findpat {cgwtools}

Function to locate patterns ( sequences of strings or numerical values) in data vectors.

Description

Finds the location of a specified sequence either of numbers or strings in the source data item. If desired, for numerical data, both the source and the named pattern can be rounded to specified number of digits.

Usage

findpat(datavec, pattern, roundit = NULL)

Arguments

datavec

A vector of numerical or string values

pattern

A vector containing the sequence to search for

roundit

If not NULL, sets the precision for rounding numbers. Ignored if datavec are strings

Details

If datavec and pattern are of different types, R will automagically convert to a common type and then compare the values. This is a result of the coercion rules identified in the man page for Comparison, "If the two arguments are atomic vectors of different types, one is coerced to the type of the other, the (decreasing) order of precedence being character, complex, numeric, integer, logical and raw." Use of the roundit argument is recommended whenever working with doubles (floats) to avoid the well-known and often overlooked pain of binary precision errors.

Value

If the first element of pattern isn't found, a message is posted and an empty integer vector is returned. Otherwise, a vector of the indices of datavec where the desired pattern is located is returned. These are the indices of the start of the pattern.

Author(s)

Carl Witthoft, [e-mail]

See Also

which , nth_number_after_mth, strfind

Examples

fooc <- letters[c(1:15,4:9,12:26)]
 findpat(fooc,c('d','e','f'))
# 4 16
fooi <- c(1:50,5:9,60:80)
findpat(fooi,6:8)
# 6 52
findpat(fooi,c('6','7','8'))
# also 6 52