R语言学习(一)

来源：互联网发布：centos 7.4搭建lnmp 编辑：程序博客网时间：2024/04/29 07:32

 大年初一，看了看春晚的开头，闲极无聊，正好手边有从同事那借来的《学习R》这本书，那就学学吧，说不定以后会用到，顺便逃避爸妈催婚，单身狗的春节就是受虐！(PS:公司老大常常说我，学那么多东西，用不到，有啥用？我没有反驳过，其实我一直想说，如果我不学，恐怕永远不会有机会用到！) 从哪开始呢？安装？IDE? 很简单，IDE使用Rstudio 就可以啦，原因？很流行，大家都在用，就这么简单！

    #序列#生成序列，可指定步长seq.int(1,10,2)seq.int(0.1,0.01,-0.01)#seq_len() #seq_along() 创建一个从1开始、长度为其输入值得序列pp <- c("this","is","a","test","!!!")for(i in seq_along(pp)) print(pp[i])#长度 length()length(pp)nchar(pp) #序列中每个字符串的长度

#矩阵 matrixx <- matrix(1:6,nrow = 3,ncol = 2)#创建矩阵 4*3 mamatrix(1:6,nrow = 4,ncol = 3,dimnames = list(c("one","two","three","four"),c("ein","zwei","drei")))#byrow = TRUE 按行填充matrix(1:12,nrow = 4,byrow = TRUE,dimnames=list(c("one","two","three","four"),c("ein","zwei","drei")))#矩阵维度 dimdim(x)#绝阵属性attributes(x)#创建矩阵y <- 1:6dim(y) <- c(2,3) #2 row 3col#矩阵拼接y1 <- matrix(1:6,nrow = 2,ncol = 3)rbind(y,y1)#行拼接cbind(y,y1)#列拼接#转置矩阵t(x)# 内乘 %*% 外乘%o%

#列表 和向量vector最大的不同：list可以存储不同类型的数据l <- list("a",2,10,3+4i,TRUE)#列表元素命名 类似于mapl1 <- list(a=1,b=2,c=3)l2 <- list(c(1,2,3),c(4,5,6,7))#矩阵命名x <- matrix(1:6,nrow = 2,ncol = 3)dimnames(x) <- list(c("a","b"),c("c","d","e"))

#数组x <- array(1:24,dim = c(4,6))#4个两行3列的矩阵x1 <- array(1:24,dim = c(2,3,4))

#数据框#创建df <- data.frame(id = c(1,2,3,4),name= c("a","b","c","d") , gender = c(TRUE,FALSE))#行 列nrow(df)ncol(df)df2 <- data.frame(id = c(1,2,3,4),score=c(80,80,90,100) )#转换成矩阵data.matrix(df2)

#因子x <- factor(c("female","female","male","male","female"))y <- factor(c("female","female","male","male","female"),levels = c("male","female"))#因子属性table(x)#去掉属性unclass(x)#缺失值 NA/NAN  NAN只表示数值缺失 NA是有属性的#is.na() is.nan()x1 <- c(1,NA,2,NA,3)is.na(x1) #NA 返回truegl()#生成因子水平gl(3,1,6,labels = c("A","C","B"))#交替

#日期x <- date()#字符串class(x)x2 <- Sys.Date()class(x2)x3 <- as.Date("2016-02-06")weekdays(x3) #星期months(x3) #月份quarters(x3) #季度julian(x3) #距离1970 01 01 多少天#运算x4 <- as.Date("2015-09-03") #相差多少天x4-x3as.numeric(x4-x3) #只输出数值#时间x <- Sys.time()p <- as.POSIXlt(x)class(x)names(unclass(p))p$secp$minp$houras.POSIXct(p)#字符串转换为时间x1 <- "2016-02-06 00:37"strptime(x1,"%Y-%M-%d %H:%M")

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