Figure 1
Example of efficient stratified sampling graphing. The black line represents a full dataset that is divided into eight subsets. The red line represents the sampled graph that links the maximum and minimum values (red dots) of each subset in their order of appearance.
Figure 2
Flow chart of the efficient stratified sampling graphing method.
Figure 3
Magnified polyline graph.
Figure 4
Comparison of full dataset graphs (a) and sampled graphs (b, c) when the full data are divided into 2X (b) and 1X (c) subsets in 8,640,000 points.
Figure 5
Similarity of nX subsets for sampling with (a) the pixel contrast method, (b) curve area method, and (c) envelope line method. (d) shows the average similarity of 6,000, 60,000, 120,000, 600,000, 2,000,000, and 8,640,000 points.
Table 1
Average similarity of the sampled and full dataset graphs.
| Method | Average similarity (%) of nX subsets for sampling | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1X | 2X | 3X | 4X | 5X | 6X | 8X | 10X | 20X | 30X | 40X | 50X | |
| Pixel contrast method | 96.58 | 99.54 | 98.94 | 99.75 | 99.39 | 99.84 | 99.89 | 99.91 | 99.94 | 99.95 | 99.95 | 99.96 |
| Curve area method | 96.02 | 98.93 | 98.16 | 99.17 | 98.78 | 99.47 | 99.58 | 99.64 | 99.77 | 99.81 | 99.83 | 99.89 |
| Envelope line method | 97.14 | 99.25 | 98.70 | 99.42 | 99.14 | 99.63 | 99.70 | 99.74 | 99.79 | 99.86 | 99.88 | 99.92 |
| Average | 96.58 | 99.24 | 98.60 | 99.44 | 99.11 | 99.65 | 99.72 | 99.76 | 99.83 | 99.87 | 99.89 | 99.93 |
[i] Note: The width and height of the graphing window for the similarity test are 908 and 200 pixels, respectively. When the full dataset is divided into 1X, 3X, and 5X subsets, the similarity is lower; such items are marked in light gray.
Table 2
Sampling graphing speed test result.
| Number of channels | Full dataset capacity (MB) | Full dataset graphing time (s) | Single-thread sampling + graphing | threadPool sampling + graphing | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Sampling time (s) | Graphing time (s) | Total time (s) | Raising rate | Sampling time (s) | Graphing time (s) | Total time (s) | Raising rate | |||
| 3 | 99 | 46 | 0.55 | 0.18 | 0.73 | 63.0 | 0.14 | 0.20 | 0.34 | 135.3 |
| 36 | 1186 | 546 | 6.43 | 1.34 | 7.77 | 70.3 | 1.06 | 1.25 | 2.31 | 236.4 |
| 72 | 2372 | 1072 | 13.04 | 2.69 | 15.73 | 68.2 | 1.98 | 2.51 | 4.49 | 238.8 |
[i] Note: Graphing employs threadPool technology, with one thread per channel; Total time = sampling time + graphing time; Raising rate = Full dataset graphing time/total time.
Figure 6
Concept of gradual scaling control appropriate for sampled graphs.