数据统计分析的第一步就是对数据的描述性统计，R语言令人头疼的是，提供这项服务的实在太多了
1 > data("mtcars") 2 > force(mtcars) 3 mpg cyl disp hp drat wt qsec vs am gear carb 4 Mazda RX4 21.0 6 160.0 110 3.90 2.620 16.46 0 1 4 4 5 Mazda RX4 Wag 21.0 6 160.0 110 3.90 2.875 17.02 0 1 4 4 6 Datsun 710 22.8 4 108.0 93 3.85 2.320 18.61 1 1 4 1 7 Hornet 4 Drive 21.4 6 258.0 110 3.08 3.215 19.44 1 0 3 1 8 Hornet Sportabout 18.7 8 360.0 175 3.15 3.440 17.02 0 0 3 2 9 Valiant 18.1 6 225.0 105 2.76 3.460 20.22 1 0 3 1 10 Duster 360 14.3 8 360.0 245 3.21 3.570 15.84 0 0 3 4 11 Merc 240D 24.4 4 146.7 62 3.69 3.190 20.00 1 0 4 2 12 Merc 230 22.8 4 140.8 95 3.92 3.150 22.90 1 0 4 2 13 Merc 280 19.2 6 167.6 123 3.92 3.440 18.30 1 0 4 4 14 Merc 280C 17.8 6 167.6 123 3.92 3.440 18.90 1 0 4 4 15 Merc 450SE 16.4 8 275.8 180 3.07 4.070 17.40 0 0 3 3 16 Merc 450SL 17.3 8 275.8 180 3.07 3.730 17.60 0 0 3 3 17 Merc 450SLC 15.2 8 275.8 180 3.07 3.780 18.00 0 0 3 3 18 Cadillac Fleetwood 10.4 8 472.0 205 2.93 5.250 17.98 0 0 3 4 19 Lincoln Continental 10.4 8 460.0 215 3.00 5.424 17.82 0 0 3 4 20 Chrysler Imperial 14.7 8 440.0 230 3.23 5.345 17.42 0 0 3 4 21 Fiat 128 32.4 4 78.7 66 4.08 2.200 19.47 1 1 4 1 22 Honda Civic 30.4 4 75.7 52 4.93 1.615 18.52 1 1 4 2 23 Toyota Corolla 33.9 4 71.1 65 4.22 1.835 19.90 1 1 4 1 24 Toyota Corona 21.5 4 120.1 97 3.70 2.465 20.01 1 0 3 1 25 Dodge Challenger 15.5 8 318.0 150 2.76 3.520 16.87 0 0 3 2 26 AMC Javelin 15.2 8 304.0 150 3.15 3.435 17.30 0 0 3 2 27 Camaro Z28 13.3 8 350.0 245 3.73 3.840 15.41 0 0 3 4 28 Pontiac Firebird 19.2 8 400.0 175 3.08 3.845 17.05 0 0 3 2 29 Fiat X1-9 27.3 4 79.0 66 4.08 1.935 18.90 1 1 4 1 30 Porsche 914-2 26.0 4 120.3 91 4.43 2.140 16.70 0 1 5 2 31 Lotus Europa 30.4 4 95.1 113 3.77 1.513 16.90 1 1 5 2 32 Ford Pantera L 15.8 8 351.0 264 4.22 3.170 14.50 0 1 5 4 33 Ferrari Dino 19.7 6 145.0 175 3.62 2.770 15.50 0 1 5 6 34 Maserati Bora 15.0 8 301.0 335 3.54 3.570 14.60 0 1 5 8 35 Volvo 142E 21.4 4 121.0 109 4.11 2.780 18.60 1 1 4 2 36 > summary(mtcars) 37 mpg cyl disp hp 38 Min. :10.40 Min. :4.000 Min. : 71.1 Min. : 52.0 39 1st Qu.:15.43 1st Qu.:4.000 1st Qu.:120.8 1st Qu.: 96.5 40 Median :19.20 Median :6.000 Median :196.3 Median :123.0 41 Mean :20.09 Mean :6.188 Mean :230.7 Mean :146.7 42 3rd Qu.:22.80 3rd Qu.:8.000 3rd Qu.:326.0 3rd Qu.:180.0 43 Max. :33.90 