R/me.R

In hydroGOF: Goodness-of-Fit Functions for Comparison of Simulated and Observed Hydrological Time Series

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# 'me': Mean Error         #
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#   15-Dic-2008; 06-Sep-09 #
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# 'obs'   : numeric 'data.frame', 'matrix' or 'vector' with observed values
# 'sim'   : numeric 'data.frame', 'matrix' or 'vector' with simulated values
# 'Result': Mean Error between 'sim' and 'obs', in the same units of 'sim' and 'obs' 

me <-function(sim, obs, ...) UseMethod("me")

me.default <- function (sim, obs, na.rm=TRUE, ...){

     
  if ( is.na(match(class(sim), c("integer", "numeric", "ts", "zoo"))) |
          is.na(match(class(obs), c("integer", "numeric", "ts", "zoo")))
     ) stop("Invalid argument type: 'sim' & 'obs' have to be of class: c('integer', 'numeric', 'ts', 'zoo')")    
      
  if ( length(obs) != length(sim) ) 
	 stop("Invalid argument: 'sim' & 'obs' doesn't have the same length !") 
		      
  me <- mean( sim - obs, na.rm = na.rm)           
     
  return(me)
     
  } # 'me.default' end
  
  
me.matrix <- function (sim, obs, na.rm=TRUE, ...){

  # Checking that 'sim' and 'obs' have the same dimensions
  if ( all.equal(dim(sim), dim(obs)) != TRUE )
    stop( paste("Invalid argument: dim(sim) != dim(obs) ( [", 
          paste(dim(sim), collapse=" "), "] != [", 
          paste(dim(obs), collapse=" "), "] )", sep="") )

   me <- colMeans( sim - obs, na.rm= na.rm)  
   
   return(me)
     
  } # 'me' end
  
  
me.data.frame <- function (sim, obs, na.rm=TRUE,...){

   sim <- as.matrix(sim)
   obs <- as.matrix(obs)
	
   me.matrix(sim, obs, na.rm=na.rm, ...)
     
  } # 'me.data.frame' end
  

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# Author: Mauricio Zambrano-Bigiarini                                          #
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# Started: 22-Mar-2013                                                         #
# Updates:                                                                     #
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me.zoo <- function(sim, obs, na.rm=TRUE, ...){
    
    sim <- zoo::coredata(sim)
    if (is.zoo(obs)) obs <- zoo::coredata(obs)
    
    if (is.matrix(sim) | is.data.frame(sim)) {
       me.matrix(sim, obs, na.rm=na.rm, ...)
    } else NextMethod(sim, obs, na.rm=na.rm, ...)
     
  } # 'me.zoo' end