get_lag_dir function

Get Lag from Input Directory

Given a file path it reads a data frame (time series) of measurements. For each relation file in the provided directory path it calls get_lag_file(). Make sure that the file with Q data and the relation files have the same separator (inputsep) and character for decimal points (inputdec). Gauging station ID's in the relation

files have to be in order of their location in downstream direction. The resulting lags are appended to the relation files. The resulting list of relation files can be returned and each relation file can be saved to its input path.

get_lag_dir(
  Q,
  relation,
  steplength = 15,
  lag.max = 20,
  na.action = na.pass,
  tz = "Etc/GMT-1",
  format = "%Y.%m.%d %H:%M",
  cols = c(1, 2, 3),
  inputsep = ",",
  inputdec = ".",
  relation_pattern = "relation",
  save = FALSE,
  mc.cores = getOption("mc.cores", 2L),
  overwrite = FALSE
)

Arguments

• Q: Data frame or character string. If it is a data frame, it corresponds to the Q data frame in get_lag(). It contains at least a column with the gauging station ID's (default: column index 1), a column with date-time values in character representation (default: column index 2) and a column with flow measurements (default: column index 3). If the column indices differ from c(1, 2, 3), they have to be specified as cols

  argument in the format c(i, j, k). If it is a character string, it contains the path to the corresponding file which is then read within the function with utils::read.csv().

• relation: A character string containing the path to the directory where the relation files are located. They are read within the function with utils::read.csv().

• steplength: Numeric value that specifies the length between time steps in minutes (default: 15 minutes). As time steps have to be equispaced, this is used by hydropeak::flow() to get a compatible format and fill missing time steps with NA.

• lag.max: Maximum lag at which to calculate the ccf in stats::ccf() (default: 20).

• na.action: Function to be called to handle missing values in stats::ccf() (default: na.pass).

• tz: Character string specifying the time zone to be used for internal conversion (default: Etc/GMT-1).

• format: Character string giving the date-time format of the date-time column in the input data frame Q. This is passed to hydropeak::flow(), to get a compatible format (default: YYYY.mm.dd HH:MM).

• cols: Integer vector specifying column indices in the input data frame which contain gauging station ID, date-time and flow rate to be renamed. The default indices are 1 (ID), 2 (date-time) and 3 (flow rate, Q).

• inputsep: Field separator character string for input data.

• inputdec: Character string for decimal points in input data.

• relation_pattern: Character string containing a regular expression to filter relation files (default: relation, to filter files that contain relation with no restriction) (see base::grep()).

• save: A logical. If FALSE (default) the lag, appended to the relation file, overwrites the original relation

  input file.

• mc.cores: Number of cores to use with parallel::mclapply(). On Windows, this is set to 1.

• overwrite: A logical. If FALSE (default), it produces an error if a LAG column already exists in the relation file. Otherwise, it overwrites an existing column.

Returns

Returns invisibly a list of data frames where each list element represents a relation file from the input directory. Optionally, the data frames are used to overwrite the existing relation files with the appended LAG column.

Examples

Q_file <- system.file("testdata", "Q.csv", package = "hydroroute")
relations_path <- system.file("testdata", package = "hydroroute")
lag_list <- get_lag_dir(Q_file, relations_path, inputsep = ",",
                        inputdec = ".", format = "%Y-%m-%d %H:%M",
                        overwrite = TRUE)
lag_list