recall: Recall

In yardstick: Tidy Characterizations of Model Performance

Recall

Description

These functions calculate the recall() of a measurement system for finding relevant documents compared to reference results (the truth regarding relevance). Highly related functions are precision() and f_meas().

Usage

recall(data, ...)

## S3 method for class 'data.frame'
recall(
  data,
  truth,
  estimate,
  estimator = NULL,
  na_rm = TRUE,
  case_weights = NULL,
  event_level = yardstick_event_level(),
  ...
)

recall_vec(
  truth,
  estimate,
  estimator = NULL,
  na_rm = TRUE,
  case_weights = NULL,
  event_level = yardstick_event_level(),
  ...
)

Arguments

data	Either a data.frame containing the columns specified by the truth and estimate arguments, or a table/matrix where the true class results should be in the columns of the table.
...	Not currently used.
truth	The column identifier for the true class results (that is a factor). This should be an unquoted column name although this argument is passed by expression and supports quasiquotation (you can unquote column names). For ⁠_vec()⁠ functions, a factor vector.
estimate	The column identifier for the predicted class results (that is also factor). As with truth this can be specified different ways but the primary method is to use an unquoted variable name. For ⁠_vec()⁠ functions, a factor vector.
estimator	One of: "binary", "macro", "macro_weighted", or "micro" to specify the type of averaging to be done. "binary" is only relevant for the two class case. The other three are general methods for calculating multiclass metrics. The default will automatically choose "binary" or "macro" based on estimate.
na_rm	A logical value indicating whether NA values should be stripped before the computation proceeds.
case_weights	The optional column identifier for case weights. This should be an unquoted column name that evaluates to a numeric column in data. For ⁠_vec()⁠ functions, a numeric vector, hardhat::importance_weights(), or hardhat::frequency_weights().
event_level	A single string. Either "first" or "second" to specify which level of truth to consider as the "event". This argument is only applicable when estimator = "binary". The default uses an internal helper that defaults to "first".

Details

The recall (aka sensitivity) is defined as the proportion of relevant results out of the number of samples which were actually relevant. When there are no relevant results, recall is not defined and a value of NA is returned.

When the denominator of the calculation is 0, recall is undefined. This happens when both ⁠# true_positive = 0⁠ and ⁠# false_negative = 0⁠ are true, which mean that there were no true events. When computing binary recall, a NA value will be returned with a warning. When computing multiclass recall, the individual NA values will be removed, and the computation will procede, with a warning.

Value

A tibble with columns .metric, .estimator, and .estimate and 1 row of values.

For grouped data frames, the number of rows returned will be the same as the number of groups.

For recall_vec(), a single numeric value (or NA).

Relevant Level

There is no common convention on which factor level should automatically be considered the "event" or "positive" result when computing binary classification metrics. In yardstick, the default is to use the first level. To alter this, change the argument event_level to "second" to consider the last level of the factor the level of interest. For multiclass extensions involving one-vs-all comparisons (such as macro averaging), this option is ignored and the "one" level is always the relevant result.

Multiclass

Macro, micro, and macro-weighted averaging is available for this metric. The default is to select macro averaging if a truth factor with more than 2 levels is provided. Otherwise, a standard binary calculation is done. See vignette("multiclass", "yardstick") for more information.

Implementation

Suppose a 2x2 table with notation:

	Reference
Predicted	Relevant	Irrelevant
Relevant	A	B
Irrelevant	C	D

The formulas used here are:

recall = A/(A+C)

precision = A/(A+B)

F_{meas} = (1+\beta^2) * precision * recall/((\beta^2 * precision)+recall)

See the references for discussions of the statistics.

Author(s)

Max Kuhn

References

Buckland, M., & Gey, F. (1994). The relationship between Recall and Precision. Journal of the American Society for Information Science, 45(1), 12-19.

Powers, D. (2007). Evaluation: From Precision, Recall and F Factor to ROC, Informedness, Markedness and Correlation. Technical Report SIE-07-001, Flinders University

See Also

Other class metrics: accuracy(), bal_accuracy(), detection_prevalence(), f_meas(), j_index(), kap(), mcc(), npv(), ppv(), precision(), sens(), spec()

Other relevance metrics: f_meas(), precision()

Examples

# Two class
data("two_class_example")
recall(two_class_example, truth, predicted)

# Multiclass
library(dplyr)
data(hpc_cv)

hpc_cv %>%
  filter(Resample == "Fold01") %>%
  recall(obs, pred)

# Groups are respected
hpc_cv %>%
  group_by(Resample) %>%
  recall(obs, pred)

# Weighted macro averaging
hpc_cv %>%
  group_by(Resample) %>%
  recall(obs, pred, estimator = "macro_weighted")

# Vector version
recall_vec(
  two_class_example$truth,
  two_class_example$predicted
)

# Making Class2 the "relevant" level
recall_vec(
  two_class_example$truth,
  two_class_example$predicted,
  event_level = "second"
)

yardstick documentation built on June 22, 2024, 7:07 p.m.