摘要： mycars <- c("mpg",'hp','wt') head(mtcars[mycars]) summary(mtcars[mycars]) mystats <- function(x,na.omit=FALSE){ #偏度峰度 if (na.omit) x <- x[!is.na(x)] m <- mean(x) n <- length(x) s <- sd(x) skew <- sum( 阅读全文

摘要： library(vcd) head(Arthritis) table(Arthritis$Treatment,Arthritis$Improved) with(Arthritis,table(Treatment,Improved)) mytable <- xtabs(~Treatment+Improved,data = Arthritis) with(Arthritis,xtabs(~Treatm 阅读全文