Question

我有以下数据

data <- data.frame(make=c("af455f5","255tfd4d3","ojt100","12unin234mimo24","sh469dh","6ht6k778k9","kjh457"),
               type=c("a","a","a","a","b","a","b"))

如果相应的类型是“a”，我只想从“make”元素中提取任何三位数字。

我尝试过使用gsub，但似乎只能提取组合字符串中的所有数字。

我正在寻找的结果如下

result <- c("455","255","100","234","778")

Answer 1

这看起来像你想要的那样。

library(stringr)
str_extract(data$make,"[0-9]{3}")[data$type=="a"]

结果：

[1] "455" "255" "100" "234" "778"

希望这有帮助！

Answer 2

这是我的答案：

library(stringr)

str_extract(data$make[data$type == 'a'], '[0-9]{3}')

## "455" "255" "100" "234" "778"

Answer 3

我们可以使用base R方法

v1 <- data$make[data$type == "a"]
regmatches(v1, regexpr("[0-9]{3}", v1))
#[1] "455" "255" "100" "234" "778"

或sub

sub("^.*([0-9]{3}).*", "\\1", v1)
#[1] "455" "255" "100" "234" "778"

Answer 4

It can also be achieved using the strapplyc from gsubfn package:

result <- sapply(as.character(df$make[df$type=='a']), 
             function(x) strapplyc(x, "\\d{3}", simplify = TRUE))

output:

result
# af455f5       255tfd4d3          ojt100 12unin234mimo24      6ht6k778k9 
# "455"           "255"           "100"           "234"           "778"

R仅从字符串中提取3位数字

4 个答案: