R Packages stringr - str_split | R包stringr - str_split

 

stringr的函數系列進入尾聲，最後一個介紹的是str_split，也就是拆解，拆解完成返回向量或是矩陣的型態

基本語法

str_split(dataset$string, 拆解的字元或字串)

str_split(dataset$string, 拆解的字元或字串, n)

可用參數

simplify = TRUE，預設為FALSE，若為TRUE，則拆解為矩陣

n = 矩陣組數

建立數據框

stringr_df <- tibble(animal = c(

    "dog chase cat",

    "rat eat fish",

    "lion or tiger or wolf")

    )

# 輸出結果

r$> stringr_df # A tibble: 3 x 1 animal <chr> 1 dog chase cat 2 rat eat fish 3 lion or tiger or wolf

將連接的詞句拆解

# 拆解連接詞

str_split(stringr_df$animal, "chase | eat | or")

# 輸出結果

r$> str_split(stringr_df$animal, "chase | eat | or") [[1]] [1] "dog " " cat" [[2]] [1] "rat " " fish" [[3]] [1] "lion " " tiger " " wolf"

# 拆解連接詞並返回矩陣

str_split(stringr_df$animal, "chase | eat | or", simplify = TRUE)

# 輸出結果

r$> str_split(stringr_df$animal, "chase | eat | or", simplify = TRUE) [,1] [,2] [,3] [1,] "dog " " cat" "" [2,] "rat " " fish" "" [3,] "lion " " tiger " " wolf"

拆解完成後返回矩陣型態，n設定為返回的矩陣數，依照設定數字進行拆解返回，僅返回符合設定值的拆解，以例子來看會較清楚，若設定超過字串數，則返回空矩陣

# 拆解連接詞並返回矩陣，n = 1

str_split_fixed(stringr_df$animal, "chase | eat | or", 1)

# 輸出結果

r$> str_split_fixed(stringr_df$animal, "chase | eat | or", 1) [,1] [1,] "dog chase cat" [2,] "rat eat fish" [3,] "lion or tiger or wolf"

# 拆解連接詞並返回矩陣，n = 2

str_split_fixed(stringr_df$animal, "chase | eat | or", 2)

# 輸出結果

r$> str_split_fixed(stringr_df$animal, "chase | eat | or", 2) [,1] [,2] [1,] "dog " " cat" [2,] "rat " " fish" [3,] "lion " " tiger or wolf"

# 拆解連接詞並返回矩陣，n = 3

str_split_fixed(stringr_df$animal, "chase | eat | or", 3)

# 輸出結果

r$> str_split_fixed(stringr_df$animal, "chase | eat | or", 3) [,1] [,2] [,3] [1,] "dog " " cat" "" [2,] "rat " " fish" "" [3,] "lion " " tiger " " wolf"