#0318連續資料分析
x <- mtcars
x
## mpg cyl disp hp drat wt qsec vs am gear carb
## Mazda RX4 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4
## Mazda RX4 Wag 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4
## Datsun 710 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1
## Hornet 4 Drive 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1
## Hornet Sportabout 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2
## Valiant 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1
## Duster 360 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4
## 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
## Merc 280 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4
## Merc 280C 17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4
## Merc 450SE 16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 3
## Merc 450SL 17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 3
## Merc 450SLC 15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 3
## Cadillac Fleetwood 10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4
## Lincoln Continental 10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4
## Chrysler Imperial 14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4
## 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
## Dodge Challenger 15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2
## AMC Javelin 15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2
## Camaro Z28 13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 4
## Pontiac Firebird 19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2
## 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
## Ford Pantera L 15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 4
## Ferrari Dino 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6
## Maserati Bora 15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 8
## Volvo 142E 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2
summary(x)
## mpg cyl disp hp
## Min. :10.40 Min. :4.000 Min. : 71.1 Min. : 52.0
## 1st Qu.:15.43 1st Qu.:4.000 1st Qu.:120.8 1st Qu.: 96.5
## Median :19.20 Median :6.000 Median :196.3 Median :123.0
## Mean :20.09 Mean :6.188 Mean :230.7 Mean :146.7
## 3rd Qu.:22.80 3rd Qu.:8.000 3rd Qu.:326.0 3rd Qu.:180.0
## Max. :33.90 Max. :8.000 Max. :472.0 Max. :335.0
## drat wt qsec vs
## Min. :2.760 Min. :1.513 Min. :14.50 Min. :0.0000
## 1st Qu.:3.080 1st Qu.:2.581 1st Qu.:16.89 1st Qu.:0.0000
## Median :3.695 Median :3.325 Median :17.71 Median :0.0000
## Mean :3.597 Mean :3.217 Mean :17.85 Mean :0.4375
## 3rd Qu.:3.920 3rd Qu.:3.610 3rd Qu.:18.90 3rd Qu.:1.0000
## Max. :4.930 Max. :5.424 Max. :22.90 Max. :1.0000
## am gear carb
## Min. :0.0000 Min. :3.000 Min. :1.000
## 1st Qu.:0.0000 1st Qu.:3.000 1st Qu.:2.000
## Median :0.0000 Median :4.000 Median :2.000
## Mean :0.4062 Mean :3.688 Mean :2.812
## 3rd Qu.:1.0000 3rd Qu.:4.000 3rd Qu.:4.000
## Max. :1.0000 Max. :5.000 Max. :8.000
str(x)
## 'data.frame': 32 obs. of 11 variables:
## $ mpg : num 21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ...
## $ cyl : num 6 6 4 6 8 6 8 4 4 6 ...
## $ disp: num 160 160 108 258 360 ...
## $ hp : num 110 110 93 110 175 105 245 62 95 123 ...
## $ drat: num 3.9 3.9 3.85 3.08 3.15 2.76 3.21 3.69 3.92 3.92 ...
## $ wt : num 2.62 2.88 2.32 3.21 3.44 ...
## $ qsec: num 16.5 17 18.6 19.4 17 ...
## $ vs : num 0 0 1 1 0 1 0 1 1 1 ...
## $ am : num 1 1 1 0 0 0 0 0 0 0 ...
## $ gear: num 4 4 4 3 3 3 3 4 4 4 ...
## $ carb: num 4 4 1 1 2 1 4 2 2 4 ...
# [, 1] mpg ：Miles/(US) gallon 耗油量
# [, 2] cyl ：Number of cylinders 汽缸數
# [, 3] disp：Displacement (cu.in., cubic inch) 排氣量
# [, 4] hp ：Gross horsepower 馬力
# [, 5] drat：Rear axle ratio 後輪軸減速比
# [, 6] wt ：Weight (1000 lbs) 車體重量
# [, 7] qsec：1/4 mile time 1/4英里加速秒數
# [, 8] vs ：V/S，0代表V型引擎，1代表直立式引擎
# [, 9] am ：Transmission (0 = automatic自排, 1 = manual手排)
# [,10] gear：Number of forward gears 變速箱
# [,11] carb：Number of carburetors化油器
#七、請比較：車體重量(Weight)、馬力(hp)、變速箱(gear)與耗油量(mpg )的關係，並畫圖。
#plot(x, y)畫散佈圖
par(mfrow = c(1,3))#(係數,欄數)
plot(x$wt,x$mpg,col="blue")
plot(x$hp,x$mpg,col="red")
plot(x$gear,x$mpg,col="cyan")
#,用圖形控制函數par(mfrow = c(列數欄數)) 畫多張圖
#離開par()
#用cor(x, y)計算相關係數
cor(x$wt,x$mpg)
## [1] -0.8676594
cor(x$hp,x$mpg)
## [1] -0.7761684
cor(x$gear,x$mpg)
## [1] 0.4802848
#八、請比較：自手排(am)、變速箱(gear)與耗油量(mpg)的關係，並畫圖。
#先分組，再計算
#tapply(被分析的欄位，分組依據欄位，計算函數)
am<-tapply(x$mpg,x$am,mean)
am
## 0 1
## 17.14737 24.39231
gear<-tapply(x$mpg, x$gear, mean)
par(mfrow=c(1,2))
barplot(am)
barplot(gear)
#九、請比較：耗油量(mpg)、馬力(hp)與加速秒數(qsec)的關係，並畫圖。
par(mfrow = c(1,2))#(係數,欄數)
plot(x$mpg,x$qsec,col="blue",main ="mpg/qsec",sub="By Willy" )
plot(x$hp,x$qsec,col="red",main ="hp/qsec",sub="By Willy" )
cor(x$mpg,x$qsec)
## [1] 0.418684
cor(x$hp,x$qsec)
## [1] -0.7082234
#十、請比較：汽缸數(cyl)、變速箱(gear)與加速秒數(qsec)的關係，並畫圖。
cyl<-tapply(x$qsec,x$cyl,mean)
cyl
## 4 6 8
## 19.13727 17.97714 16.77214
gear<-tapply(x$qsec, x$gear, mean)
gear
## 3 4 5
## 17.692 18.965 15.640
par(mfrow=c(1,2))
barplot(cyl,col=c(11,30,28),main="Cyl/Average qsec",sub="By Willy",ylab="qsec",xlab="cyl")
barplot(gear,col=c(11,30,28),main="Gear/Average qsec",sub="By Willy",ylab="qsec",xlab="gear")
