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It would be helpful if you read the below post before starting!!

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□ Data filtering using R Studio

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I’ll generate one data.

name=c("Jack","Kate","John","Jane","David","Min","Hyuk","Jisoo")
math=c(90,85,95,75,80,90,90,85)
eng=c(85,90,90,88,95,85,87,88)
country=c("USA","Spain","France","Germany","Netherlands", rep("Korea",3))
gender=c(rep(c("Male","Female"),times=4))
enroll=c(rep(c("Yes","No"),each=4))
grade=data.frame(name,math,eng,country,gender,enroll)
grade

Let’s say this is a math and english score for 8 students from different countries.

Let’s do several things with this data.

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How to delete certain column?

I’d like to delete math column. I use the below code.

grade2=subset(grade, select=-math)
grade2

In case I want to delete both math and eng columns, I use the below code.

grade3=subset(grade,select=c(-math,-eng))
grade3

Without using subset(), we can delete columns using below code.

variable name [-row number, - column number]

For example, If I write a code like grade [, -2] which means I want to delete the 2nd column. In the same way, if I write a code like grade [-2,] which means I want to delete the 2nd row.

grade4=grade[,-2]
grade4

How about delecting both 2nd and 3rd column? The code is below.

grade5=grade[,c(-2,-3)]

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How to select certain column?

Now, I’ll explain how to select certain columns. Now, I’d like to select name, math and country columns.

grade6=subset(grade,select=c(name,math,country))
grade6

or this code will be also possible.

grade7=grade[,c(1,2,4)]
grade7

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