R语言实战-统计分析基础-描述性统计1-summary

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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、summary函数

 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 >