import re
string = "NYC experienced a temperature of 35.5 degrees centigrade"
pattern = r"\d+\.\d+"
temperature = re.search(pattern, string)
print(temperature.group())

应打印：

35.5

library(stringr)
string <- "NYC experienced a temperature of 35.5 degrees centigrade"
pattern <- "\\d+\\.\\d+"
temperature <- str_extract(string, pattern)
print(temperature)

[1] "35.5"

假设输入字符串是s，它将每个单词读入单独的data.frame列，然后使用Filter提取数字列，最后将data.frame结果转换为标量。不使用正则表达式或包。

Filter(is.numeric, read.table(text = s))[[1]]
## [1] 35.5

或者相当于这个管道

s |> read.table(text = _) |> Filter(f = is.numeric) |> as.numeric()
## [1] 35.5

如果我们有一个字符串向量ss，那么

ss <- c(s, s) # test data

f <- function(x) Filter(is.numeric, read.table(text = x))[[1]]
sapply(ss, f, USE.NAMES = FALSE)
## [1] 35.5 35.5