整理自 R語言翻轉教室
- 版本資訊 (sha-hash：4636e186)
課程進度：RBasic
- 01-RBasic-01-Introduction …ok
- 01-RBasic-02-Data-Structure-Vectors …ok
- 01-RBasic-03-Data-Structure-Object (O)
- 01-RBasic-04-Factors (O)
- 01-RBasic-05-Arrays-Matrices (O)
- 01-RBasic-06-List-DataFrame
- 01-RBasic-07-Loading-Dataset
(一) 03-Data-Structure-Object
物件結構
- 向量：最基礎的『物件』。
[屬性] mode()、length()
- mode()：查詢向量的型態。
- length()：查詢向量的值的個數。
- 型態：
logical、integer、numeric、complex、character和raw。
- 型態：
> # 用`mode`和`length`函數來查詢向量的型態和長度。
> mode(x)
[1] "numeric"
>
> length(x)
[1] 5
[屬性] attributes()、names()、class()
- attributes()：查詢物件的屬性。
- names()：查詢物件的名字。
- class()：查詢物件的類別。
> # 用`attributes`、`names`和`class`函數來查詢向量的屬性、名稱和類別。
> attributes(g)
$names
[1] "coefficients" "residuals" "effects"
[4] "rank" "fitted.values" "assign"
[7] "qr" "df.residual" "xlevels"
[10] "call" "terms" "model"
$class
[1] "lm"
>
> names(g)
[1] "coefficients" "residuals" "effects"
[4] "rank" "fitted.values" "assign"
[7] "qr" "df.residual" "xlevels"
[10] "call" "terms" "model"
>
> class(g)
[1] "lm"
>
(二) 04-Factors
- 範例：血型分類
> blood_type
[1] "B" "A" "A" "O" "AB" "O" "A" "AB" "O" "AB" "O"
[12] "AB" "A" "A" "A" "AB" "A" "AB" "AB" "A" "AB" "A"
[23] "AB" "B" "A" "O" "A" "A" "AB" "AB"
>
[屬性] factor()、levels()
- factor()：將資料轉為factor向量。
- levels()：取出向量中的類別。
> factor(blood_type)
[1] B A A O AB O A AB O AB O AB A A A AB A AB
[19] AB A AB A AB B A O A A AB AB
Levels: A AB B O
>
> blood_type_factor <- factor(blood_type)
>
> levels(blood_type_factor)
[1] "A" "AB" "B" "O"
[屬性] str()
- str()：觀察factor向量的結構。
> str(blood_type_factor)
Factor w/ 4 levels "A","AB","B","O": 3 1 1 4 2 4 1 2 4 2 ...