R ma’lumotlar to‘plami

Ma’lumotlar to‘plami

Ma’lumotlar to‘plami — ko‘pincha jadval ko‘rinishida taqdim etiladigan ma’lumotlar majmuasi.

R’da "mtcars" (Motor Trend Car Road Tests) deb nomlangan mashhur o‘rnatilgan ma’lumotlar to‘plami mavjud bo‘lib, u AQShning 1974-yilgi Motor Trend jurnalidan olingan.

Quyidagi misollarda (va keyingi boblarda) statistik maqsadlarda mtcars ma’lumotlar to‘plamidan foydalanamiz:

Misol

# Print the mtcars data set mtcars

Natija:

                     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

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Ma’lumotlar to‘plami haqida ma’lumot

mtcars ma’lumotlar to‘plami haqida ma’lumot olish uchun so‘roq belgisidan (?) foydalanishingiz mumkin:

Misol

# Use the question mark to get information about the data set ?mtcars

Natija:

mtcars {datasets}

R hujjatlari

Motor Trend Car Road Tests

Tavsif

Ma’lumotlar AQShning 1974-yilgi Motor Trend jurnalidan olingan bo‘lib, 32 ta avtomobil (1973–74-yillar modellari) uchun yoqilg‘i sarfi hamda avtomobil konstruksiyasi va ish ko‘rsatkichlarining 10 ta jihatini o‘z ichiga oladi.

Foydalanish

mtcars

Format

11 ta (sonli) o‘zgaruvchi bo‘yicha 32 ta kuzatuvdan iborat data frame.

[, 1]	mpg	Mil/(AQSH) gallon
[, 2]	cyl	Silindrlar soni
[, 3]	disp	Dvigatel hajmi (kub dyuym)
[, 4]	hp	Umumiy ot kuchi
[, 5]	drat	Orqa o‘q uzatish nisbati
[, 6]	wt	Og‘irlik (1000 funt)
[, 7]	qsec	1/4 mil masofani bosib o‘tish vaqti
[, 8]	vs	Dvigatel (0 = V shaklidagi, 1 = qatorli)
[, 9]	am	Uzatmalar qutisi (0 = avtomatik, 1 = mexanik)
[,10]	gear	Oldinga yurish uzatmalari soni
[,11]	carb	Karbyuratorlar soni

Eslatma

Henderson va Velleman (1981) 1-jadvalga yozilgan izohda shunday deydi: “Hocking [asl ma’lumotlarni ko‘chirib yozgan shaxs] tomonidan Mazda’ning rotorli dvigateli qatorli olti silindrli dvigatel, Porsche’ning oppozit dvigateli esa V shaklidagi dvigatel sifatida unchalik muhim bo‘lmagan tarzda kodlangani, shuningdek dizel dvigatelli Mercedes 240D’ning kiritilgani avvalgi tahlillar bilan bevosita taqqoslash imkonini berish uchun saqlab qolingan.”

Manba

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

Misollar

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)

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Ma’lumot olish

Ma’lumotlar to‘plamining o‘lchamlarini aniqlash uchun dim() funksiyasidan, o‘zgaruvchilar nomlarini ko‘rish uchun esa names() funksiyasidan foydalaning:

Misol

Data_Cars <- mtcars # create a variable of the mtcars data set for better organization # Use dim() to find the dimension of the data set dim(Data_Cars) # Use names() to find the names of the variables from the data set names(Data_Cars)

Natija:

[1] 32 11
 [1] "mpg"  "cyl"  "disp" "hp"   "drat" "wt"   "qsec" "vs"   "am"   "gear"
[11] "carb"

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Birinchi ustundagi har bir qatorning nomini, ya’ni har bir avtomobil nomini olish uchun rownames() funksiyasidan foydalaning:

Misol

Data_Cars <- mtcars rownames(Data_Cars)

Natija:

