Q_reps: Stochastic streamflow replicates
In ntthung/shy: Stochastic Hydrology

Description Usage Arguments Details Value

View source: R/generator.R

Generate stochastic replicates of monthly streamflow time series.

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Q_reps(Q.obs, method, order, X.obs = NULL, X.reps = NULL,
  X.name = NULL, X.lag = 0, years = NULL, num.reps = 100,
  trim = 2, Q.trans = "log-std", X.trans = "std")

`Q.obs`	A data frame of observed streamflow with three columns (year, month, Q). By default, the replicates will have the same years as Q.obs, unless `years` is provided.
`method`	Either 'arima' or 'arimax'. 'parma' will be included soon.
`order`	A vector of ARIMA model order. See `forecast::Arima` for details.
`X.obs`	Observed exogeneous input, a data frame with 3 columns (year, month, X). If there are more than 3 columns, the desirable column name to be used as exogenous input should be given in `X.name`; otherwise the function will take the 3th column by default.
`X.reps`	Replicates of X. See ONI_reps.
`X.name`	String, the name of the column used to represent the exogenous input.
`X.lag`	Integer, time lag of X for model fitting
`years`	If provided, the replicates will be indexed by these years.
`num.reps`	Number of replicates to be generated. Default is 100.
`trim`	Used to cut off values that are too high or too low. Values that are more than `trim * max(abs(obs))` will be set to `max(abs(obs))`. Default is 2. Supply `trim = NULL` if you don't want trimming.
`Q.trans`	The pre-processing transformation that will be applied to Q.obs before fitting. log Log-transformation. std Standardization: substracting monthly mean and dividing by monthly standard deviation. log-std First take log-transform, then do standardization.
`X.trans`	Same as `Q.trans` but applied on `X.obs` and `X.reps`.

First, an ARMA or ARMAX model will be fitted using the overlapping period of Q.obs and X.obs. Then, an ARMA model will be fitted using forecast::Arima. Finally, stochastic time series will be generated using stats::simulate.

A data.table with the following collumns: year, month, X (if method == 'armax') and Q.

ntthung/shy documentation built on May 7, 2019, 4:42 p.m.