R語言中基本的數據單位是向量（vector），通過對於向量的堆疊我們能組合出更進階的數據結構。這些數據結構包括彈性容器：list；有階階層的向量：factor；數據框：data.frame；二維的向量：matrix；陣列：array。
1. list
若我們用向量c()存儲數據，因為其中有文字向量，所以在所有數據都會變成文字向量。
<code># 以朱元璋為例
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" /<code>
若我們用list來儲存，將宣告好的不同數據存儲進去。我們可以看到list的強大收納能力，他用數個[[索引值]]將各個向量依序放入其中。在list中各個向量依然保有自己的類型。
<code>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
# 查看各個數據的類型
str(zyzList)
# List of 6
# $ : chr "zhuyuanzhang"
# $ : chr [1:3] "zhuchongba" "zhuguorui" "zhubaba"
# $ : chr "man"
# $ : chr "emperor"
# $ : chr "1328-1398"
# $ : num 70/<code>
list中選取數據的時候可以用[[索引值]]、[[“名稱”]]和$名稱。
<code># 上方的list只能有[[索引值]]來查找，因為我們沒有給各個變數命名
zyzList[[2]][2]
# [1] "zhuguorui
# 增加下變數名稱,就可以用[[“名稱”]]和$名稱來查找數據了
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"
# 可以任意組合提取
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"/<code>
1.factor
R語言中很獨特的一個數據結構就是factor。他是一種有階層的向量（levels），一般叫他因子或是因素向量。
<code>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"/<code>預設的階層（lever）是以A-Z的字母排序的（Levels: autumn spring summer winter），不過設置factor中的參數ordered = TRUE 與 levels = ，就可以根據自己的偏好做排序。
<code>fourSeasonsFactor = factor(fourSeasons,ordered = TRUE,levels = c("summer", "winter", "spring", "autumn"))
fourSeasonsFactor
# [1] spring summer autumn winter
# Levels: summer < winter < spring < autumn/<code>Console印出的lever會按照大小關係做排序，所以factor很適合用在有隱含順序意義的文字向量。
<code>temperatures = c("warm", "hot", "cold")
temperaturesFactor = factor(temperatures, ordered = TRUE, levels = c("cold", "warm", "hot"))
temperaturesFactor
# [1] warm hot cold
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