| lookWithin {oce} | R Documentation |
Look Within the First Element of a List for Replacement Values
Description
This is a helper function used by some seawater functions
(with names starting with sw) to
facilitate the specification of water properties either with
distinct arguments, or with data stored within an oce
object that is the first argument.
Usage
lookWithin(list)
Arguments
list |
A list of elements, typically arguments that will be used in sw functions. |
Details
If list[1] is not an oce object, then the
return value of lookWithin is the same as the input
value, except that (a) eos is completed to either
"gsw" or "unesco" and (b) if longitude
and latitude are within list[1], then they
are possibly lengthened, to have the same length as the first
item in the data slot of list[1].
The examples may clarify this somewhat.
Value
A list with elements of the same names but possibly filled in from the first element.
Examples
# 1. If first item is not a CTD object, just return the input
lookWithin(list(a = 1, b = 2)) # returns a list
# 2. Extract salinity from a CTD object
data(ctd)
str(lookWithin(list(salinity = ctd)))
# 3. Extract salinity and temperature. Note that the
# value specified for temperature is ignored; all that matters
# is that temperature is named.
str(lookWithin(list(salinity = ctd, temperature = NULL)))
# 4. How it is used by swRho()
rho1 <- swRho(ctd, eos = "unesco")
rho2 <- swRho(ctd[["salinity"]], ctd[["temperature"]], ctd[["pressure"]], eos = "unesco")
stopifnot(all.equal(rho1, rho2))