The prcbench package is a testing workbench for
evaluating precision-recall curves, which requires simple three step
processes to perform evaluations of libraries that create
precision-recall plots.
Tool selection by using the tool interface
Test data selection/creation by using the test data interface
Select pre-defined test data for the accuracy evaluation
Define randomly generated test data for the running-time evaluation
Run a evaluation function with the selected tools and test data sets
Accuracy evaluation of precision-recall curves
Running-time evaluation of precision-recall curves
In addition to predefined tools and test data sets, the
prcbench package provides help functions for users to
define their own tools and datasets.
User-defined test data interface
User-defined test data for the accuracy evaluation
User-defined test data for the running-time evaluation
The prcbench package provides predefined interfaces for
the following five tools that calculate precision-recall curves.
| Tool | Language | Link | 
|---|---|---|
| precrec | R | Tool web site, CRAN | 
| ROCR | R | Tool web site, CRAN | 
| PRROC | R | CRAN | 
| AUCCalculator | Java | Tool web site | 
| PerfMeas | R | CRAN | 
The create_toolset function generates a tool set with a
combination of the five tools.
create_toolset functionThe create_toolset function takes two additional
arguments - calc_auc and store_res.
calc_auc decides whether tools calculate AUC score
or not (Calculation of AUCs are optional for the running-time
evaluation, but not necessary for the evaluation of accurate
precision-recall curves)
store_res decides whether tools store the calculated
curves or not (actual curves are required for the evaluation of accurate
precision-recall curves)
The following six tool sets are predefined with a different combination of tools along with default argument values.
| Set name | Tools | calc_auc | store_res | 
|---|---|---|---|
| def5 | ROCR, AUCCalculator, PerfMeas, PRROC, precrec | TRUE | TRUE | 
| auc5 | ROCR, xAUCCalculator, PerfMeas, PRROC, precrec | TRUE | FALSE | 
| crv5 | ROCR, AUCCalculator, PerfMeas, PRROC, precrec | FALSE | TRUE | 
| def4 | ROCR, AUCCalculator, PerfMeas, precrec | TRUE | TRUE | 
| auc4 | ROCR, AUCCalculator, PerfMeas, precrec | TRUE | FALSE | 
| crv4 | ROCR, AUCCalculator, PerfMeas, precrec | FALSE | TRUE | 
The prcbench package provides two different types of
test data sets.
curve: evaluates the accuracy of precision-recall
curvesbench: measures running times of creating
precision-recall curvesThe create_testset function offers both types of test
data by setting the first argument either as “curve” or “bench”.
The create_testset function takes predefined set names
for curve evaluation. These data sets contain pre-calculated precision
and recall values. The pre-calculated values must be correct so that
they can be compared with the results of specified tools.
The following four test sets are currently available.
| name | #scores&labels | #pos labels | #neg labels | expected #points | expected start | expected end | 
|---|---|---|---|---|---|---|
| c1 | 4 | 2 | 2 | 6 | (0, 1) | (1, 0.5) | 
| c2 | 4 | 2 | 2 | 6 | (0, 0.5) | (1, 0.5) | 
| c3 | 4 | 2 | 2 | 6 | (0, 0) | (1, 0.5) | 
| c4 | 8 | 4 | 4 | 9 | (0, 1) | (1, 0.5) | 
## C1 test set
testset2A <- create_testset("curve", "c1")
## C2 test set
testset2B <- create_testset("curve", "c2")
## Test data sets can be manually combined to a single set
testset2AB <- c(testset2A, testset2B)
## Multiple sets are automatically combined to a single set
testset2C <- create_testset("curve", c("c1", "c2"))The create_testset function uses a naming convention for
randomly generated data for benchmarking. The format is a prefix (‘b’ or
‘i’) followed by the number of dataset. The prefix ‘b’ indicates a
balanced dataset, whereas ‘i’ indicates an imbalanced dataset. The
number can be used with a suffix ‘k’ or ‘m’, indicating respectively
1000 or 1 million.
## A balanced data set with 50 positives and 50 negatives
testset1A <- create_testset("bench", "b100")
## An imbalanced data set with 2500 positives and 7500 negatives
testset1B <- create_testset("bench", "i10k")
## Test data sets can be manually combined to a single set
testset1AB <- c(testset1A, testset1B)
## Multiple sets are automatically combined to a single set
testset1C <- create_testset("bench", c("i10", "b10"))The prcbench package currently provides two different
types of performance evaluation.
Accuracy evaluation of precision-recall curves
Running-time evaluation of precision-recall curves
The run_evalcurve function evaluates precision-recall
curves with the following five test cases. The basic idea is that the
function returns the full score as long as the points generated by a
library matches with the manually calculated recall and precision
values.
| Test case | Description | 
|---|---|
| fpoint | Check the first point | 
| int_pts | Check the intermediate points | 
| epoint | Check the end point | 
| x_range | Evaluate a range between two recall values | 
| y_range | Evaluate a range between two precision values | 
The run_evalcurve function calculates the scores of the
test cases and summarizes them to a data frame.
## Evaluate precision-recall curves for ROCR and precrec with c1 test set
testset <- create_testset("curve", "c1")
toolset <- create_toolset(c("ROCR", "precrec"))
scores <- run_evalcurve(testset, toolset)
scores##   testset toolset toolname score
## 1      c1    ROCR     ROCR   5/8
## 2      c1 precrec  precrec   8/8The result of each test case can be displayed by specifying
data_type = all of the print
function.
