Looking for a program to draw scientific sketches

Question

Does someone know a free program with which i can draw high quality figures for my scientific thesis. I want to draw similar figures like this example

Picture is from: E. Lucon Oscillateurs coupl ́es, d ́esordre et

Answer 1

Python + Matplotlib (possibly used from within Jupyter Notebooks) can generate that sort of diagram at publication quality and in publication suitable formats, all for free and on multiple platforms.

Some Example Code

As starting point, it's not perfect, but you should be able to get the idea:

Cell 1

%matplotlib inline

Cell 2

import matplotlib.pyplot as plt
from matplotlib.patches import Arc, Arrow
import numpy as np
import itertools

Cell 3

def get_circle(x, y, r=1):
    """ Get a cirlce with a specific position and radius"""
    result = plt.Circle((x, y), r, color='k', fill=False)
    return result

def rpoint(x, y, r, deg):
    """ Get a point on a radius at deg degrees."""
    rang = np.deg2rad(deg)
    x1 = x + r * np.sin(rang)
    y1 = y + r * np.cos(rang)
    return (x1, y1)

def radial(x, y, r=1, ang=0, style="-"):
    """ Draw a radial from a given center to the radius and an angle in degrees."""
    x1, y1 = rpoint(x, y, r, ang)
    result = plt.Line2D([x,x1], [y,y1], color='k', linestyle=style)
    return result

def add_arc(x, y, r=1, ang1=0, ang2=0):
    """ Draw the arrow radius."""
    sr = r * 0.75
    x1, y1 = rpoint(x, y, sr, ang2)
    x2, y2 = rpoint(x, y, sr, ang2+15)
    arc = Arc([x, y], sr*2, sr*2, angle=-100, theta1=ang2, theta2=ang1)
    return arc

def add_arrow(x, y, r=1, ang1=0, ang2=0):
    """ Draw the arrow head."""
    sr = r * 0.75
    x1, y1 = rpoint(x, y, sr, ang2)
    x2, y2 = rpoint(x, y, sr, ang2+10)
    arrow = Arrow(x2, y2, x1-x2, y1-y2, color='k', linewidth=0.25)
    return arrow

def add_lables(x, y, r, ang1, ang2, n):
    """ Add the lables."""
    x1, y1 = rpoint(x, y, r*1.21, ang1)
    x2, y2 = rpoint(x, y, r*1.1, ang2)
    text1 = plt.text(x1, y1, rf'$\theta_{n}$')
    text2 = plt.text(x2, y2, rf'$\omega_{n}$')

def add_item(ax, x, y, rad, n, ang1, ang2, theta_ang):
    """ Add a single item."""
    ax.add_patch(get_circle(x, y, rad))
    ax.add_artist(radial(x, y, rad, ang1))
    ax.add_artist(radial(x, y, rad, ang2, '--'))
    ax.add_patch(add_arc(x, y, rad, ang1, ang2))
    ax.add_patch(add_arrow(x, y, rad, ang1, ang2))

    add_lables(x, y, rad, (ang1+ang2)/2, theta_ang, n)

Cell 4

fig, ax = plt.subplots()

centx, centy = 120, 120
radius = 30
item_rad = 9
item_count = 6
step = 360/item_count
offset = step/2
item_angs = [offset+step*n for n in range(item_count)]
#print(item_angs)
itemxys = [rpoint(centx, centy, radius, item_angs[n]) for n in range(item_count)]
items = [(*p, item_angs[n], n) for n,p in enumerate(itemxys)]
#print(items)

for x, y, ang, n in items:
    add_item(ax, x, y, item_rad, n, 145, 45, ang-offset)

for xy1, xy2 in itertools.combinations(itemxys, 2):
    ax.add_artist(plt.Line2D([xy1[0], xy2[0]], [xy1[1], xy2[1]], color='lightgrey', linestyle=':'))

ax.set_aspect('equal', adjustable='datalim')
ax.axes.get_xaxis().set_visible(False)
ax.axes.get_yaxis().set_visible(False)
ax.plot()
plt.savefig('demo.svg')
plt.savefig('demo.png')
plt.savefig('demo.pdf')

Results in:

O.K I haven't varied the angles, the label offsets need more work, etc., but I think this is a good starting point. All of the information I used to get this far was either in the matplotlib manuals or examples.

The above code is available in a GitHub gist: https://gist.github.com/GadgetSteve/557b7c995a824af92f455f5f475948d5