20 Огляд набору даних

Автор

Юрій Клебан

20.1 Завантаження даних

Для прикладів використання базових функцій скористаємося набором даних mtcars, що присутній у пакеті base.

Детальну інформацію про нього можна знайти нижче:

?mtcars

mtcars {datasets}

R Documentation

Motor Trend Car Road Tests

Description

The data was extracted from the 1974 Motor Trend US magazine, and comprises fuel consumption and 10 aspects of automobile design and performance for 32 automobiles (1973–74 models).

Usage

mtcars

Format

A data frame with 32 observations on 11 (numeric) variables.

[, 1]	mpg	Miles/(US) gallon
[, 2]	cyl	Number of cylinders
[, 3]	disp	Displacement (cu.in.)
[, 4]	hp	Gross horsepower
[, 5]	drat	Rear axle ratio
[, 6]	wt	Weight (1000 lbs)
[, 7]	qsec	1/4 mile time
[, 8]	vs	Engine (0 = V-shaped, 1 = straight)
[, 9]	am	Transmission (0 = automatic, 1 = manual)
[,10]	gear	Number of forward gears
[,11]	carb	Number of carburetors

Note

Henderson and Velleman (1981) comment in a footnote to Table 1: ‘Hocking [original transcriber]'s noncrucial coding of the Mazda's rotary engine as a straight six-cylinder engine and the Porsche's flat engine as a V engine, as well as the inclusion of the diesel Mercedes 240D, have been retained to enable direct comparisons to be made with previous analyses.’

Source

Henderson and Velleman (1981), Building multiple regression models interactively. Biometrics, 37, 391–411.

Examples

require(graphics)
pairs(mtcars, main = "mtcars data", gap = 1/4)
coplot(mpg ~ disp | as.factor(cyl), data = mtcars,
       panel = panel.smooth, rows = 1)
## possibly more meaningful, e.g., for summary() or bivariate plots:
mtcars2 <- within(mtcars, {
   vs <- factor(vs, labels = c("V", "S"))
   am <- factor(am, labels = c("automatic", "manual"))
   cyl  <- ordered(cyl)
   gear <- ordered(gear)
   carb <- ordered(carb)
})
summary(mtcars2)

[Package datasets version 4.1.3 ]

20.2 Перегляд інформації

Функція head() показує N перших записів у наборі даних (за замовчуванням їх 6).

head(mtcars)

A data.frame: 6 × 11
	mpg	cyl	disp	hp	drat	wt	qsec	vs	am	gear	carb
	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>
Mazda RX4	21.0	6	160	110	3.90	2.620	16.46	0	1	4	4
Mazda RX4 Wag	21.0	6	160	110	3.90	2.875	17.02	0	1	4	4
Datsun 710	22.8	4	108	93	3.85	2.320	18.61	1	1	4	1
Hornet 4 Drive	21.4	6	258	110	3.08	3.215	19.44	1	0	3	1
Hornet Sportabout	18.7	8	360	175	3.15	3.440	17.02	0	0	3	2
Valiant	18.1	6	225	105	2.76	3.460	20.22	1	0	3	1

head(mtcars, 10)

A data.frame: 10 × 11
	mpg	cyl	disp	hp	drat	wt	qsec	vs	am	gear	carb
	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>
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

Якщо ж ми бажаємо переглянути N елементів з кінця набору даних, то варто скористатися tail():

tail(mtcars, 7)

A data.frame: 7 × 11
	mpg	cyl	disp	hp	drat	wt	qsec	vs	am	gear	carb
	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>
Fiat X1-9	27.3	4	79.0	66	4.08	1.935	18.9	1	1	4	1
Porsche 914-2	26.0	4	120.3	91	4.43	2.140	16.7	0	1	5	2
Lotus Europa	30.4	4	95.1	113	3.77	1.513	16.9	1	1	5	2
Ford Pantera L	15.8	8	351.0	264	4.22	3.170	14.5	0	1	5	4
Ferrari Dino	19.7	6	145.0	175	3.62	2.770	15.5	0	1	5	6
Maserati Bora	15.0	8	301.0	335	3.54	3.570	14.6	0	1	5	8
Volvo 142E	21.4	4	121.0	109	4.11	2.780	18.6	1	1	4	2

