R学习笔记

花花灬太岁

######判断空值NA
a = c(NA,0,0,1,0,0,0,0,0)
a
anyNA(a)


a = c(NA,0,0,1,0,0,0,0,0)
is.na(a)
which(is.na(a))

####NULL
v = c()
class(v)
length(v)
is.null(v)
#####比较大小1
m = c(1:30)
m
for (i in 1:30)
{
  if (m[i] > 10 & m[i] < 30)
    m[i] = 0
}

####2
m = c(1:30)
m
m[which(m > 10 & m < 30)] = 0
m

####盒图

d = InsectSprays
p = boxplot(count ~ spray, data = d, col = rainbow(3))
p$stats
p$out
p$group

######重复值
x = c("a","a","b","b",1,2,4,7,0,2,1)
x
unique(x)
b = c("a","b","a","b",1,2,4,)

unique(iris)

######加载数据处理包
library(plyr)

ddply(iris,.(Species,Petal.Length,Petal.Width))

ddply(iris,.(Species,Petal.Length,Petal.Width),tail,n = 1)

split(iris,iris$Species)