Li

answers.R

@@ -0,0 +1,31 @@
+#challenge 1
+#codes that replicates the functionality of the head function. This code will return the first x lines of file "wages.csv"
+wages = read.csv(file = "wages.csv", header = TRUE)
+x <- 10 #x is the number of rows that will be shown in results; replace 10 by any row numbers for other results
+wages[1:x,] #return the first 10 lines of file "wages.csv"
+
+#challenge 2
+#load file
+read.csv(file = "iris.csv", header = TRUE)
+
+#1. print the last 2 rows in the last 2 columns to the R terminal
+tail(iris[tail(ncol(iris)-1):ncol(iris)], 2)
+
+#2. get the number of observations for each species included in the data set
+unique(iris$Species)
+length(which(iris$Species == 'setosa'))
+length(which(iris$Species == 'versicolor'))
+length(which(iris$Species == 'virginica'))
+
+#3. get rows with Sepal.Width > 3.5
+iris[iris$Sepal.Width > 3.5,]
+
+#4. write the data for the species setosa to a comma-delimited file names ‘setosa.csv’
+setosa <- iris[iris$Species == "setosa",]
+write.table(x=setosa,file="setosa.csv", row.name=FALSE,col.names = TRUE, sep = ",")
+
+#5. calculate the mean, minimum, and maximum of Petal.Length for observations from virginica
+virginica = iris[iris$Species == "virginica",]
+mean(virginica$Petal.Length)
+max(virginica$Petal.Length)
+min(virginica$Petal.Length)

setosa.csv

@@ -0,0 +1,51 @@
+"Sepal.Length","Sepal.Width","Petal.Length","Petal.Width","Species"
+5.1,3.5,1.4,0.2,"setosa"
+4.9,3,1.4,0.2,"setosa"
+4.7,3.2,1.3,0.2,"setosa"
+4.6,3.1,1.5,0.2,"setosa"
+5,3.6,1.4,0.2,"setosa"
+5.4,3.9,1.7,0.4,"setosa"
+4.6,3.4,1.4,0.3,"setosa"
+5,3.4,1.5,0.2,"setosa"
+4.4,2.9,1.4,0.2,"setosa"
+4.9,3.1,1.5,0.1,"setosa"
+5.4,3.7,1.5,0.2,"setosa"
+4.8,3.4,1.6,0.2,"setosa"
+4.8,3,1.4,0.1,"setosa"
+4.3,3,1.1,0.1,"setosa"
+5.8,4,1.2,0.2,"setosa"
+5.7,4.4,1.5,0.4,"setosa"
+5.4,3.9,1.3,0.4,"setosa"
+5.1,3.5,1.4,0.3,"setosa"
+5.7,3.8,1.7,0.3,"setosa"
+5.1,3.8,1.5,0.3,"setosa"
+5.4,3.4,1.7,0.2,"setosa"
+5.1,3.7,1.5,0.4,"setosa"
+4.6,3.6,1,0.2,"setosa"
+5.1,3.3,1.7,0.5,"setosa"
+4.8,3.4,1.9,0.2,"setosa"
+5,3,1.6,0.2,"setosa"
+5,3.4,1.6,0.4,"setosa"
+5.2,3.5,1.5,0.2,"setosa"
+5.2,3.4,1.4,0.2,"setosa"
+4.7,3.2,1.6,0.2,"setosa"
+4.8,3.1,1.6,0.2,"setosa"
+5.4,3.4,1.5,0.4,"setosa"
+5.2,4.1,1.5,0.1,"setosa"
+5.5,4.2,1.4,0.2,"setosa"
+4.9,3.1,1.5,0.2,"setosa"
+5,3.2,1.2,0.2,"setosa"
+5.5,3.5,1.3,0.2,"setosa"
+4.9,3.6,1.4,0.1,"setosa"
+4.4,3,1.3,0.2,"setosa"
+5.1,3.4,1.5,0.2,"setosa"
+5,3.5,1.3,0.3,"setosa"
+4.5,2.3,1.3,0.3,"setosa"
+4.4,3.2,1.3,0.2,"setosa"
+5,3.5,1.6,0.6,"setosa"
+5.1,3.8,1.9,0.4,"setosa"
+4.8,3,1.4,0.3,"setosa"
+5.1,3.8,1.6,0.2,"setosa"
+4.6,3.2,1.4,0.2,"setosa"
+5.3,3.7,1.5,0.2,"setosa"
+5,3.3,1.4,0.2,"setosa"