R语言入门一 单模式数据结构

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单模式数据结构

本学习笔记参考Andy Nicholls的R语言入门经典

载入R包

library() /require()

查看数据编码模式

mode()

查看数据类型

class()

向量(无结构）矩阵（二维）数组（多维（单一模式）

Vector

创建向量

numerciVector = c(1,2,3,4,5) #数值型向量
logicalVector  = c(T,F,T,F,TRUE,FALSE) #逻辑性向量
completeVector = c(3+4i,4+3i) #复数型向量
stringVector = c('lk','lk1')  #字符型向量
repeatedNumericVector = c(numerciVector,numerciVector,numerciVector) #重复产生向量
intSequence1 = 1:100/-1:1/c(0:4,5,4:0) #创建间隔为1的序列
intSequence2 = 2*1:50 #创建间隔为2的序列
sequence1 = seq(1,10,by = 0.5) #创建1-10，间隔为0.5的序列
sequence2 = seq(1,10,length = 10) #创建从1—10的10值序列
repeatedNumericVector1 = rep(numerciVector,3) #产生重复3次的numerciVector向量
repeatedStringVector1 = rep(stringVector,3)#产生重复3次的stringVector向量
rep(1:5,10)
rep(c('lk12','lk13'),c(2,3))
rep(c('lk12','lk13'),3)
rep(c('lk12','lk13'),each = 3)

如果向量中有多模式结构，R会把向量中的元素强制变成单模式

c(1,2,'lk12')
c(1,2,T,FALSE)

向量性质查询

mode(x)
class(x)
length(Vector)

为向量起名

genderFrequence = c(Female  = 123, Male = 100) #赋值时起名
names(genderFrequence) #查询名字
NonenameVector = c(123,100)
names(NonenameVector) = c('Female','Male') #后起名

索引向量

x = c(1,2,3,4,5,6) #创建向量
x
x[]
x[c(1:2,5)]
x[-3]
x[c(-2,-4)]
x[x > 3]
x >= 3
x == 6
x != 5
x[x>2 & x<5]
names(x) = c('a','b','c','d','e','f')
x[c('a','c']

英文字母自带序列

letters()
LETTERS()

Matrix

矩阵创建

cbind(1:3,2:4,rep(1,3))
rbind(1:3,2:4,rep(1,3))
t(Matrix)
t(cbind(1:3,2:4,rep(1,3))) == rbind(1:3,2:4,rep(1,3))
matrix(1:12,nrow = 3)
matrix(1:12,nrow = 3,byrow = F)

矩阵的性质

X = matrix(1:12,nrow = 3,byrow = F)
mode(X)
class(X)
length(X)
dim(X)
dim(X)[1]
nrow(X)
ncol(X)

给矩阵起名

X = matrix(1:12,nrow = 3,byrow = F)
dimnames(X) = list(c('18-25','26-35','36+'),c('Lk1','Lk2','Lk3','Lk4'))
dimnames(X) 

矩阵索引

X = matrix(1:12,nrow = 3,byrow = F)
X[,]
X[1,]
X[c(1,2),]
X[-1,]
X[,1]
X[,1,drop = FALSE] #保持原来维度
X[c(F,T,T),]
X[X[,1] !=2]
dimnames(X) = list(c('18-25','26-35','36+'),c('Lk1','Lk2','Lk3','Lk4'))
X[,c('Lk1','Lk2')]

Array

创建数组

aVector = c(1:12)
X = array(aVector,dim = c(3,4))
X = array(rep(aVector,3),dim = c(3,4,3))

数组属性

aVector = c(1:12)
X = array(aVector,dim = c(3,4))
mode(X)
length(X)
dim(X)

数组起名

aVector = c(1:12)
X = array(rep(aVector,3),dim = c(3,4,3))
dimnames(X) = list(letters[1:3],LETTERS[1:4],c('X1','X2','X3'))

数组索引

aVector = c(1:12)
X = array(rep(aVector,3),dim = c(3,4,3))
dimnames(X) = list(letters[1:3],LETTERS[1:4],c('X1','X2','X3'))
X[,,1]
X[-1,1:2,1:2]

Vector/Matrix/Array difference and transfer

x = 1:12 # This is a Vector
dim(x) = c(3,4) #This is a Matrix
dim(x) = c(3,2,2) #This is an Array