20.3 Назви параметрів

Для перегляду списку наяавних показників у наборі даних можна скористатися names():

names(mtcars)

'mpg'
'cyl'
'disp'
'hp'
'drat'
'wt'
'qsec'
'vs'
'am'
'gear'
'carb'

20.3.1 Розмірність набору даних

Кількість рядків:

dim(mtcars)

Кількість рядків окремо:

nrow(mtcars)

Кількість стовпців:

ncol(mtcars)

20.4 Структура даних та описова статистика

Структура даних містить інформацію про тип набору даних, його розмірність, перелік стовпців та їх типи даних:

str(mtcars)

'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 ...

Базова описова статистика може бути переглянута за допомогою функції summary():

summary(mtcars)

      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

20.5 Інші методи

library(psych)
describe(mtcars)

A psych: 11 × 13
	vars	n	mean	sd	median	trimmed	mad	min	max	range	skew	kurtosis	se
	<int>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>
mpg	1	32	20.090625	6.0269481	19.200	19.6961538	5.4114900	10.400	33.900	23.500	0.6106550	-0.37276603	1.06542396
cyl	2	32	6.187500	1.7859216	6.000	6.2307692	2.9652000	4.000	8.000	4.000	-0.1746119	-1.76211977	0.31570933
disp	3	32	230.721875	123.9386938	196.300	222.5230769	140.4763500	71.100	472.000	400.900	0.3816570	-1.20721195	21.90947271
hp	4	32	146.687500	68.5628685	123.000	141.1923077	77.0952000	52.000	335.000	283.000	0.7260237	-0.13555112	12.12031731
drat	5	32	3.596563	0.5346787	3.695	3.5792308	0.7042350	2.760	4.930	2.170	0.2659039	-0.71470062	0.09451874
wt	6	32	3.217250	0.9784574	3.325	3.1526923	0.7672455	1.513	5.424	3.911	0.4231465	-0.02271075	0.17296847
qsec	7	32	17.848750	1.7869432	17.710	17.8276923	1.4158830	14.500	22.900	8.400	0.3690453	0.33511422	0.31588992
vs	8	32	0.437500	0.5040161	0.000	0.4230769	0.0000000	0.000	1.000	1.000	0.2402577	-2.00193762	0.08909831
am	9	32	0.406250	0.4989909	0.000	0.3846154	0.0000000	0.000	1.000	1.000	0.3640159	-1.92474143	0.08820997
gear	10	32	3.687500	0.7378041	4.000	3.6153846	1.4826000	3.000	5.000	2.000	0.5288545	-1.06975068	0.13042656
carb	11	32	2.812500	1.6152000	2.000	2.6538462	1.4826000	1.000	8.000	7.000	1.0508738	1.25704307	0.28552971

describe(
          mtcars, 
          fast = TRUE, 
          quant = c(0.25, 0.50, 0.75), 
          ranges = FALSE, 
)

A psych: 11 × 8
	vars	n	mean	sd	se	Q0.25	Q0.5	Q0.75
	<int>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>	<dbl>
mpg	1	32	20.090625	6.0269481	1.06542396	15.42500	19.200	22.80
cyl	2	32	6.187500	1.7859216	0.31570933	4.00000	6.000	8.00
disp	3	32	230.721875	123.9386938	21.90947271	120.82500	196.300	326.00
hp	4	32	146.687500	68.5628685	12.12031731	96.50000	123.000	180.00
drat	5	32	3.596563	0.5346787	0.09451874	3.08000	3.695	3.92
wt	6	32	3.217250	0.9784574	0.17296847	2.58125	3.325	3.61
qsec	7	32	17.848750	1.7869432	0.31588992	16.89250	17.710	18.90
vs	8	32	0.437500	0.5040161	0.08909831	0.00000	0.000	1.00
am	9	32	0.406250	0.4989909	0.08820997	0.00000	0.000	1.00
gear	10	32	3.687500	0.7378041	0.13042656	3.00000	4.000	4.00
carb	11	32	2.812500	1.6152000	0.28552971	2.00000	2.000	4.00

