Question 1
df <- pressure
New_Model_df <- cbind(df, pressure0.5= c(sqrt(df[2])))
names(New_Model_df)[3] = "pressure0.5"
New_Model_df## temperature pressure pressure0.5
## 1 0 0.0002 0.01414214
## 2 20 0.0012 0.03464102
## 3 40 0.0060 0.07745967
## 4 60 0.0300 0.17320508
## 5 80 0.0900 0.30000000
## 6 100 0.2700 0.51961524
## 7 120 0.7500 0.86602540
## 8 140 1.8500 1.36014705
## 9 160 4.2000 2.04939015
## 10 180 8.8000 2.96647939
## 11 200 17.3000 4.15932687
## 12 220 32.1000 5.66568619
## 13 240 57.0000 7.54983444
## 14 260 96.0000 9.79795897
## 15 280 157.0000 12.52996409
## 16 300 247.0000 15.71623365
## 17 320 376.0000 19.39071943
## 18 340 558.0000 23.62202362
## 19 360 806.0000 28.39013913Question 2
x <- c(23,45,-12,NA,52,-54, NA, 22)
x[c(3,6)]<-NA
x## [1] 23 45 NA NA 52 NA NA 22 x[is.na(x)]## [1] NA NA NA NA is.na(x)## [1] FALSE FALSE TRUE TRUE FALSE TRUE TRUE FALSEQuestion 3
mtcars %>% filter(cyl==4)## mpg cyl disp hp drat wt qsec vs am gear carb
## Datsun 710 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1
## Merc 240D 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2
## Merc 230 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2
## Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1
## Honda Civic 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
## Toyota Corolla 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1
## Toyota Corona 21.5 4 120.1 97 3.70 2.465 20.01 1 0 3 1
## Fiat X1-9 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1
## Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
## Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2
## Volvo 142E 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2mtcars %>% filter(mpg>25)## mpg cyl disp hp drat wt qsec vs am gear carb
## Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1
## Honda Civic 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
## Toyota Corolla 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1
## Fiat X1-9 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1
## Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
## Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2mtcars %>% filter(cyl==4 & mpg>25)## mpg cyl disp hp drat wt qsec vs am gear carb
## Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1
## Honda Civic 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2
## Toyota Corolla 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1
## Fiat X1-9 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1
## Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2
## Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2mtcars %>% count(mtcars$cyl)## mtcars$cyl n
## 1 4 11
## 2 6 7
## 3 8 14mtcars %>% count(mtcars$cyl, mean(mpg))## mtcars$cyl mean(mpg) n
## 1 4 20.09062 11
## 2 6 20.09062 7
## 3 8 20.09062 14