MetFns (version 1.0)

filter.gc: Selection of visual meteor data by geographical coordinates

Description

Selects data for a given visual meteor dataset and specified geographical coordinates of the observing site or interval of geographical coordinates.

Usage

filter.gc(data, long.low = 0, long.up = 180, ew = c("E", "W"), 
          lat.low = 0, lat.up = 90, ns = c("N", "S"))

Arguments

data

data frame consisting of visual meteor data (rate or magnitude data).

long.low

numeric vector taking a value between 0 (default) and 180, specifying lower boundary of longitude in degrees.

long.up

numeric vector taking a value between 0 and 180 (default), specifying upper boundary of longitude in degrees.

ew

character vector (E,W), specifying east or west position from the prime meridian.

lat.low

numeric vector taking a value between 0 (default) and 90, specifying lower boundary of latitude in degrees.

lat.up

numeric vector taking a value between 0 and 90 (default), specifying upper boundary of latitude in degrees.

ns

character vector (N,S), specifying north or south position from equator.

Value

• filter.gc returns data frame with the same number of columns as the argument data, containing observations corresponding to geographical coordinates with longitude between long.low and long.up and latitude between lat.low and lat.up.

Details

If values of arguments long.low and long.up, as well as lat.low and lat.up, are the same, filter.gc selects data for particular observing site. filter.gc enables one to select data only by longitude or latitude, with geographical coordinates being between given boundaries, less, greater or equal to a boundary.

References

http://www.imo.net/data/visual Rendtel J. and Arlt R., editors (2008). IMO Handbook For Meteor Observers. IMO, Potsdam.

See Also

filter

Examples

## select visual meteor data for 2004, site with longitude 19.7E and latitude 44.2N

## rate data for the year 2004
data(rate04)
filter.gc(rate04,long.low=19.7,long.up=19.7,ew="E",lat.low=44.2,lat.up=44.2,ns="N")

## magnitude data for the year 2004
data(magn04)
filter.gc(magn04,long.low=19.7,long.up=19.7,ew="E",lat.low=44.2,lat.up=44.2,ns="N")


## select visual meteor data corresponding to sites with latitude 44.2N and above
filter.gc(rate04,lat.low=44.2,ns="N")
filter.gc(magn04,lat.low=44.2,ns="N")