20.5.1 Описова статистика для групи

describe(
          mtcars ~ mpg,
          fast = TRUE, 
          quant = c(0.25, 0.50, 0.75), 
          ranges = FALSE, omit = TRUE
)


 Descriptive statistics by group 
group: 10.4
     vars n   mean   sd   se  Q0.25   Q0.5  Q0.75
mpg     1 2  10.40 0.00 0.00  10.40  10.40  10.40
cyl     2 2   8.00 0.00 0.00   8.00   8.00   8.00
disp    3 2 466.00 8.49 6.00 463.00 466.00 469.00
hp      4 2 210.00 7.07 5.00 207.50 210.00 212.50
drat    5 2   2.96 0.05 0.03   2.95   2.96   2.98
wt      6 2   5.34 0.12 0.09   5.29   5.34   5.38
qsec    7 2  17.90 0.11 0.08  17.86  17.90  17.94
vs      8 2   0.00 0.00 0.00   0.00   0.00   0.00
am      9 2   0.00 0.00 0.00   0.00   0.00   0.00
gear   10 2   3.00 0.00 0.00   3.00   3.00   3.00
carb   11 2   4.00 0.00 0.00   4.00   4.00   4.00
------------------------------------------------------------ 
group: 13.3
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  13.30 NA NA  13.30  13.30  13.30
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 350.00 NA NA 350.00 350.00 350.00
hp      4 1 245.00 NA NA 245.00 245.00 245.00
drat    5 1   3.73 NA NA   3.73   3.73   3.73
wt      6 1   3.84 NA NA   3.84   3.84   3.84
qsec    7 1  15.41 NA NA  15.41  15.41  15.41
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   4.00 NA NA   4.00   4.00   4.00
------------------------------------------------------------ 
group: 14.3
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  14.30 NA NA  14.30  14.30  14.30
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 360.00 NA NA 360.00 360.00 360.00
hp      4 1 245.00 NA NA 245.00 245.00 245.00
drat    5 1   3.21 NA NA   3.21   3.21   3.21
wt      6 1   3.57 NA NA   3.57   3.57   3.57
qsec    7 1  15.84 NA NA  15.84  15.84  15.84
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   4.00 NA NA   4.00   4.00   4.00
------------------------------------------------------------ 
group: 14.7
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  14.70 NA NA  14.70  14.70  14.70
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 440.00 NA NA 440.00 440.00 440.00
hp      4 1 230.00 NA NA 230.00 230.00 230.00
drat    5 1   3.23 NA NA   3.23   3.23   3.23
wt      6 1   5.34 NA NA   5.34   5.34   5.34
qsec    7 1  17.42 NA NA  17.42  17.42  17.42
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   4.00 NA NA   4.00   4.00   4.00
------------------------------------------------------------ 
group: 15
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  15.00 NA NA  15.00  15.00  15.00
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 301.00 NA NA 301.00 301.00 301.00
hp      4 1 335.00 NA NA 335.00 335.00 335.00
drat    5 1   3.54 NA NA   3.54   3.54   3.54
wt      6 1   3.57 NA NA   3.57   3.57   3.57
qsec    7 1  14.60 NA NA  14.60  14.60  14.60
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   1.00 NA NA   1.00   1.00   1.00
gear   10 1   5.00 NA NA   5.00   5.00   5.00
carb   11 1   8.00 NA NA   8.00   8.00   8.00
------------------------------------------------------------ 
