Answer to Exercise 09

Exercise09Answer.R

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+#set working directory
+setwd("C:Desktop/R Studio Projects/Biocomp_tutorial11")
+
+# define the function 
+cov_function <-function(dir,column_num,nrow=50){
+  data <- list.files(dir)
+  cov <- 0
+
+  for(i in data){
+    table <- read.table(file= i, header=TRUE, sep=",", stringsAsFactors=FALSE)
+    rows <- length(table[,col])
+    if(rows<nrow){
+      input <- readline(prompt=paste("Warning: File has less than 50 observations. Type X to override. Press any other key to go back."))
+      if(input!="X"){
+        sd <- sd(table[,col])
+        mean <- mean(table[,col])
+        cov <- c(cov, sd/mean)
+        cov[-0]
+        return(cov)
+      }
+    }else{
+      sd <- sd(table[,col])
+      mean <- mean(table[,col])
+      cov <- c(cov, sd/mean)
+      cov[-0]
+      return(cov)
+    }
+  }
+}
+
+cov_function(dir="C:Desktop/R studio Projects/Biocomp_tutorial11/", col=4)