Answer for Tutorial 9

Tutorial09Answer.R

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+## Problem 1
+
+#define variable with a data file
+allfile<-read.table("file",header=TRUE,sep=",",stringsAsFactors=FALSE)
+#define variable for number of lines to be returned from the top of data1
+returnlines<-allfile[1:n,]
+#Test: output should return first 8 lines from wages.csv
+allfile<-read.table("wages.csv",header=TRUE,sep=",",stringsAsFactors=FALSE)
+returnlines<-allfile[1:8,]
+returnlines
+
+## Problem 2
+
+## Load data from iris.csv 
+iris<-read.table("iris.csv",header=TRUE,sep=",",stringsAsFactors=FALSE)
+
+#Select last two rows in last two columns
+output <- iris[, c(4,5)]
+output
+answer1 <- tail(output, n-2)
+answer1
+
+#get the number of observations for each species included in the data set
+unique(iris$Species)
+sum(iris$Species=="setosa")
+sum(iris$Species=="versicolor")
+sum(iris$Species=="virginica")
+
+#get rows with Sepal.Width > 3.5
+sepalwidth<-iris[,2]
+answer3<-iris[sepalwidth>3.5,]
+
+#write the data for the species setosa to a comma-delimited file names 'setosa.csv'
+species<-iris[,5]
+setosa=iris[species=="setosa",]
+write.table(x=setosa,file="setosa.csv",row.names=FALSE,col.names=TRUE,sep=",")
+
+#calculate the mean, minimum, and maximum of Petal.Length for observations from virginica
+virginica_data=iris[iris[,5]=="virginica",]
+max(virginica_data$Petal.Length)
+min(virginica_data$Petal.Length)
+mean(virginica_data$Petal.Length)