quest (version 0.2.0)

centers_by: Centering and/or Standardizing Numeric Data by Group

Description

centers_by centers and/or standardized data by group. This is sometimes called group-mean centering and/or group-SD standardizing. The groups can be specified by multiple columns in data (e.g., grp.nm with length > 1), and interaction will be implicitly called to create the groups.

Usage

centers_by(data, vrb.nm, grp.nm, center = TRUE, scale = FALSE, suffix)

Value

data.frame of centered and/or standardized variables by group with colnames specified by paste0(vrb.nm, suffix).

Arguments

data

data.frame of data.

vrb.nm

character vector of colnames from data specifying the variables.

grp.nm

character vector of colnames from data specifying the groups.

center

logical vector with length 1 specifying whether group-mean centering should be done.

scale

logical vector with length 1 specifying whether group-SD scaling should be done.

suffix

character vector with a single element specifying the string to append to the end of the colnames of the return object. The default depends on the center and scale arguments: 1)if center = TRUE and scale = FALSE, then suffix = "_cw", 2) if center = FALSE and scale = TRUE, then suffix = "_sw", 3) if center = TRUE and scale = TRUE, then suffix = "_zw", 4) if center = FALSE and scale = FALSE, then suffix = "".

Details

centers_by first coerces data[vrb.nm] to a matrix in preparation for the core of the function, which is essentially lapply(X = split(x = data[vrb.nm], f = data[grp.nm]), FUN = scale.default) If the coercion results in a non-numeric matrix (e.g., any columns in data[vrb.nm] are character vectors or factors), then an error is returned.

See Also

center_by centers center scale.default

Examples

ChickWeight2 <- as.data.frame(ChickWeight) # because the "groupedData" class calls
   # `[.groupedData`, which is different than `[.data.frame`
row.names(ChickWeight2) <- as.numeric(row.names(ChickWeight)) / 1000
centers_by(data = ChickWeight2, vrb.nm = c("weight","Time"), grp.nm = "Chick")
centers_by(data = ChickWeight2, vrb.nm = c("weight","Time"), grp.nm = "Chick",
   scale = TRUE, suffix = "_within")
centers_by(data = as.data.frame(CO2), vrb.nm = c("conc","uptake"),
   grp.nm = c("Type","Treatment"), scale = TRUE) # multiple grouping columns