ConvertLongitude: Converts between longitude conventions

In metR: Tools for Easier Analysis of Meteorological Fields

Converts between longitude conventions

Description

Converts longitude from [0, 360) to [-180, 180) and vice versa.

Usage

ConvertLongitude(lon, group = NULL, from = NULL)

Arguments

lon	numeric vector of longitude
group	optional vector of groups (the same length as longitude) that will be split on the edges (see examples)
from	optionally explicitly say from which convention to convert

Value

If group is missing, a numeric vector the same length of lon. Else, a list with vectors lon and group.

Examples

library(ggplot2)
library(data.table)

data(geopotential)

ggplot(geopotential[date == date[1]], aes(lon, lat, z = gh)) +
    geom_contour(color = "black") +
    geom_contour(aes(x = ConvertLongitude(lon)))

map <- setDT(map_data("world"))
map[, c("lon", "group2") := ConvertLongitude(long, group, from = 180)]

ggplot(map, aes(lon, lat, group = group2)) +
    geom_path()

metR documentation built on Oct. 14, 2024, 5:09 p.m.