README.md

Offset1D: A simple tool for plotting a quantity around a 1D surface

Using a set of points augmented with values of the quantity that is of interest, you can obtain a set of points, representing the graph of the quantity around the surface.

How to use the code

To install the package, just use pip. Download the tar.gz archive from the dist folder in the repository, for example, into your C:/ folder. The you can install the package from the archive:

pip install C:\#archivename.tar.gz

A simple example of the use for the package is following:

import offset1d.getxy as getxy
import math
import random

N = 50
values = [random.uniform(-0.1,0.1) for k in range(N)]
values_on_circle = [(math.cos(k/N*2*math.pi), math.sin(k/N*2*math.pi), values[k]) for k in range(N)]
outline, graph = getxy.surf_and_graph(values_on_circle,scale=0)


import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot(*outline,'black')
ax.plot(*graph,'red')
ax.set_aspect('equal')
plt.show()

You want to use the function surf_and_graph from the getxy module. The order of the points in the list passed to the function matters. The surface is created by connecting the points in the list as ordered in the list. Reversing the order of points does not affect the result.

Scaling

The graph can be scaled around the 1D surface with the scale argument passed to the surf_and_graph function. If 0 is passed as the value (that is done by default), the graph height around the line is kept at the raw values. If scale is set to some positive constant k, the graph is scaled first to its maximum (or minimum) height above the surface to be equal to the surfaces' maximum width or height. Then it is scaled by the scale parameter.

Example of an unscaled graph:

import offset1d.getxy
import math

N = 200

values_on_circle = [
    (
    	math.sin(2*math.cos(k/N*2*math.pi)), 
    	math.sin(k/N*2*math.pi), 
     	0.01*(1+math.cos(k/N*6*math.pi))
    ) for k in range(N)
]
outline, graph = offset1d.getxy.surf_and_graph(values_on_circle)


import matplotlib.pyplot as plt

fig, ax = plt.subplots()
ax.plot(*outline,'black')
ax.plot(*graph,'red')
ax.set_aspect('equal')
plt.show()

You can set the scale to 1:

...
offset1d.getxy.surf_and_graph(values_on_circle, scale=1)
...

The scale is to high for the curve is self-intersecting near the concave parts of the black surface. Smaller scale solves the problem.

...
offset1d.getxy.surf_and_graph(values_on_circle, scale=0.2)
...

Licence

You are free to use or modify the code under the MIT licence.