Max. :8.000 Max. :472.0 Max. :335.0 44 drat wt qsec vs 45 Min. :2.760 Min. :1.513 Min. :14.50 Min. :0.0000 46 1st Qu.:3.080 1st Qu.:2.581 1st Qu.:16.89 1st Qu.:0.0000 47 Median :3.695 Median :3.325 Median :17.71 Median :0.0000 48 Mean :3.597 Mean :3.217 Mean :17.85 Mean :0.4375 49 3rd Qu.:3.920 3rd Qu.:3.610 3rd Qu.:18.90 3rd Qu.:1.0000 50 Max. :4.930 Max. :5.424 Max. :22.90 Max. :1.0000 51 am gear carb 52 Min. :0.0000 Min. :3.000 Min. :1.000 53 1st Qu.:0.0000 1st Qu.:3.000 1st Qu.:2.000 54 Median :0.0000 Median :4.000 Median :2.000 55 Mean :0.4062 Mean :3.688 Mean :2.812 56 3rd Qu.:1.0000 3rd Qu.:4.000 3rd Qu.:4.000 57 Max. :1.0000 Max. :5.000 Max. :8.000
R语言的基本包里面自带mtcars数据集，不要到处找了
直接data(mtcars)引用即可
重点关注summary函数
对于数值类型数据，给出了最小值、最小四分之一、中间值、均值、最大四分之一、最大值
对于名义型数据，对不起，summary表示不懂
1 summary(a) 2 Length Class Mode 3 4 character character 4 > c(T,T,F,T,T,F,T,T,F,T,T,F,T,T,F)->b 5 > summary(b) 6 Mode FALSE TRUE 7 logical 5 10
对于逻辑数据，统计T、F的数量
PS：summary是一个基本函数，提供对object的描述，object，你懂的，一旦你搞不拎清哪个对象，summary它，我的理解就像是调‘object’的档案差不多
1 > l<-list(mtcars,a,b) 2 > summary(l) 3 Length Class Mode 4 [1,] 11 data.frame list 5 [2,] 4 -none- character 6 [3,] 15 -none- logical
这次summary了一个list，可以观察的到，summary仅仅对list对象的元素进行了统计，如果想继续挖掘呢？
1 > summary(l[[1]]) 2 mpg cyl disp hp 3 Min. :10.40 Min. :4.000 Min. : 71.1 Min. : 52.0 4 1st Qu.:15.43 1st Qu.:4.000 1st Qu.:120.8 1st Qu.: 96.5 5 Median :19.20 Median :6.000 Median :196.3 Median :123.0 6 Mean :20.09 Mean :6.188 Mean :230.7 Mean :146.7 7 3rd Qu.:22.80 3rd Qu.:8.000 3rd Qu.:326.0 3rd Qu.:180.0 8 Max. :33.90 Max. :8.000 Max. :472.0 Max. :335.0 9 drat wt qsec vs 10 Min. :2.760 Min. :1.513 Min. :14.50 Min. :0.0000 11 1st Qu.:3.080 1st Qu.:2.581 1st Qu.:16.89 1st Qu.:0.0000 12 Median :3.695 Median :3.325 Median :17.71 Median :0.0000 13 Mean :3.597 Mean :3.217 Mean :17.85 Mean :0.4375 14 3rd Qu.:3.920 3rd Qu.:3.610 3rd Qu.:18.90 3rd Qu.:1.0000 15 Max. :4.930 Max. :5.424 Max. :22.90 Max. :1.0000 16 am gear carb 17 Min. :0.0000 Min. :3.000 Min. :1.000 18 1st Qu.:0.0000 1st Qu.:3.000 1st Qu.:2.000 19 Median :0.0000 Median :4.000 Median :2.000 20 Mean :0.4062 Mean :3.688 Mean :2.812 21 3rd Qu.:1.0000 3rd Qu.:4.000 3rd Qu.:4.000 22 Max. :1.0000 Max. :5.000 Max. :8.000 23 > summary(l[[2]]) 24 Length Class Mode 25 4 character character 26 >