student<-data.frame(ID=c(11,12,13),Name=c("Devin","Edward","Wenli"),Gender=c("M","M","F"),Birthdate=c("1984-12-29","1983-5-6","1986-8-8”))
另外也可以使用read.table() read.csv()读取一个文本文件,返回的也是一个Data Frame对象。读取数据库也是返回Data Frame对象。
which语句Description
Give the TRUE indices of a logical object, allowing for array indices.
Usage
which(x, arr.ind = FALSE, useNames = TRUE)
arrayInd(ind, .dim, .dimnames = NULL, useNames = FALSE)