从/到特定单词从 R 中的字符向量中提取字符串

Question

Here is an example of a character vector that I have, I need to extract all strings between "## Code:" and "## My table". I understand I can do this by position using text[4:8] , however the length of code to extract will vary so I need a solution that doesn't depend on fixed position.

text <- c("## Author: user", "## Data = data.txt", "## Code:", "temp(){", "x = a1 + b1", "a1(b1 = 3)", "tf(cov = c(,1,))", "}", "## My table")

The new character vector should contain this: c("temp(){", "x = a1 + b1", "a1(b1 = 3)", "tf(cov = c(,1,))", "}")

Thanks for helping me arrive at a solution.

Answer 1

We can create a logical index with == , and then wrap with which

text[which(cumsum(text == "## Code:"|text ==  "## My table") == 1)[-1]]
#[1] "temp(){"          "x = a1 + b1"      "a1(b1 = 3)"       "tf(cov = c(,1,))" "}"  

Or with which find the start and end locations and use : to get the sequence of positions for extracting the elements

text[(which(text == "## Code:")[1] +1):(which(text ==  "## My table")-1)]