R Coding Basics

setwd("C:/SE")

#working with vectors

#characters:

vChr<-c("One","Two","Three","Four")


#numeric vector
vNum<-c(1,2,3,4)


#creating a data frame
df<-data.frame(vChr,vNum)

head(df)

##    vChr vNum
## 1   One    1
## 2   Two    2
## 3 Three    3
## 4  Four    4

#selecting rows and columns.

#use squared brackets to select x(rows) and y(columns) as in [x,y] 

#select first two rows of df and all columns (a space after the comma means "select all")

df2<-df[1:2,]

#select first three rows and first column:

df3.1<-df[1:3,1]



#subsetting numerics using mathmatical operators
vSub<-subset(df,df$vNum<2)

vSub

##   vChr vNum
## 1  One    1

#subset using "less than or equal to"
vSub1<-subset(df,df$vNum <=2)

vSub1

##   vChr vNum
## 1  One    1
## 2  Two    2

#subsetting with characters
vSub2<-subset(df,df$vChr=="One")

vSub2

##   vChr vNum
## 1  One    1

#subsetting with != ("is not")
vSub3<-subset(df,df$vChr!="Four")


vSub3

##    vChr vNum
## 1   One    1
## 2   Two    2
## 3 Three    3

#using boolean operators "&"(AND) and "|"  (OR)

ANDsub<-subset(df,df$vChr=="One" & df$vNum==1) #AND

ANDsub

##   vChr vNum
## 1  One    1

ORsub<-subset(df,df$vNum==1 | df$vNum==2) #OR

ORsub

##   vChr vNum
## 1  One    1
## 2  Two    2

#saving your workspace to file using the save.image() function - this allows you to load in your results when you start your next R session

save.image(file = "test.RData")

#loading back in
load("test.RData")