CYLINDER AREA

cylinder<-function(r,h){area<-2*pi*r*h+2*pi*r^2
return(area)}
cylinder(2,3)
## [1] 62.83185
cylinder(1:6,12:17)
## [1]  81.68141 188.49556 320.44245 477.52208 659.73446 867.07957
cylinder<-function(r,h){area<-2*pi*r*h+2*pi*r^2
return(c(r,h,area))}
cylinder(2,3)
## [1]  2.00000  3.00000 62.83185
cylinder(1:6,12:17)
##  [1]   1.00000   2.00000   3.00000   4.00000   5.00000   6.00000  12.00000
##  [8]  13.00000  14.00000  15.00000  16.00000  17.00000  81.68141 188.49556
## [15] 320.44245 477.52208 659.73446 867.07957
cylinder<-function(r,h){area<-2*pi*r*h+2*pi*r^2
return(cbind(r,h,area))}
cylinder(2,3)
##      r h     area
## [1,] 2 3 62.83185
cylinder(1:6,12:17)
##      r  h      area
## [1,] 1 12  81.68141
## [2,] 2 13 188.49556
## [3,] 3 14 320.44245
## [4,] 4 15 477.52208
## [5,] 5 16 659.73446
## [6,] 6 17 867.07957

IFELSE

data(cars)
head(cars)
library(ggplot2)
library(dplyr)
## 
## Attaching package: 'dplyr'
## The following objects are masked from 'package:stats':
## 
##     filter, lag
## The following objects are masked from 'package:base':
## 
##     intersect, setdiff, setequal, union
cars<-cars%>%mutate(color=ifelse(speed<14,"blue",ifelse(speed>14,"red","black")))
head(cars)
summary(cars)
##      speed           dist           color          
##  Min.   : 4.0   Min.   :  2.00   Length:50         
##  1st Qu.:12.0   1st Qu.: 26.00   Class :character  
##  Median :15.0   Median : 36.00   Mode  :character  
##  Mean   :15.4   Mean   : 42.98                     
##  3rd Qu.:19.0   3rd Qu.: 56.00                     
##  Max.   :25.0   Max.   :120.00

GROUP_BY COLOR

ars<-cars%>%mutate(color=ifelse(speed<14,"blue",ifelse(speed>14,"red","black")))%>%group_by(color)%>%count()
ars

SUMMARISE

cars<-cars%>%mutate(color=ifelse(speed<14,"blue",ifelse(speed>14,"red","black")))%>%summarise_at(.vars=vars(speed,dist),.funs = mean)
cars