R Cheatsheet

R Cheatsheet

Get dataframe dimension :

dim(df)

get dataframe row dimension :

nrow(df)

get dataframe col dimension :

ncol(df)

get column names :

names(df)

get column types :

str(df)

get summary of a dataframe :

summary(df)

get top x rows of dataframe:

head(df)

print x'th row and y'th column :

rv=df[x,y]

id=c("a1", "a2", "a3")
marks=c(100, 90, 80)
name=c("rrr", "aaa", "bbb")
age=sample(20:30, 3)
result=c(1,0,0)

df=data.frame(id, marks, name, age, result)
df$result=as.factor(df$result)
print(df)
print(str(df))

Task

Data file :

ID,Name,Marks
a1,a,15
a2,b,13
a3,c,13
a4,d,14
a5,e,14
a6,f,13
a7,g,12
a8,h,11
a9,i,15
a10,j,16

df=read.csv("./grades.csv")
dimensions=dim(df)


even_idx=seq(from = 2, to = nrow(df), by = 2)
even_df=df[even_idx, ]
odd_df=df[-even_idx, ]


train_sample=sample(1:nrow(df), 0.8 * nrow(df), replace = FALSE)

gradetrain=df[train_sample, ]
gradetest=df[-train_sample, ]

print("Dimensions")
print(dimensions)

print("Even df")
print(even_df)
print("Odd df")
print(odd_df)

print("Grade Train")
print(gradetrain)
print("Grade Test")
print(gradetest)


# function chocos
chocos<-function(df) {
    rv=df[,c(1,3)]
    print("Printing 1st and 3rd columns")
    print(rv)

}

chocos(df)