|
1 | 1 | """ |
2 | | -============ |
3 | | -Barcode Demo |
4 | | -============ |
5 | | -
|
6 | | -This demo shows how to produce a one-dimensional image, or "bar code". |
| 2 | +======= |
| 3 | +Barcode |
| 4 | +======= |
| 5 | +This demo shows how to produce a bar code. |
| 6 | +
|
| 7 | +The figure size is calculated so that the width in pixels is a multiple of the |
| 8 | +number of data points to prevent interpolation artifacts. Additionally, the |
| 9 | +``Axes`` is defined to span the whole figure and all ``Axis`` are turned off. |
| 10 | +
|
| 11 | +The data itself is rendered with `~.Axes.imshow` using |
| 12 | +
|
| 13 | +- ``code.reshape(1, -1)`` to turn the data into a 2D array with one row. |
| 14 | +- ``imshow(..., aspect='auto')`` to allow for non-square pixels. |
| 15 | +- ``imshow(..., interpolation='nearest')`` to prevent blurred edges. This |
| 16 | + should not happen anyway because we fine-tuned the figure width in pixels, |
| 17 | + but just to be safe. |
7 | 18 | """ |
| 19 | + |
8 | 20 | import matplotlib.pyplot as plt |
9 | 21 | import numpy as np |
10 | 22 |
|
11 | | -# Fixing random state for reproducibility |
12 | | -np.random.seed(19680801) |
13 | | - |
14 | | -# the bar |
15 | | -x = np.random.rand(500) > 0.7 |
16 | | - |
17 | | -barprops = dict(aspect='auto', cmap='binary', interpolation='nearest') |
18 | | - |
19 | | -fig = plt.figure() |
20 | 23 |
|
21 | | -# a vertical barcode |
22 | | -ax1 = fig.add_axes([0.1, 0.1, 0.1, 0.8]) |
23 | | -ax1.set_axis_off() |
24 | | -ax1.imshow(x.reshape((-1, 1)), **barprops) |
| 24 | +code = np.array([ |
| 25 | + 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 1, 1, 1, |
| 26 | + 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 1, 0, |
| 27 | + 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1, 0, 0, 1, 1, 0, 1, 1, 0, 0, 1, |
| 28 | + 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 0, 1, 0, 0, 0, 1, 0, 0, 1, 0, 1]) |
25 | 29 |
|
26 | | -# a horizontal barcode |
27 | | -ax2 = fig.add_axes([0.3, 0.4, 0.6, 0.2]) |
28 | | -ax2.set_axis_off() |
29 | | -ax2.imshow(x.reshape((1, -1)), **barprops) |
| 30 | +pixel_per_bar = 4 |
| 31 | +dpi = 100 |
30 | 32 |
|
| 33 | +fig = plt.figure(figsize=(len(code) * pixel_per_bar / dpi, 2), dpi=dpi) |
| 34 | +ax = fig.add_axes([0, 0, 1, 1]) # span the whole figure |
| 35 | +ax.set_axis_off() |
| 36 | +ax.imshow(code.reshape(1, -1), cmap='binary', aspect='auto', |
| 37 | + interpolation='nearest') |
31 | 38 | plt.show() |
32 | 39 |
|
33 | 40 | ############################################################################# |
|
43 | 50 | import matplotlib |
44 | 51 | matplotlib.axes.Axes.imshow |
45 | 52 | matplotlib.pyplot.imshow |
| 53 | +matplotlib.figure.Figure.add_axes |
0 commit comments