group: 15.2
     vars n   mean    sd    se  Q0.25   Q0.5  Q0.75
mpg     1 2  15.20  0.00  0.00  15.20  15.20  15.20
cyl     2 2   8.00  0.00  0.00   8.00   8.00   8.00
disp    3 2 289.90 19.94 14.10 282.85 289.90 296.95
hp      4 2 165.00 21.21 15.00 157.50 165.00 172.50
drat    5 2   3.11  0.06  0.04   3.09   3.11   3.13
wt      6 2   3.61  0.24  0.17   3.52   3.61   3.69
qsec    7 2  17.65  0.49  0.35  17.48  17.65  17.82
vs      8 2   0.00  0.00  0.00   0.00   0.00   0.00
am      9 2   0.00  0.00  0.00   0.00   0.00   0.00
gear   10 2   3.00  0.00  0.00   3.00   3.00   3.00
carb   11 2   2.50  0.71  0.50   2.25   2.50   2.75
------------------------------------------------------------ 
group: 15.5
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  15.50 NA NA  15.50  15.50  15.50
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 318.00 NA NA 318.00 318.00 318.00
hp      4 1 150.00 NA NA 150.00 150.00 150.00
drat    5 1   2.76 NA NA   2.76   2.76   2.76
wt      6 1   3.52 NA NA   3.52   3.52   3.52
qsec    7 1  16.87 NA NA  16.87  16.87  16.87
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   2.00 NA NA   2.00   2.00   2.00
------------------------------------------------------------ 
group: 15.8
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  15.80 NA NA  15.80  15.80  15.80
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 351.00 NA NA 351.00 351.00 351.00
hp      4 1 264.00 NA NA 264.00 264.00 264.00
drat    5 1   4.22 NA NA   4.22   4.22   4.22
wt      6 1   3.17 NA NA   3.17   3.17   3.17
qsec    7 1  14.50 NA NA  14.50  14.50  14.50
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   1.00 NA NA   1.00   1.00   1.00
gear   10 1   5.00 NA NA   5.00   5.00   5.00
carb   11 1   4.00 NA NA   4.00   4.00   4.00
------------------------------------------------------------ 
group: 16.4
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  16.40 NA NA  16.40  16.40  16.40
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 275.80 NA NA 275.80 275.80 275.80
hp      4 1 180.00 NA NA 180.00 180.00 180.00
drat    5 1   3.07 NA NA   3.07   3.07   3.07
wt      6 1   4.07 NA NA   4.07   4.07   4.07
qsec    7 1  17.40 NA NA  17.40  17.40  17.40
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   3.00 NA NA   3.00   3.00   3.00
------------------------------------------------------------ 
group: 17.3
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  17.30 NA NA  17.30  17.30  17.30
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 275.80 NA NA 275.80 275.80 275.80
hp      4 1 180.00 NA NA 180.00 180.00 180.00
drat    5 1   3.07 NA NA   3.07   3.07   3.07
wt      6 1   3.73 NA NA   3.73   3.73   3.73
qsec    7 1  17.60 NA NA  17.60  17.60  17.60
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   3.00 NA NA   3.00   3.00   3.00
------------------------------------------------------------ 
group: 17.8
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  17.80 NA NA  17.80  17.80  17.80
cyl     2 1   6.00 NA NA   6.00   6.00   6.00
disp    3 1 167.60 NA NA 167.60 167.60 167.60
