如何从R中的字符串中删除方括号和文本

Question

I have encounter a problem in R language to process a data frame ( test_dataframe ) column ( test_column ) value like below:
Original strings in the column:

test_column
6.77[9]
5.92[10]
2.98[103]

I need to remove square brackets and any character inside square brackets , so the target value is below:

test_column
6.77
5.92
2.98

I tried with gsub function in R language, but not very lucky to resolve it, could someone help to figure out ?

Answer 1

I would use:

input <- c("6.77[9]", "5.92[10]", "2.98[103]")
gsub("\\[.*?\\]", "", input)

[1] "6.77" "5.92" "2.98"

The regex pattern \\[.*?\\] should match any quoted terms in square brackets, and using gsub would tell R to replace all such terms.

Answer 2

You can use sub and remove everything after square brackets.

df$test_column <- sub("\\[.*", "", df$test_column)
df
#  test_column
#1        6.77
#2        5.92
#3        2.98

You might want to wrap the output from the sub in as.numeric .

---

If there is always a numeric value ahead as shown in the example you can also use parse_number

readr::parse_number(df$test_column)
#[1] 6.77 5.92 2.98

data

df <- structure(list(test_column = c("6.77[9]", "5.92[10]", "2.98[103]"
)), row.names = c(NA, -3L), class = "data.frame")

Answer 3

We can use str_remove from stringr

library(stringr)
library(dplyr)
df %>%
   mutate(test_column = str_remove(test_column, "\\[.*"))
#  test_column
#1        6.77
#2        5.92
#3        2.98