循環遍歷數據框以搜索多個模式並報告它們

Question

我正在嘗試製作一個循環，用於統計數據框的多行中的多個模式並報告新數據框中出現的次數。

這是我輸入：模式我想搜索

input <- data.frame(V1 = LETTERS[1:4], 
      V2 = c("ABCDEF", "AAABBBCCA", "CCAABBCC", "ACCCCCCA"), 
      stringsAsFactors = FALSE) 

列表：

list<-c("ABC", "AA", "CC", "CCCC", "A") 

和預期輸出：

structure(list(V1 = structure(1:4, .Label = c("A", "B", "C", 
"D"), class = "factor"), V2 = structure(c(2L, 1L, 4L, 3L), .Label = c("AAABBBCCA", 
"ABCDEF", "ACCCCCCA", "CCAABBCC"), class = "factor"), ABC = c(1L, 0L, 0L, 0L), AA = c(0L, 1L, 1L, 0L), CC = 0:3, CCCC = c(0L, 0L, 0L, 1L), A = c(1L, 4L, 2L, 1L), ABC_length = c(1L, 0L, 0L, 0L), AA_length = c(0L, 1L, 1L, 0L), CC_length = structure(1:4, .Label = c("0", "1", "1,1", "2"), class = "factor"), CCCC_length = c(0L, 0L, 0L, 1L), A_length = structure(c(1L, 4L, 3L, 2L), .Label = c("1", "1,1", "2", "3,1"), class = "factor")), .Names = c("V1", "V2",  "ABC", "AA", "CC", "CCCC", "A", "ABC_length", "AA_length", "CC_length",  "CCCC_length", "A_length"), class = "data.frame", row.names = c(NA, -4L)) 

一種解決方案可以使用str_count或str_locate_all，下面的例子。 但實際上我想用上面提到的模式列表進行搜索。

library(stringr) 
input$ABC <- str_count(input$ABC, "ABC") 
input$ABC_length <- lapply(str_locate_all(input$ABC_length, "ABC"), function(x) { 
    paste(x[, 2] - x[, 1] + 1, collapse = ",") 
}) 

Answer 1

您在正確的軌道上，但是您指的是公式右側的所需輸出。取而代之的

input$ABC <- str_count(input$ABC, "ABC") 

（這是沒有意義的，因爲input$ABC還尚未創建），嘗試

input$ABC = str_count(input$V2, "ABC") 

類似的邏輯input$ABC_length：你需要參考input$V2，不input$ABC_length，上等式的右邊。