hp      4 1 123.00 NA NA 123.00 123.00 123.00
drat    5 1   3.92 NA NA   3.92   3.92   3.92
wt      6 1   3.44 NA NA   3.44   3.44   3.44
qsec    7 1  18.90 NA NA  18.90  18.90  18.90
vs      8 1   1.00 NA NA   1.00   1.00   1.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   4.00 NA NA   4.00   4.00   4.00
carb   11 1   4.00 NA NA   4.00   4.00   4.00
------------------------------------------------------------ 
group: 18.1
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  18.10 NA NA  18.10  18.10  18.10
cyl     2 1   6.00 NA NA   6.00   6.00   6.00
disp    3 1 225.00 NA NA 225.00 225.00 225.00
hp      4 1 105.00 NA NA 105.00 105.00 105.00
drat    5 1   2.76 NA NA   2.76   2.76   2.76
wt      6 1   3.46 NA NA   3.46   3.46   3.46
qsec    7 1  20.22 NA NA  20.22  20.22  20.22
vs      8 1   1.00 NA NA   1.00   1.00   1.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   1.00 NA NA   1.00   1.00   1.00
------------------------------------------------------------ 
group: 18.7
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  18.70 NA NA  18.70  18.70  18.70
cyl     2 1   8.00 NA NA   8.00   8.00   8.00
disp    3 1 360.00 NA NA 360.00 360.00 360.00
hp      4 1 175.00 NA NA 175.00 175.00 175.00
drat    5 1   3.15 NA NA   3.15   3.15   3.15
wt      6 1   3.44 NA NA   3.44   3.44   3.44
qsec    7 1  17.02 NA NA  17.02  17.02  17.02
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   2.00 NA NA   2.00   2.00   2.00
------------------------------------------------------------ 
group: 19.2
     vars n   mean     sd     se  Q0.25   Q0.5  Q0.75
mpg     1 2  19.20   0.00   0.00  19.20  19.20  19.20
cyl     2 2   7.00   1.41   1.00   6.50   7.00   7.50
disp    3 2 283.80 164.33 116.20 225.70 283.80 341.90
hp      4 2 149.00  36.77  26.00 136.00 149.00 162.00
drat    5 2   3.50   0.59   0.42   3.29   3.50   3.71
wt      6 2   3.64   0.29   0.20   3.54   3.64   3.74
qsec    7 2  17.68   0.88   0.62  17.36  17.68  17.99
vs      8 2   0.50   0.71   0.50   0.25   0.50   0.75
am      9 2   0.00   0.00   0.00   0.00   0.00   0.00
gear   10 2   3.50   0.71   0.50   3.25   3.50   3.75
carb   11 2   3.00   1.41   1.00   2.50   3.00   3.50
------------------------------------------------------------ 
group: 19.7
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  19.70 NA NA  19.70  19.70  19.70
cyl     2 1   6.00 NA NA   6.00   6.00   6.00
disp    3 1 145.00 NA NA 145.00 145.00 145.00
hp      4 1 175.00 NA NA 175.00 175.00 175.00
drat    5 1   3.62 NA NA   3.62   3.62   3.62
wt      6 1   2.77 NA NA   2.77   2.77   2.77
qsec    7 1  15.50 NA NA  15.50  15.50  15.50
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   1.00 NA NA   1.00   1.00   1.00
gear   10 1   5.00 NA NA   5.00   5.00   5.00
carb   11 1   6.00 NA NA   6.00   6.00   6.00
------------------------------------------------------------ 
group: 21
     vars n   mean   sd   se  Q0.25   Q0.5  Q0.75
mpg     1 2  21.00 0.00 0.00  21.00  21.00  21.00
cyl     2 2   6.00 0.00 0.00   6.00   6.00   6.00
disp    3 2 160.00 0.00 0.00 160.00 160.00 160.00