##    testset toolset toolname testitem testcat success total
## 1       c1    ROCR     ROCR  x_range      Rg       1     1
## 2       c1    ROCR     ROCR  y_range      Rg       1     1
## 3       c1    ROCR     ROCR   fpoint      SE       0     1
## 4       c1    ROCR     ROCR   intpts      Ip       2     4
## 5       c1    ROCR     ROCR   epoint      SE       1     1
## 6       c1 precrec  precrec  x_range      Rg       1     1
## 7       c1 precrec  precrec  y_range      Rg       1     1
## 8       c1 precrec  precrec   fpoint      SE       1     1
## 9       c1 precrec  precrec   intpts      Ip       4     4
## 10      c1 precrec  precrec   epoint      SE       1     1The autoplot shows a plot with the result of the
run_evalcurve function.
## ggplot2 is necessary to use autoplot
library(ggplot2)
## Plot base points and the result of precrec on c1, c2, and c3 test sets
testset <- create_testset("curve", c("c1", "c2", "c3"))
toolset <- create_toolset("precrec")
scores1 <- run_evalcurve(testset, toolset)
autoplot(scores1)
## Plot the results of PerfMeas and PRROC on c1, c2, and c3 test sets
toolset <- create_toolset(c("PerfMeas", "PRROC"))
scores2 <- run_evalcurve(testset, toolset)
autoplot(scores2, base_plot = FALSE)The run_benchmark function internally calls the
microbenchmark function provided by the microbenchmark
package. It takes a test set and a tool set and returns the result of
microbenchmark.
## Run microbenchmark for aut5 on b10
testset <- create_testset("bench", "b10")
toolset <- create_toolset(set_names = "auc5")
res <- run_benchmark(testset, toolset)
res##   testset toolset      toolname   min    lq  mean median   uq   max neval
## 1     b10    auc5 AUCCalculator 2.235 2.778 5.372  3.053 3.67 15.12     5
## 2     b10    auc5         PRROC 0.166 0.170 0.200  0.176 0.19  0.30     5
## 3     b10    auc5      PerfMeas 0.067 0.069 0.095  0.071 0.08  0.19     5
## 4     b10    auc5          ROCR 1.792 1.821 1.939  1.845 2.01  2.23     5
## 5     b10    auc5       precrec 4.423 4.476 4.590  4.513 4.55  4.99     5In addition to the predefined five tools, users can add new tool
interfaces for their own tools to run benchmarking and curve evaluation.
The create_usrtool function takes a name of the tool and a
function for calculating a precision-recall curve.
## Create a new tool set for 'xyz'
toolname <- "xyz"
calcfunc <- create_example_func()
toolsetU <- create_usrtool(toolname, calcfunc)
## User-defined tools can be combined with predefined tools
toolsetA <- create_toolset("ROCR")
toolsetU2 <- c(toolsetA, toolsetU)Like the predefined tool sets, user-defined tool sets can be used for
both run_benchmark and run_evalcurve.
## Curve evaluation
testset3 <- create_testset("curve", "c2")
scores3 <- run_evalcurve(testset3, toolsetU2)
autoplot(scores3, base_plot = FALSE)The create_example_func function creates an example for
the second argument of the create_usrtool function. The
actual function should also take a testset generated by the
create_testset function and returns a list with three
elements - x, y, and auc.
## function (single_testset) 
## {
##     scores <- single_testset$get_scores()
##     list(x = seq(0, 1, 1/length(scores)), y = seq(0, 1, 1/length(scores)), 
##         auc = 0.5)
## }
## <bytecode: 0x55d06b0319d8>
## <environment: 0x55d06bc0cc00>The create_testset function produces a
testset as either TestDataB or
TestDataC object. See the help files of the R6 classes -
help(TestDataB) and help(TestDataC) - for the
methods that can be used with the precision-recall calculation.
The prcbench package also supports user-defined test
data interfaces. The create_usrdata function creates two
types of test datasets.
User-defined test data for the accuracy evaluation
User-defined test data for the running-time evaluation
The first argument of the create_usrdata function should
be “curve” to create a test dataset for the accuracy evaluation. Scores
and labels as well as pre-calculated recall and precision values are
required. These pre-calculated values are used to compare with the
corresponding values predicted by the specified tools.
## Create a test dataset 'c5' for benchmarking
testsetC <- create_usrdata("curve",
  scores = c(0.1, 0.2), labels = c(1, 0),
  tsname = "c5", base_x = c(0.0, 1.0),
  base_y = c(0.0, 0.5)
)It can be used in the same way as the predefined test datasets
selected by create_testset.
## Run curve evaluation for ROCR and precrec on a predefined test dataset
toolset2 <- create_toolset(c("ROCR", "precrec"))
scores2 <- run_evalcurve(testsetC, toolset2)
autoplot(scores2, base_plot = FALSE)The first argument of the create_usrdata function should
be “bench” to create a test dataset for the running-time evaluation.
Scores and labels are also required.
## Create a test dataset 'b5' for benchmarking
testsetB <- create_usrdata("bench",
  scores = c(0.1, 0.2), labels = c(1, 0),
  tsname = "b5"
)It can be used in the same way as the test datasets generated by
create_testset.
## Run microbenchmark for ROCR and precrec on a predefined test dataset
toolset <- create_toolset(c("ROCR", "precrec"))
res <- run_benchmark(testsetB, toolset)
res##   testset toolset toolname min  lq mean median  uq max neval
## 1      b5    ROCR     ROCR 1.8 1.8  1.9    1.8 1.9 2.2     5
## 2      b5 precrec  precrec 4.5 4.5  4.7    4.6 4.8 5.3     5See our website - Classifier evaluation with imbalanced datasets – for useful tips for performance evaluation on binary classifiers. In addition, we have summarized potential pitfalls of ROC plots with imbalanced datasets. See our paper – The Precision-Recall Plot Is More Informative than the ROC Plot When Evaluating Binary Classifiers on Imbalanced Datasets - for more details.