The scope Package. April 19, 2006

Transcription

1 The Package April 19, 2006 Type Package Title Data Manipulation Using Arbitrary Row and Column Criteria Version Date Author Tim Bergsma Maintainer Tim Bergsma Calculate, per data frame row, a value that depends on information in a relevant subset of rows and columns. These functions create and refine objects, which identify relevant rows on a per-row basis. Columns can be aggregated within relevant s to aid identification of a row of interest, from which an arbitrary column value can be selected. License GPL version 2 or newer R topics documented: probe scoop package score skim Inde 7 probe Probe a Data Frame for s Corresponding to a Scoped Aggregate For each row of a data frame, find the value in an arbitrary column and in the row where some other column has the d aggregated value. probe(,, FUN = "ma", that =, = NULL,...) 1

2 2 scoop FUN that A column name in, to which FUN is applied, within. An aggregate function, preferably returning one of its arguments. The column from which to select return values, possibly the same as. A object, identifying rows across which FUN is applied.... Etra arguments to FUN. probe() is a short-cut for a combination of skim(), (), and scoop(). That is, given a data frame and a object, aggregate on one column and use each aggregate value to find the row (if any) where the column value matches; return the value in an arbitrary column for that row. NA is returned if there is not eactly one match for the aggregate. A vector of values of same length and mode as that., score, skim, scoop #What is the time of the maimum concentration within subject (per row)? S <- (Theoph,'Subject') T <- probe(theoph,'conc',that='time',=s) scoop Look Up Column s for Rows In Scope For each vector of row.names in, scoop() will try to retrieve a value from the specified column. If the vector contains eactly one row.name, the corresponding value will be returned. Otherwise, NA is returned. If is not specified, the specified column is returned. scoop(,, = NULL) A column name in, from which values are taken. A object, ideally all elements atomic.

3 3 A vector of same length as the data frame columns, and same mode as., score, skim, probe, #Consider earliest row for each Subject, and return 'conc'. S <- (Theoph,'Subject') S2 <-(Theoph,'Time',that=0,=S) any(score(s2)!=1) scoop(theoph,'conc',=s2) Specify Arbitrary Row Name Subsets Create or refine a list of vectors of row names. Each vector corresponds to a row in a data frame, and its elements identify rows relevant to that row. Relevance is determined by the passed arguments. Refinement consists of passing the output back to the function with further criteria, effectively nesting serial restrictions ( can shrink but not grow). (,, FUN = "==", that = [[]], = NULL) FUN that A column name in, representing the first argument to FUN. A function taking two arguments, typically a comparison operator. A column name in, representing the second argument to FUN; or a vector of same length as columns in ; or an atomic value to be recycled. A object, e.g. created by previous use of. Specifically, a list (same length as columns in ) of vectors of row names in. A data frame and one of its column names must be specified (, ). Defaults are chosen so that if nothing else is specified, per-row will be all rows with the same value of as the row in question. FUN will operate on and that, within, which is all rows, by default. All values of within will be compared to each value of that. If comparison evaluates to TRUE, the corresponding row name is retained in. A list of vectors, one per row in, of relevant row names in.

4 4 -package score, skim, scoop, probe #For each row, consider only those rows with the same Subject S <- (=Theoph, ='Subject', FUN='==', that='subject') #Same effect as... S <- (Theoph,'Subject') #For each row within Subject, consider only those rows having non-zero times. S2 <- (Theoph,'Time','>',0,=S) -package Data Manipulation Using Arbitrary Row and Column Criteria Calculate, per data frame row, a value that depends on information in a relevant subset of rows and columns. These functions create and refine objects, which identify relevant rows on a per-row basis. Columns can be aggregated within relevant s to aid identification of a row of interest, from which an arbitrary column value can be selected. Package: Type: Package Version: Date: License: GPL version 2 or newer Given a data frame of length n, () creates a list of length n, each element of which is a vector of length n or smaller (a object). The vectors hold data frame row names that are selected by some criterion specified as an argument to (). Scope objects may be sequentially refined by passing to () with additional criteria. For a given object, score() returns a vector of the lengths of each element. scoop() effectively dereferences the object, returning a vector of values of a specified column for elements of length one (1). skim() is like tapply(), applying an aggregate function to cells specified by elements. Some aggregate functions are likely to return values that occur once among their arguments (often min() and ma(), but probably not mean()); passing such functions to skim() creates a vector that can be used with () to identify the matching row. probe() is a short-cut that uses skim(), (), and scoop() to find the value in an arbitrary column where the value in a related column matches the aggregated value. Author(s) Tim Bergsma Maintainer: Tim Bergsma <timb@metrumrg.com>

5 score 5 tapply #What is the time since the maimum concentration within subject? Scope <- (Theoph,'Subject') Tma <- probe(theoph,'conc',that='time',=scope) Theoph$SinceMa <- Theoph$Time - Tma score Calculate Lengths of Elements for a Scope Object For each row represented by a object, give the number of row names that are in : i.e. the lengths of the per-row vectors. score() A object, e.g. created by (). This is a useful analytical tool, e.g., for checking whether previous calls to () have limited per-row s to eactly one row name (a condition epected by scoop()). A vector of integers, representing numbers of row names per element in a object., skim, scoop, probe #Consider rows within Subject. S <- (Theoph,'Subject') #How many row names in, per row? min(score(s)) ma(score(s))

6 6 skim skim Aggregate Across Data Frame Subsets Defined by a Scope Object. Apply a function to values in the specified data frame column, across each group of rows specified in the object. skim(,, FUN = "ma", = NULL,...) FUN A column name in, the main argument to FUN. An aggregate function. A object, e.g. created by ().... Etra arguments to pass to FUN. The default is all rows. The default function is ma. Remember that skim() returns a data vector, not a object. For functions that return one of their arguments (perhaps ma and min but perhaps not mean) the result of skim() can be passed back to () to probe for the row from which the value originated. There is a danger that more or fewer than one row will be detected, so check with score(). A vector of same length as giving aggregated values., score, scoop, probe #What is the maimum concentration for each subject? S <- (Theoph,'Subject') m <- skim(theoph,'conc',=s)

7 Inde Topic manip probe, 1 scoop, 2, 3 -package, 4 score, 5 skim, 6 probe, 1, 2, 3, 5, 6 scoop, 2, 2, 3, 5, 6, 2, 3, 5, 6 -package, 4 score, 2, 3, 5, 6 skim, 2, 3, 5, 6 tapply, 4 7