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Summarize data

Source: R/data_summary.R
data_summary.Rd

This function can be used to compute summary statistics for a data frame or a matrix.

Usage

data_summary(x, ...)

# S3 method for class 'data.frame'
data_summary(x, ..., by = NULL, remove_na = FALSE)

Arguments

x

A (grouped) data frame.

...

One or more named expressions that define the new variable name and the function to compute the summary statistic. Example: mean_sepal_width = mean(Sepal.Width). The expression can also be provided as a character string, e.g. "mean_sepal_width = mean(Sepal.Width)". The summary function n() can be used to count the number of observations.

by

Optional character string, indicating the name of a variable in x. If supplied, the data will be split by this variable and summary statistics will be computed for each group.

remove_na

Logical. If TRUE, missing values are omitted from the grouping variable. If FALSE (default), missing values are included as a level in the grouping variable.

Value

A data frame with the requested summary statistics.

Examples

data(iris)
data_summary(iris, MW = mean(Sepal.Width), SD = sd(Sepal.Width))
#>   MW |   SD
#> -----------
#> 3.06 | 0.44
data_summary(
  iris,
  MW = mean(Sepal.Width),
  SD = sd(Sepal.Width),
  by = "Species"
)
#> Species    |   MW |   SD
#> ------------------------
#> setosa     | 3.43 | 0.38
#> versicolor | 2.77 | 0.31
#> virginica  | 2.97 | 0.32

# same as
d <- data_group(iris, "Species")
data_summary(d, MW = mean(Sepal.Width), SD = sd(Sepal.Width))
#> Species    |   MW |   SD
#> ------------------------
#> setosa     | 3.43 | 0.38
#> versicolor | 2.77 | 0.31
#> virginica  | 2.97 | 0.32

# multiple groups
data(mtcars)
data_summary(mtcars, MW = mean(mpg), SD = sd(mpg), by = c("am", "gear"))
#> am | gear |    MW |   SD
#> ------------------------
#>  0 |    3 | 16.11 | 3.37
#>  0 |    4 | 21.05 | 3.07
#>  1 |    4 | 26.27 | 5.41
#>  1 |    5 | 21.38 | 6.66

# expressions can also be supplied as character strings
data_summary(mtcars, "MW = mean(mpg)", "SD = sd(mpg)", by = c("am", "gear"))
#> am | gear |    MW |   SD
#> ------------------------
#>  0 |    3 | 16.11 | 3.37
#>  0 |    4 | 21.05 | 3.07
#>  1 |    4 | 26.27 | 5.41
#>  1 |    5 | 21.38 | 6.66

# count observations within groups
data_summary(mtcars, observations = n(), by = c("am", "gear"))
#> am | gear | observations
#> ------------------------
#>  0 |    3 |           15
#>  0 |    4 |            4
#>  1 |    4 |            8
#>  1 |    5 |            5

# first and last observations of "mpg" within groups
data_summary(
  mtcars,
  first = mpg[1],
  last = mpg[length(mpg)],
  by = c("am", "gear")
)
#> am | gear | first |  last
#> -------------------------
#>  0 |    3 | 21.40 | 19.20
#>  0 |    4 | 24.40 | 17.80
#>  1 |    4 | 21.00 | 21.40
#>  1 |    5 | 26.00 | 15.00