Scatter3d plot

The scatter3d plot creates a three-dimensional scatter plot of the data.

import plopp as pp
import scipp as sc
import numpy as np

Scatter plot using a positions vector

The easiest way to generate a scatter plot is to use a coordinate of the data array that contains data of the vector3 dtype.

We first generate some fake data, meant to represent clusters of points in a three-dimensional space.

nclusters = 100
npercluster = 1000

position = np.zeros((nclusters, npercluster, 3))
values = np.zeros((nclusters, npercluster))

for n in range(nclusters):
    center = 500.0 * (np.random.random(3) - 0.5)
    r = 20.0 * np.random.normal(size=[npercluster, 3])
    position[n, :] = r + center
    values[n, :] = np.linalg.norm(r, axis=1) + n

da = sc.DataArray(
    data=sc.array(dims=['row'], values=values.flatten(), unit='K'),
    coords={
        'position': sc.vectors(
            dims=['row'], unit='m', values=position.reshape(nclusters * npercluster, 3)
        )
    },
)
da

scipp.DataArray (3.05 MB)

• Dimensions:
  • row: 100000
• Coordinates: (1)
  • position
    (row)
    vector3
    m
    [102.43030748 -63.15660634 170.15779425], [119.94556398 -57.77492152 172.28935367], ..., [-159.57774726 160.48466241 195.95075678], [-163.57709969 182.75237739 203.70362011]

    Values:
    array([[ 102.43030748,  -63.15660634,  170.15779425],
           [ 119.94556398,  -57.77492152,  172.28935367],
           [ 105.84603746,  -32.52227143,  232.50181099],
           ...,
           [-158.8288669 ,  162.9054955 ,  220.08977177],
           [-159.57774726,  160.48466241,  195.95075678],
           [-163.57709969,  182.75237739,  203.70362011]], shape=(100000, 3))

• Data: (1)
  • (row)
    float64
    K
    39.399, 28.431, ..., 110.801, 120.963

    Values:
    array([ 39.39893788,  28.43133739,  52.40526428, ..., 113.38090853,
           110.80144154, 120.96314097], shape=(100000,))

We then simply specify the name of the coordinate that contains the vector positions using the pos argument:

pp.scatter3d(da, pos='position', color='black', size=2)

Scatter plot with colorbar

To make a scatter plot with a colorbar mapping data values to colors, use cbar=True.

pp.scatter3d(da, pos='position', cbar=True, size=2)

Scatter plot using individual coordinates

It is also possible to create scatter plots using three individual coordinate names for the x, y, z dimensions:

time = np.linspace(0, 10, 50)
x = np.cos(time)
y = np.sin(time)

da = sc.DataArray(
    data=sc.array(dims=['row'], values=time),
    coords={
        'x': sc.array(dims=['row'], unit='m', values=x),
        'y': sc.array(dims=['row'], unit='m', values=y),
        'time': sc.array(dims=['row'], unit='s', values=time),
    },
)

pp.scatter3d(da, x='x', y='y', z='time', size=0.2, cbar=True)