_db) # 0.0 affinity

plot_love('Taurus','Capricornus', stars_db, zodiac_db)  # 1.0 affinity

plot_love('Leo','Libra', stars_db, zodiac_db)  # 0.8 affinity

plot_love('Taurus','Scorpius', stars_db, zodiac_db)  # 0.0 affinity