BAO HUYEN_24Mar2020

BAI MO DAU

R: Statistical and graphical programming language

Hai nguoi sang tao ra R la 2 nha thong ke hoc ten la Ross Ihaka vaf Robert Gentleman.

CAI DAT & TAI LIEU THAM KHAO

Tai phan mem tai web co ten Comprehensive R Archive Network (CRAN); http://cran.R-project.org

Cai dat package can thiet (lattice, Hmisc, rms, Epi, epitools, foreign, Rmeta, metafor, survival, Zelig, genetics, BMA, ggplot2, psych) )

Du lieu thuc hanh tai web: www.statistics.vn/data.

R for beginners (cua Emmanuel Paradis): http://cran.r-project.org/doc/contrib/rdebuts_en.pdf

Using R for data analysis and graphics (cua John Maindonald): http://cran.r-project.org/doc/contrib/using R.pdf

Tom luoc cac lenh hay su dung trong R (N.V.Tuan): http://cran.r-project.org/doc/contrib/Intro_to_R_Vietnames.pdf

VAN PHAM

LENH (command) hoac (function) thinh thoang de cap den la “HAM”

Reg <- lm (y~x)

Reg: object

lm: ham

y~x: thong so cua ham

DE BIET 1 HAM CAN CO NHUNG THONG SO NAO:

+ args(x) : Args la viet tat cua Arguments

+ help (x) hoac ?(x)

GOI Y TIM HAM: apropos (“x”)

MOI TRUONG VAN HANH

+ setwd(“c:works/stats”)

+ R co kha nang doc du lieu truc tiep tu mang (tu cac website): setwd(“http:r.ykhoanet.com”)

+ De biet hien nay, R dang “lam viec” o directory nao, chung ta chi can lenh: getwd()

PROMPT MAC DINH CUA R LA “>”; thay doi bang cach > options(prompt=“Huyen >”)

KY HIEU

- x = 5 x bang 5

- x != 5 x khong bang 5

- y < x, y > x y nho hon x, y lon hon x

- z <= 7, p >= 1 lon hon hoac bang/nho hon hoac bang

- is.na(x) Co phai x la bien so trong (missing value)

- A & B A va B (AND)

- A | B A hoac B (OR)

- ! Khong la (NOT)

KHONG NEN DAT TEN 1 OBJECT GIONG NHU 1 BIEN SO TRONG 1 DU LIEU. Tuy nhien, neu data.frame ten la data thi chung ta co the de cap den bien so age voi 1 ky tu $ nhu sau: data$age. (Tuc la bien so age trong data.frame data)