Perks!

install.packages("dplyr")
library(dplyr)

Add “dplyr” package to enable following function

• select()
• filter()
• mutate()
• arrange()
• summarize()
• sample()

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select(variable_name, column_name) → similar like SQL select, can perform column alias, range column name, start/end with column name and exclude column.

df=data.frame( matrix(seq(1, 12), 4, 3) )

select( df, -X1 )
select( df, X2:X3 )
select( df, X2, X3 )
select( df, c("X2", "X3") )

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filter(variable_name, condition) → single or multiple logical condition; similar to subset().

df=data.frame( matrix(seq(1, 12), 4, 3) )

filter( df, X1==1 )
filter( df, X1==1 & X2==5 )
filter( df, X1==1 | X2==4 )

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mutate(variable_name, column_name) → create, edit or delete column (fill value with NULL).

df=data.frame( matrix(seq(1, 12), 4, 3) )

mutate( df, X4=c(1,2,3,4) )

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arrange(variable_name, column_name)

df=data.frame( matrix(seq(1, 12), 4, 3) )

arrange( df, desc(x1) )

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summarize(variable_name, aggregation)

df=data.frame( matrix(seq(1, 12), 4, 3) )

summarize( df, TOTAL=sum(X1) )

sample_n/sample_frac(variable_name, value)

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df=data.frame( matrix(seq(1, 12), 4, 3) )

sample_n( df, 1 )
sample_frac( df, .3 )