 [1] "Mazda RX4"           "Mazda RX4 Wag"       "Datsun 710"         
 [4] "Hornet 4 Drive"      "Hornet Sportabout"   "Valiant"            
 [7] "Duster 360"          "Merc 240D"           "Merc 230"           
[10] "Merc 280"            "Merc 280C"           "Merc 450SE"         
[13] "Merc 450SL"          "Merc 450SLC"         "Cadillac Fleetwood" 
[16] "Lincoln Continental" "Chrysler Imperial"   "Fiat 128"           
[19] "Honda Civic"         "Toyota Corolla"      "Toyota Corona"      
[22] "Dodge Challenger"    "AMC Javelin"         "Camaro Z28"         
[25] "Pontiac Firebird"    "Fiat X1-9"           "Porsche 914-2"      
[28] "Lotus Europa"        "Ford Pantera L"      "Ferrari Dino"       
[31] "Maserati Bora"       "Volvo 142E"

O‘zingiz sinab ko‘ring »

Yuqoridagi misollardan ma’lumotlar to‘plamida 32 ta kuzatuv (Mazda RX4, Mazda RX4 Wag, Datsun 710 va h.k.) va 11 ta o‘zgaruvchi (mpg, cyl, disp va h.k.) borligini aniqladik.

O‘zgaruvchi — o‘lchash yoki sanash mumkin bo‘lgan narsa sifatida ta’riflanadi.

Quyida mtcars ma’lumotlar to‘plamidagi o‘zgaruvchilarning qisqacha tavsifi berilgan:

O‘zgaruvchi nomi	Tavsif
mpg	Mil/(AQSH) gallon
cyl	Silindrlar soni
disp	Dvigatel hajmi
hp	Umumiy ot kuchi
drat	Orqa o‘q uzatish nisbati
wt	Og‘irlik (1000 funt)
qsec	1/4 mil masofani bosib o‘tish vaqti
vs	Dvigatel (0 = V shaklidagi, 1 = qatorli)
am	Uzatmalar qutisi (0 = avtomatik, 1 = mexanik)
gear	Oldinga yurish uzatmalari soni
carb	Karbyuratorlar soni

O‘zgaruvchi qiymatlarini chiqarish

Agar biror o‘zgaruvchiga tegishli barcha qiymatlarni chiqarmoqchi bo‘lsangiz, data frame’ga $ belgisi va o‘zgaruvchi nomi orqali murojaat qiling (masalan, cyl (silindrlar)):

Misol

Data_Cars <- mtcars Data_Cars$cyl

Natija:

 [1] 6 6 4 6 8 6 8 4 4 6 6 8 8 8 8 8 8 4 4 4 4 8 8 8 8 4 4 4 8 6 8 4

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O‘zgaruvchi qiymatlarini saralash

Qiymatlarni saralash uchun sort() funksiyasidan foydalaning:

Misol

Data_Cars <- mtcars sort(Data_Cars$cyl)

Natija:

 [1] 4 4 4 4 4 4 4 4 4 4 4 6 6 6 6 6 6 6 8 8 8 8 8 8 8 8 8 8 8 8 8 8

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Yuqoridagi misollardan ko‘rinib turibdiki, aksariyat avtomobillarda 4 va 8 ta silindr bor.

Ma’lumotlarni tahlil qilish

Endi ma’lumotlar to‘plami haqida biroz tasavvurga ega bo‘lganimizdan so‘ng, uni ba’zi statistik ko‘rsatkichlar yordamida tahlil qilishni boshlashimiz mumkin.

Masalan, ma’lumotlarning statistik xulosasini olish uchun summary() funksiyasidan foydalanishimiz mumkin:

Misol

Data_Cars <- mtcars summary(Data_Cars)

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Natijadagi sonlarni tushunmasangiz, xavotir olmang. Tez orada ularni o‘zlashtirib olasiz.

summary() funksiyasi har bir o‘zgaruvchi uchun oltita statistik ko‘rsatkichni qaytaradi:

Min (ma’lumotlardagi eng kichik qiymat)
1-kvartil (25-persentil)
Median (o‘rtadagi qiymat — 50-persentil)
Mean (o‘rtacha qiymat)
3-kvartil (75-persentil)
Max (ma’lumotlardagi eng katta qiymat)

Keyingi boblarda ularning barchasini boshqa statistik ko‘rsatkichlar bilan birga ko‘rib chiqamiz.

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