R语言中基本的数据单位是向量（vector），通过对于向量的堆叠我们能组合出更进阶的数据结构。这些数据结构包括弹性容器：list；有阶阶层的向量：factor；数据框：data.frame；二维的向量：matrix；阵列：array。
1. list
若我们用向量c()存储数据，因为其中有文字向量，所以在所有数据都会变成文字向量。
# 以朱元璋为例
name = "zhuyuanzhang"
nickname = c("zhuchongba","zhuguorui","zhubaba")
gender = "man"
profession = "emperor"
birthAndDead = "1328-1398"
age = 70
zyz = c(name,nickname,gender,profession,birthAndDead,age)
zyz
# [1] "zhuyuanzhang" "zhuchongba" "zhuguorui"
# [4] "zhubaba" "man" "emperor"
# [7] "1328-1398" "70"
若我们用list来储存，将宣告好的不同数据存储进去。我们可以看到list的强大收纳能力，他用数个[[索引值]]将各个向量依序放入其中。在list中各个向量依然保有自己的类型。
zyzList = list(name,nickname,gender,profession,birthAndDead,age)
zyzList
# [[1]]
# [1] "zhuyuanzhang"
# [[2]]
# [1] "zhuchongba" "zhuguorui" "zhubaba"
# [[3]]
# [1] "man"
# [[4]]
# [1] "emperor"
# [[5]]
# [1] "1328-1398"
# [[6]]
# [1] 70
# 查看各个数据的类型
str(zyzList)
# List of 6
# $ : chr "zhuyuanzhang"
# $ : chr [1:3] "zhuchongba" "zhuguorui" "zhubaba"
# $ : chr "man"
# $ : chr "emperor"
# $ : chr "1328-1398"
# $ : num 70
list中选取数据的时候可以用[[索引值]]、[[“名称”]]和$名称。
# 上方的list只能有[[索引值]]来查找，因为我们没有给各个变数命名
zyzList[[2]][2]
# [1] "zhuguorui
# 增加下变数名称,就可以用[[“名称”]]和$名称来查找数据了
zyzListPro = list(Name = name,
Nickname = nickname,
Gender = gender,
Profession = profession,
BandD = birthAndDead,
Age = age)
zyzListPro[["Nickname"]]
zyzListPro[["Nickname"]][1]
zyzListPro$Nickname
zyzListPro$Nickname[1]
# [1] "zhuchongba" "zhuguorui" "zhubaba"
# [1] "zhuchongba"
# [1] "zhuchongba" "zhuguorui" "zhubaba"
# [1] "zhuchongba"
# 可以任意组合提取
sprintf("%s is a %s, maybe his age is %.2f",
zyzListPro$Name,
zyzListPro$Profession,
zyzListPro$Age*2)
# [1] "zhuyuanzhang is a emperor, maybe his age is 140.00"
1.factor
R语言中很独特的一个数据结构就是factor。他是一种有阶层的向量（levels），一般叫他因子或是因素向量。
fourSeasons = c("spring", "summer", "autumn", "winter")
class(fourSeasons) # 文字向量
# [1] "character"
fourSeasonsFactor = factor(fourSeasons)
fourSeasonsFactor
class(fourSeasonsFactor) # 因子
# [1] spring summer autumn winter
# Levels: autumn spring summer winter
# [1] "factor"
预设的阶层（lever）是以A-Z的字母排序的（Levels: autumn spring summer winter），不过设置factor中的参数ordered = TRUE 与 levels = ，就可以根据自己的偏好做排序。
fourSeasonsFactor = factor(fourSeasons,ordered = TRUE,levels = c("summer", "winter", "spring", "autumn"))
fourSeasonsFactor
# [1] spring summer autumn winter
# Levels: summer < winter < spring < autumn
Console印出的lever会按照大小关系做排序，所以factor很适合用在有隐含顺序意义的文字向量。
temperatures = c("warm", "hot", "cold")
temperaturesFactor = factor(temperatures, ordered = TRUE, levels = c("cold", "warm", "hot"))
temperaturesFactor
# [1] warm hot cold
# Levels: cold < warm < hot
file
本文由博客一文多发平台 OpenWrite 发布！
