format_weather: Format weather data into a standardised format.

In cercospoRa: Process Based Epidemiological Model for Cercospora Leaf Spot of Sugar Beet

Format weather data into a standardised format.

Description

Formats raw weather data into an object suitable for use in the affiliated spore dispersal packages such as ascotraceR and blackspot.sp. This standardised data format ensures that the supplied weather data meet the requirements for functions in the aforementioned packages. Input weather data expects a 'long' data format, where each line is an observation at a point in time.

Usage

format_weather(
  w,
  YYYY = NULL,
  MM = NULL,
  DD = NULL,
  hh = NULL,
  mm = NULL,
  ss = NULL,
  POSIXct_time = NULL,
  time_zone = NULL,
  temp,
  rain,
  rh,
  ws,
  wd,
  wd_sd,
  station,
  lon = NULL,
  lat = NULL,
  lonlat_file = NULL,
  data_check = TRUE
)

Arguments

w	a data.frame object of weather station data for formatting.
YYYY	Column name character or index in w that refers to the year when the weather was logged.
MM	Column name character or index in w that refers to the month (numerical) when the weather was logged.
DD	Column name character or index in w that refers to the day of month when the weather was logged.
hh	Column name character or index in w that refers to the hour (24 hour) when the weather was logged.
mm	Column name character or index in w that refers to the minute when the weather was logged.
ss	Column name character or index in w that refers to the second when the weather was logged.
POSIXct_time	Column name character or index in w which contains a POSIXct formatted time. This can be used instead of arguments YYYY, MM, DD, hh, mm..
time_zone	Time zone (Olsen time zone format) character where the weather station is located. May be in a column or supplied as a character string. Optional, see also r. See details.
temp	Column name character or index in x that refers to temperature in degrees Celsius.
rain	Column name character or index in w that refers to rainfall in millimetres.
rh	Column name character or index in w that refers to relative humidity as a percentage.
ws	Column name character or index in w that refers to wind speed in km / h.
wd	Column name character or index in w that refers to wind direction in degrees.
wd_sd	Column name character or index in w that refers to wind speed columns standard deviation. This is only applicable if weather data is already summarised to hourly increments. See details.
station	Column name character or index in w that refers to the weather station name or identifier. See details.
lon	Column name character or index in w that refers to weather station's longitude. See details.
lat	Column name character or index in w that refers to weather station's latitude. See details.
lonlat_file	A file path (character) to a CSV which included station name/id and longitude and latitude coordinates if they are not supplied in the data. Optional, see also lon and lat.
data_check	If TRUE, it checks for NA values in all 'rain', 'temp', 'rh', 'wd' and 'ws' data and if any values which are unlikely. Use a character vector of variable names, (wither any of 'rain', 'temp', 'rh', 'wd' or 'ws') to check data from specific variables. If FALSE it ignores all variables and could cause subsequent models using this data to fail.

Details

time_zone The time-zone in which the time was recorded. All weather stations in w must fall within the same time-zone. If the required stations are located in differing time zones, format_weather() should be run separately on each object, then data can be combined after formatting.

wd_sd If weather data is provided in hourly increments, a column with the standard deviation of the wind direction over the hour is required to be provided. If the weather data are sub-hourly, the standard deviation will be calculated and returned automatically.

lon, lat and lonlat_file If w provides longitude and latitude values for station locations, these may be specified in the lon and lat columns. If the coordinates are not relevant to the study location NA can be specified and the function will drop these column variables. If these data are not included, (NULL) a separate file may be provided that contains the longitude, latitude and matching station name to provide station locations in the final epiphy.weather object that is created by specifying the file path to a CSV file using lonlat_file.

Value

A epiphy.weather object (an extension of data.table) containing the supplied weather aggregated to each hour in a suitable format for use with disease models. Depending on the input weather, classes will be given to the output object to indicate which models it meets the data requirements for. Some of the columns returned are as follows:

times:	Time in POSIXct format with "UTC" time-zone
rain:	Rainfall in mm
temp:	Temperature in degrees Celsius
ws:	Wind speed in km / h
wd:	Wind direction in compass degrees
wd_sd:	Wind direction standard deviation in compass degrees
lon:	Station longitude in decimal degrees
lat:	Station latitude in decimal degrees
station:	Unique station identifying name
YYYY:	Year
MM:	Month
DD:	Day
hh:	Hour
mm:	Minute

Examples

# load the weather data to be formatted
weather_station_data <-
   read.csv(system.file("extdata",
                        "scaddan_weather.csv",
                        package = "cercospoRa"))
weather_station_data$Local.Time <-
   as.POSIXct(weather_station_data$Local.Time, format = "%Y-%m-%d %H:%M:%S",
              tz = "UTC")

weather <- format_weather(
   w = weather_station_data,
   POSIXct_time = "Local.Time",
   ws = "meanWindSpeeds",
   wd_sd = "stdDevWindDirections",
   rain = "Rainfall",
   temp = "Temperature",
   wd = "meanWindDirections",
   lon = "Station.Longitude",
   lat = "Station.Latitude",
   station = "StationID",
   time_zone = "UTC"
)

# Reformat saved weather

# Create file path and save data
file_path_name <- paste(tempdir(), "weather_saved.csv", sep = "\\")
write.csv(weather, file = file_path_name,
          row.names = FALSE)

# Read data back in to
weather2 <- read.csv(file_path_name, stringsAsFactors = FALSE)

# reformat the data to have appropriate column classes and data class
weather2 <- format_weather(weather2,
                           time_zone = "UTC")
unlink(file_path_name) # remove temporary weather file

cercospoRa documentation built on April 12, 2025, 1:28 a.m.