mksub {seas}

Make a subset of seasonal data

Description

Creates a subset of a data.frame with temporal observations, using IDs and start and ending dates or years.

Usage

  mksub(x, start, end, id)

Arguments

x

a data frame with temporal observations

start

either a starting Date or integer year; if omitted minimum will be used

end

either an ending Date or year; if omitted will use same year as start, and if start is omitted, will use maximum year

id

unique station identifier (if present), which is assumed to be a column of x as x$id; it is used to extract a subset of data from a single ID

Details

This utility function is useful for creating temporal subsets of seasonal data and for extracting a single station out of a data.frame with multiple stations or sets. The x object can have many columns, representing measured variables for each day, which will be returned with their original attributes.

If id is used, that station will be extracted from x. If id is not provided, but there are more than one unique IDs in x$id, the first unique ID will be extracted, with a warning.

Value

Returns a subset of a data.frame with the same columns and attributes as x, except id, which will be retained as an attribute (e.g., attr(x,"id")).

Author(s)

Mike Toews

See Also

read.msc, mscdata

Examples

data(mscdata)

# All available data from one station
summary(mksub(mscdata, id=1108447))

# One year
str(mksub(mscdata, id=1108447, start=1980))

# A range of years
str(mksub(mscdata, id=1108447, start=1980, end=1989))

# A range of dates
summary(mksub(mscdata, id=1108447,
              start=as.Date("1975-08-01"),
              end=as.Date("2000-07-31")))