r - 从向量 R 中提取带小数的数字

Question

我有以下向量:

c("c(`Kruskal-Wallis chi-squared` = 201.760850624131)", "c(df = 17)", 
"1.26686891197831e-33", "Kruskal-Wallis rank sum test", "delta_Z by criteria"
)

我想要这样的输出:

c("201.760850624131", "17", "1.26686891197831e-33")

感谢您的帮助

Answer 1

我们可以在这里尝试使用 str_extract 作为正则表达式选项:

x <- c("c(`Kruskal-Wallis chi-squared` = 201.760850624131)",
       "c(df = 17)", 
       "1.26686891197831e-33",
       "Kruskal-Wallis rank sum test",
       "delta_Z by criteria"
)
output <- as.numeric(na.omit(str_extract(x, "\\d+(?:\\.\\d+)?(?:e[+-]\\d+)?")))
output

[1] 2.017609e+02 1.700000e+01 1.266869e-33

正则解释:

• \\d+匹配一个整数部分
• (?:\\.\\d+)?可选的小数部分
• (?:e[+-]\\d+)? 可选指数(正或负)