benchmark: add lines to scatter plots

Adds lines between the points of the same category in scatter.R plots.

PR-URL: #22074
Reviewed-By: Andreas Madsen <amwebdk@gmail.com>
Reviewed-By: Anatoli Papirovski <apapirovski@mac.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>

benchmark/scatter.R

@@ -79,6 +79,7 @@ if (!is.null(plot.filename)) {
     width=.1, na.rm=TRUE
   );
   p = p + geom_point();
+  p = p + geom_line();
   p = p + ylab("rate of operations (higher is better)");
   p = p + ggtitle(dat[1, 1]);
   ggsave(plot.filename, p);

doc/guides/writing-and-running-benchmarks.md

@@ -270,56 +270,64 @@ After generating the csv, a comparison table can be created using the
 the `--plot filename` option.
 
 ```console
-$ cat scatter.csv | Rscript benchmark/scatter.R --xaxis chunk --category encoding --plot scatter-plot.png --log
-
-aggregating variable: inlen
-
-chunk     encoding      mean confidence.interval
-   16        ascii 1111933.3           221502.48
-   16 base64-ascii  167508.4            33116.09
-   16  base64-utf8  122666.6            25037.65
-   16         utf8  783254.8           159601.79
-   64        ascii 2623462.9           399791.36
-   64 base64-ascii  462008.3            85369.45
-   64  base64-utf8  420108.4            85612.05
-   64         utf8 1358327.5           235152.03
-  256        ascii 3730343.4           371530.47
-  256 base64-ascii  663281.2            80302.73
-  256  base64-utf8  632911.7            81393.07
-  256         utf8 1554216.9           236066.53
- 1024        ascii 4399282.0           186436.46
- 1024 base64-ascii  730426.6            63806.12
- 1024  base64-utf8  680954.3            68076.33
- 1024         utf8 1554832.5           237532.07
+$ cat scatter.csv | Rscript benchmark/scatter.R --xaxis chunkLen --category encoding --plot scatter-plot.png --log
+
+aggregating variable: inLen
+
+chunkLen     encoding      rate confidence.interval
+      16        ascii 1515855.1           334492.68
+      16 base64-ascii  403527.2            89677.70
+      16  base64-utf8  322352.8            70792.93
+      16      utf16le 1714567.5           388439.81
+      16         utf8 1100181.6           254141.32
+      64        ascii 3550402.0           661277.65
+      64 base64-ascii 1093660.3           229976.34
+      64  base64-utf8  997804.8           227238.04
+      64      utf16le 3372234.0           647274.88
+      64         utf8 1731941.2           360854.04
+     256        ascii 5033793.9           723354.30
+     256 base64-ascii 1447962.1           236625.96
+     256  base64-utf8 1357269.2           231045.70
+     256      utf16le 4039581.5           655483.16
+     256         utf8 1828672.9           360311.55
+    1024        ascii 5677592.7           624771.56
+    1024 base64-ascii 1494171.7           227302.34
+    1024  base64-utf8 1399218.9           224584.79
+    1024      utf16le 4157452.0           630416.28
+    1024         utf8 1824266.6           359628.52
 ```
 
-Because the scatter plot can only show two variables (in this case _chunk_ and
-_encoding_) the rest is aggregated. Sometimes aggregating is a problem, this
+Because the scatter plot can only show two variables (in this case _chunkLen_
+and _encoding_) the rest is aggregated. Sometimes aggregating is a problem, this
 can be solved by filtering. This can be done while benchmarking using the
 `--set` parameter (e.g. `--set encoding=ascii`) or by filtering results
 afterwards using tools such as `sed` or `grep`. In the `sed` case be
 sure to keep the first line since that contains the header information.
 
 ```console
-$ cat scatter.csv | sed -E '1p;/([^,]+, ){3}128,/!d' | Rscript benchmark/scatter.R --xaxis chunk --category encoding --plot scatter-plot.png --log
-
-chunk     encoding       mean confidence.interval
-   16        ascii  701285.96           21233.982
-   16 base64-ascii  107719.07            3339.439
-   16  base64-utf8   72966.95            2438.448
-   16         utf8  475340.84           17685.450
-   64        ascii 2554105.08           87067.132
-   64 base64-ascii  330120.32            8551.707
-   64  base64-utf8  249693.19            8990.493
-   64         utf8 1128671.90           48433.862
-  256        ascii 4841070.04          181620.768
-  256 base64-ascii  849545.53           29931.656
-  256  base64-utf8  809629.89           33773.496
-  256         utf8 1489525.15           49616.334
- 1024        ascii 4931512.12          165402.805
- 1024 base64-ascii  863933.22           27766.982
- 1024  base64-utf8  827093.97           24376.522
- 1024         utf8 1487176.43           50128.721
+$ cat scatter.csv | sed -E '1p;/([^,]+, ){3}128,/!d' | Rscript benchmark/scatter.R --xaxis chunkLen --category encoding --plot scatter-plot.png --log
+
+chunkLen     encoding      rate confidence.interval
+      16        ascii 1302078.5            71692.27
+      16 base64-ascii  338669.1            15159.54
+      16  base64-utf8  281904.2            20326.75
+      16      utf16le 1381515.5            58533.61
+      16         utf8  831183.2            33631.01
+      64        ascii 4363402.8           224030.00
+      64 base64-ascii 1036825.9            48644.72
+      64  base64-utf8  780059.3            60994.98
+      64      utf16le 3900749.5           158366.84
+      64         utf8 1723710.6            80665.65
+     256        ascii 8472896.1           511822.51
+     256 base64-ascii 2215884.6           104347.53
+     256  base64-utf8 1996230.3           131778.47
+     256      utf16le 5824147.6           234550.82
+     256         utf8 2019428.8           100913.36
+    1024        ascii 8340189.4           598855.08
+    1024 base64-ascii 2201316.2           111777.68
+    1024  base64-utf8 2002272.9           128843.11
+    1024      utf16le 5789281.7           240642.77
+    1024         utf8 2025551.2            81770.69
 ```
 
 ![compare tool boxplot](doc_img/scatter-plot.png)