R学习笔记
######判断空值NAa = 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 > 10 & m < 30)
m = 0
}
####2
m = c(1:30)
m
m = 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)
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