Copyright © 2017 Xiaowan Liu
In order to get R'resources more conveniently, I summary some useful commands in this article which is benefical to my R language's studying and is facilitate search for everyone surffing the net
Starting browser， provide help with the format of HTML
Allowing you to search something using any method which you want to employ
To see the demo of a topic
Showing all of the names of Objects in the current environment
Be equal to each other
rep(x,times=5) & rep(x,each=5)
value could equal
judging whether x has NA element
judging whether x has NAN element
logical, indicating whether or not strings should be printed with surrounding quotes.
paste vector x and y together use
y <-x[-(1:5)]: exclude x[1:5]
access an object’s attributes.
as.character(x) & as.integer(digits)
returns (a copy of) its argument with its class attribute removed.
encode a vector as a factor.
provides access to the levels attribute of a variable.
tapply(X, INDEX, FUN = NULL, …, default = NA, simplify = TRUE)
Apply a function to each cell of a ragged array, that is to each (non-empty) group of values given by a unique combination of the levels of certain factors.
abtain array x which is 2*3*4
array(x) & matrix(x)
ab <- a%o% b or ` ab <- outer(a,b,”*”)