calculateVariable: Calculate Variable

In bpollner/aquap2: Multivariate Data Analysis Tools for R including Aquaphotomics Methods

Calculate Variable

Description

Calculate values for a new variable.

Usage

calculateVariable(dataset, cexpr = expression(""), name = NULL, type = "c")

Arguments

dataset	The standard dataset as produced by gfd.
cexpr	An arbitrary R expression describing how to calculate the values for the new variable. The expression will be evaluated using 'with', with the local environment being a single row of the provided dataset.
name	Character length one. The name of the new variable.
type	Character length one. The type of the new variable. Possible values are 'c' for class-variables and 'n' for numeric variables. Defaults to '"c"'.

Details

Similarly as combineVariable is simply combining , i.e. pasting together all the values of the selected variables from a single observation (within one row), calculateVariable is using variables of one observation (within one row) to calculate a new value according to the expression provided in the argument 'cexpr'. The expression can contain logical clauses etc, and it pertains exclusively to the values within a single row. Typically, the expression could contain an if clause followed by two values, See examples. New variables of type 'numeric' can obviously only be calculated from numerical variables, but the numeric result of such a calculation can be used as class variable by setting the type of the new variable to 'class' via providing 'c' to the argument 'type'. The name of the new variable and the expression used to calculate it is stored in a list in the slot named 'calcVarInfo'. (object@calcVarInfo)

Value

An object of class 'aquap_data' with a new variable in the header.

See Also

combineVariable

Other dataset modification functions: [,aquap_data-method, combineVariable(), generateMergeLabels,aquap_data,aquap_data,character,character-method, mergeDatasets,aquap_data,aquap_data,missing-method

Examples

## Not run: 
fd <- gfd() # load a dataset
cexpr <- expression(Y_Foo + Y_Bar)
newFd <- calculateVariable(fd, cexpr, name="Addition")
# more examples of how to formulate the expression:
cexpr <- expression((Y_Foo * Y_Bar)/Y_Fuba)
cexpr <- expression(if (Y_Foo < 5 & C_Bar == "blabla") "Outcome1" else "Outcome2")
cexpr <- expression(if (C_Bar == "blabla" | C_Foo == "blibli") "Outcome1" else "Outcome2")
cexpr <- expression(as.numeric(paste0(Y_Foo, C_Bar))/Y_Foobar) # of course crazy, but
# it demonstrates that everything is possible in the expression. 
#
# use a numerical outcome as class variable:
newFd <- calculateVariable(fd, expression(Y_Foo - Y_Bar), name="Subtraction", type="c") 
newFd <- calculateVariable(fd, expression(Y_Foo - Y_Bar), name="Subtraction", type="n") 
# in that way you can color by the result of the calculation, and you 
# can also add the same variable as numerical variable

## End(Not run)

bpollner/aquap2 documentation built on March 29, 2024, 7:33 a.m.