hp      4 2 110.00 0.00 0.00 110.00 110.00 110.00
drat    5 2   3.90 0.00 0.00   3.90   3.90   3.90
wt      6 2   2.75 0.18 0.13   2.68   2.75   2.81
qsec    7 2  16.74 0.40 0.28  16.60  16.74  16.88
vs      8 2   0.00 0.00 0.00   0.00   0.00   0.00
am      9 2   1.00 0.00 0.00   1.00   1.00   1.00
gear   10 2   4.00 0.00 0.00   4.00   4.00   4.00
carb   11 2   4.00 0.00 0.00   4.00   4.00   4.00
------------------------------------------------------------ 
group: 21.4
     vars n   mean    sd    se  Q0.25   Q0.5  Q0.75
mpg     1 2  21.40  0.00  0.00  21.40  21.40  21.40
cyl     2 2   5.00  1.41  1.00   4.50   5.00   5.50
disp    3 2 189.50 96.87 68.50 155.25 189.50 223.75
hp      4 2 109.50  0.71  0.50 109.25 109.50 109.75
drat    5 2   3.60  0.73  0.52   3.34   3.60   3.85
wt      6 2   3.00  0.31  0.22   2.89   3.00   3.11
qsec    7 2  19.02  0.59  0.42  18.81  19.02  19.23
vs      8 2   1.00  0.00  0.00   1.00   1.00   1.00
am      9 2   0.50  0.71  0.50   0.25   0.50   0.75
gear   10 2   3.50  0.71  0.50   3.25   3.50   3.75
carb   11 2   1.50  0.71  0.50   1.25   1.50   1.75
------------------------------------------------------------ 
group: 21.5
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  21.50 NA NA  21.50  21.50  21.50
cyl     2 1   4.00 NA NA   4.00   4.00   4.00
disp    3 1 120.10 NA NA 120.10 120.10 120.10
hp      4 1  97.00 NA NA  97.00  97.00  97.00
drat    5 1   3.70 NA NA   3.70   3.70   3.70
wt      6 1   2.46 NA NA   2.46   2.46   2.46
qsec    7 1  20.01 NA NA  20.01  20.01  20.01
vs      8 1   1.00 NA NA   1.00   1.00   1.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   3.00 NA NA   3.00   3.00   3.00
carb   11 1   1.00 NA NA   1.00   1.00   1.00
------------------------------------------------------------ 
group: 22.8
     vars n   mean    sd    se  Q0.25   Q0.5  Q0.75
mpg     1 2  22.80  0.00  0.00  22.80  22.80  22.80
cyl     2 2   4.00  0.00  0.00   4.00   4.00   4.00
disp    3 2 124.40 23.19 16.40 116.20 124.40 132.60
hp      4 2  94.00  1.41  1.00  93.50  94.00  94.50
drat    5 2   3.88  0.05  0.03   3.87   3.88   3.90
wt      6 2   2.73  0.59  0.42   2.53   2.73   2.94
qsec    7 2  20.75  3.03  2.14  19.68  20.75  21.83
vs      8 2   1.00  0.00  0.00   1.00   1.00   1.00
am      9 2   0.50  0.71  0.50   0.25   0.50   0.75
gear   10 2   4.00  0.00  0.00   4.00   4.00   4.00
carb   11 2   1.50  0.71  0.50   1.25   1.50   1.75
------------------------------------------------------------ 
group: 24.4
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  24.40 NA NA  24.40  24.40  24.40
cyl     2 1   4.00 NA NA   4.00   4.00   4.00
disp    3 1 146.70 NA NA 146.70 146.70 146.70
hp      4 1  62.00 NA NA  62.00  62.00  62.00
drat    5 1   3.69 NA NA   3.69   3.69   3.69
wt      6 1   3.19 NA NA   3.19   3.19   3.19
qsec    7 1  20.00 NA NA  20.00  20.00  20.00
vs      8 1   1.00 NA NA   1.00   1.00   1.00
am      9 1   0.00 NA NA   0.00   0.00   0.00
gear   10 1   4.00 NA NA   4.00   4.00   4.00
carb   11 1   2.00 NA NA   2.00   2.00   2.00
