从字符串向量中提取数字 [英] Extracting numbers from vectors of strings

问题描述

我有这样的字符串:

years<-c("20 years old", "1 years old")

我只想从这个向量中提取数字.预期输出是一个向量:

I would like to grep only the numeric number from this vector. Expected output is a vector:

c(20, 1)

我该怎么做?

推荐答案

怎么样

# pattern is by finding a set of numbers in the start and capturing them
as.numeric(gsub("([0-9]+).*$", "\\1", years))

或

# pattern is to just remove _years_old
as.numeric(gsub(" years old", "", years))

或

# split by space, get the element in first index
as.numeric(sapply(strsplit(years, " "), "[[", 1))

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