transfer from old repo

1 PA Decline/Til DDV/standardise.R

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+## ItMLiHSmar2022
+## standardise.R, child script
+## Data standardisation, returns list
+## Andreas Gammelgaard Damsbo, agdamsbo@clin.au.dk
+
+standardise<-function(train,test,type){
+  # From:
+  # https://datascience.stackexchange.com/questions/13971/standardization-normalization-test-data-in-r
+  
+  sel<-sapply(Xtrain,is.numeric) # Deciding which to stadardise (only numeric)
+  cnm<-colnames(Xtrain) # Saving column names for ordering
+  
+  # Subsetting
+  
+  ## Data to treat
+  train.tr<-train[,sel]
+  test.tr<-test[,sel]
+  
+  ## Data to save
+  train.sv<-train[,!sel]
+  test.sv<-test[,!sel]
+  
+  # Calculate mean and SD of train data
+  trainMean <- sapply(train.tr,mean)
+  trainSd <- sapply(train.tr,sd)
+  
+  if (type=="c"){
+    ## centered
+    norm.trainData<-sweep(train.tr, 2L, trainMean) # using the default "-" to subtract mean column-wise   
+    norm.testData<-sweep(test.tr, 2L, trainMean) # using the default "-" to subtract mean column-wise   
+  }
+ 
+  if (type=="cs"){
+    ## centered AND scaled (Z-score standardisation)
+    norm.trainData<-sweep(sweep(train.tr, 2L, trainMean), 2, trainSd, "/")
+    norm.testData<-sweep(sweep(test.tr, 2L, trainMean), 2, trainSd, "/")
+  }
+  return(list(XtrainSt=cbind(norm.trainData,train.sv)[,cnm], # Reordering columns to original
+              XtestSt=cbind(norm.testData,test.sv)[,cnm]))
+}
+