------------------------------------------------------------ 
group: 26
     vars n   mean sd se  Q0.25   Q0.5  Q0.75
mpg     1 1  26.00 NA NA  26.00  26.00  26.00
cyl     2 1   4.00 NA NA   4.00   4.00   4.00
disp    3 1 120.30 NA NA 120.30 120.30 120.30
hp      4 1  91.00 NA NA  91.00  91.00  91.00
drat    5 1   4.43 NA NA   4.43   4.43   4.43
wt      6 1   2.14 NA NA   2.14   2.14   2.14
qsec    7 1  16.70 NA NA  16.70  16.70  16.70
vs      8 1   0.00 NA NA   0.00   0.00   0.00
am      9 1   1.00 NA NA   1.00   1.00   1.00
gear   10 1   5.00 NA NA   5.00   5.00   5.00
carb   11 1   2.00 NA NA   2.00   2.00   2.00
------------------------------------------------------------ 
group: 27.3
     vars n  mean sd se Q0.25  Q0.5 Q0.75
mpg     1 1 27.30 NA NA 27.30 27.30 27.30
cyl     2 1  4.00 NA NA  4.00  4.00  4.00
disp    3 1 79.00 NA NA 79.00 79.00 79.00
hp      4 1 66.00 NA NA 66.00 66.00 66.00
drat    5 1  4.08 NA NA  4.08  4.08  4.08
wt      6 1  1.94 NA NA  1.94  1.94  1.94
qsec    7 1 18.90 NA NA 18.90 18.90 18.90
vs      8 1  1.00 NA NA  1.00  1.00  1.00
am      9 1  1.00 NA NA  1.00  1.00  1.00
gear   10 1  4.00 NA NA  4.00  4.00  4.00
carb   11 1  1.00 NA NA  1.00  1.00  1.00
------------------------------------------------------------ 
group: 30.4
     vars n  mean    sd    se Q0.25  Q0.5 Q0.75
mpg     1 2 30.40  0.00  0.00 30.40 30.40 30.40
cyl     2 2  4.00  0.00  0.00  4.00  4.00  4.00
disp    3 2 85.40 13.72  9.70 80.55 85.40 90.25
hp      4 2 82.50 43.13 30.50 67.25 82.50 97.75
drat    5 2  4.35  0.82  0.58  4.06  4.35  4.64
wt      6 2  1.56  0.07  0.05  1.54  1.56  1.59
qsec    7 2 17.71  1.15  0.81 17.30 17.71 18.12
vs      8 2  1.00  0.00  0.00  1.00  1.00  1.00
am      9 2  1.00  0.00  0.00  1.00  1.00  1.00
gear   10 2  4.50  0.71  0.50  4.25  4.50  4.75
carb   11 2  2.00  0.00  0.00  2.00  2.00  2.00
------------------------------------------------------------ 
group: 32.4
     vars n  mean sd se Q0.25  Q0.5 Q0.75
mpg     1 1 32.40 NA NA 32.40 32.40 32.40
cyl     2 1  4.00 NA NA  4.00  4.00  4.00
disp    3 1 78.70 NA NA 78.70 78.70 78.70
hp      4 1 66.00 NA NA 66.00 66.00 66.00
drat    5 1  4.08 NA NA  4.08  4.08  4.08
wt      6 1  2.20 NA NA  2.20  2.20  2.20
qsec    7 1 19.47 NA NA 19.47 19.47 19.47
vs      8 1  1.00 NA NA  1.00  1.00  1.00
am      9 1  1.00 NA NA  1.00  1.00  1.00
gear   10 1  4.00 NA NA  4.00  4.00  4.00
carb   11 1  1.00 NA NA  1.00  1.00  1.00
------------------------------------------------------------ 
group: 33.9
     vars n  mean sd se Q0.25  Q0.5 Q0.75
mpg     1 1 33.90 NA NA 33.90 33.90 33.90
cyl     2 1  4.00 NA NA  4.00  4.00  4.00
disp    3 1 71.10 NA NA 71.10 71.10 71.10
hp      4 1 65.00 NA NA 65.00 65.00 65.00
drat    5 1  4.22 NA NA  4.22  4.22  4.22
wt      6 1  1.83 NA NA  1.83  1.83  1.83
qsec    7 1 19.90 NA NA 19.90 19.90 19.90
vs      8 1  1.00 NA NA  1.00  1.00  1.00
am      9 1  1.00 NA NA  1.00  1.00  1.00
gear   10 1  4.00 NA NA  4.00  4.00  4.00
carb   11 1  1.00 NA NA  1.00  1.00  1.00

References

https://statisticsglobe.com/data-exploration-r