#' This function transforms Z-scores stored in the wide matrix
to measurements using the selector method implemented in
set_refcodes(). It is the inverse of transform2z().
transform2y(
data,
znames = c("hgt_z", "wgt_z", "hdc_z", "wfh_z", "bmi_z", "dsc_z"),
pkg = "nlreferences",
verbose = FALSE,
...
)Data frame with appropriate variables, at least
sex and age. The names of the measurements can
be one or more of: hgt_z, wgt_z, hdc_z, wfh_z, bmi_z and dsc_z.
Character vector containing the names of the Z-scores to convert. Specify this to limit the number of conversions. If not specified, the function calculates measurements for all Z-scores.
Name of the package that stores the growth references. By
default, transform2z searches the nlreferences package.
Set to TRUE to turn on warnings and messages, which is
useful for tracking down problem related to missing data or to the
availability of references.
Arguments passed down to centile::z2y(), e.g. rule = c(1, 2)
to calculate Z-scores beyond the maximum age in the reference table.
A data frame with either zero rows or the same number of rows
as nrow(data) with colums named hgt, wgt, and so on.
By default, the function scans for variables named
hgt_z, wgt_z, hdc_z, wfh_z, bmi_z and dsc_z, and returns
the measurement values for any variables it finds.
The conversion of wfh_z to wfh is special. As wfh is conditional
on hgt, the calculation requires either hgt or hgt_z to be present
in the data. Availability of hgt takes precedence over hgt_z. If
only hgt_z is known, then the function calculates hgt from hgt_z.
df <- data.frame(hgt_z = 0, wgt_z = 1, hdc_z = -1, age = 0.3,
sex = "male", ga = c(20, 30, 40, 50))
transform2y(df, znames = c("hdc_z", "wfh_z"))
#> # A tibble: 4 × 1
#> hdc
#> <dbl>
#> 1 NA
#> 2 37.3
#> 3 40.4
#> 4 40.4