spatial_snapshots {stxplore}

Plots spatial snapshots of data through time using a dataframe or a stars object.

Description

This function can take either a stars object or a dataframe. Input arguments differ for each case.

For dataframes, usage involves latitude and longitude. However, x and y coordinates can be given instead of longitude and latitude. If x and y are given instead of longitude and latitude, the country borders will not be shown.

Usage

spatial_snapshots(
  x,
  xlab = "x",
  ylab = "y",
  title = "",
  palette = "Spectral",
  legend_title = "z",
  ...
)

## S3 method for class 'data.frame'
spatial_snapshots(
  x,
  xlab = "Longitude",
  ylab = "Latitude",
  title = "",
  palette = "Spectral",
  legend_title = "z",
  lat_col,
  lon_col,
  t_col,
  z_col,
  ifxy = FALSE,
  ...
)

## S3 method for class 'stars'
spatial_snapshots(
  x,
  xlab = "x",
  ylab = "y",
  title = "",
  palette = "Spectral",
  legend_title = "z",
  ...
)

Arguments

x

A stars object or a dataframe. Arguments differ according to the input type.

xlab

The x label.

ylab

The y label.

title

The graph title.

palette

The color palette. Default is Spectral.

legend_title

The title for the legend.

...

Other arguments currently ignored.

lat_col

For dataframes: the column or the column name giving the latitude. The y coordinate can be used instead of latitude.

lon_col

For dataframes: the column or the column name giving the longitude. The x coordinate can be used instead of longitude.

t_col

For dataframes: the time column. Time must be a set of discrete integer values.

z_col

For dataframes: the The quantity of interest that will be plotted. Eg. temperature.

ifxy

For dataframes: if TRUE then the country borders are not drawn as longitude and latitude are unknown.

Value

A ggplot object.

Examples

library(dplyr)
# Dataframe example
data(NOAA_df_1990)
Tmax <- filter(NOAA_df_1990,
  proc == "Tmax" &
  month == 5 &
  year == 1993 &
  id < 4000)
Tmax$t <- Tmax$julian - min(Tmax$julian) + 1
Tmax_days <- subset(Tmax, t %in% c(1, 15))
spatial_snapshots(Tmax_days,
  lat_col = 'lat',
  lon_col = 'lon',
  t_col = 't',
  z_col = 'z',
  title = "Maximum Temperature for 2 days ")

# stars example
library(stars)
tif = system.file("tif/L7_ETMs.tif", package = "stars")
x <- read_stars(tif)
x2 <- x %>% slice(band, 1:2)
spatial_snapshots(x2)