Fix non-skipped periods from skipped ones

Compute non-skipped periods form start and end of skipped periods.

Usage

skip2noskip(skip = NULL,
               start = NULL,
               end = NULL)

Arguments

skip

A data.frame object with start and end columns that can be coerced to POSIXct. Other columns can be present (and will be ignored). Each row describes a missing period. Rows must be sorted in chronological order and periods should not overlap. Validity checks are at the time very limited.

start

Beginning of the whole period, to be used in as.POSIXct.

end

End of the whole period to be used in as.POSIXct.

Details

In a 'normal' use of this function start and end are given, and are respectively before the beginning of the first skip period and after the end of the last skip period. Thus the returned dataframe will have nrow(skip)+1 rows. However, start and end can be NULL in which case only the nrows(skip)-1 "inner" non-skipped periods will be returned. If start and end are NULL and skip has only one row, the returned result is NULL.

Value

A data.frame object with two POSIXct columns named start and

end. Each row corresponds to a non-skipped period

Author

Yves Deville

See also

readXML for reading data from XML and csv files.

Examples

## Brest data embeds a description of the gaps

ns <- skip2noskip(skip = Brest$OTmissing)

ns2 <- skip2noskip(skip = Brest$OTmissing,
                   start = Brest$OTinfo$start,
                   end = Brest$OTinfo$end)

## check durations. dur2 should be equal to the effective
## duration (with an error of a fraction of day)
dur <- as.numeric(sum(ns$end-ns$start))/365.25
dur2 <- as.numeric(sum(ns2$end-ns2$start))/365.25