Question

我有一些数据如下所示

        date         over     bed.bath
1 2016-03-17 -0.002352941 1 bed 1 bath
2 2016-03-17 -0.035294118 1 bed 1 bath
3 2016-03-17 -0.008278717 1 bed 1 bath
4 2016-03-17 -0.008350731 1 bed 1 bath
5 2016-03-17  0.004243281 1 bed 2 bath
6 2016-03-17  0.007299270 2 bed 2 bat

bed.bath列是character。我想分别提取有关床和浴的信息。我试过拆分字符串并提取出这样的数字

getbeds <- function(x){

  splits = strsplit(x," ")

  return(splits[[1]][1])
}

但是，当我使用df<- df%>% mutate(beds = getbeds(bed.bath))时，新列只有1秒。

        date         over     bed.bath beds
1 2016-03-17 -0.002352941 1 bed 1 bath    1
2 2016-03-17 -0.035294118 1 bed 1 bath    1
3 2016-03-17 -0.008278717 1 bed 1 bath    1
4 2016-03-17 -0.008350731 1 bed 1 bath    1
5 2016-03-17  0.004243281 1 bed 2 bath    1
6 2016-03-17  0.007299270 2 bed 2 bath    1

从数据框中提取我喜欢的信息的最佳方法是什么？

数据

df <- structure(list(date = structure(c(16877, 16877, 16877, 16877, 16877, 16877), class = "Date"),
                     over = c(-0.002352941, -0.035294118, -0.008278717, -0.008350731, 0.004243281, 0.00729927),
                     bed.bath = c("1 bed 1 bath", "1 bed 1 bath", "1 bed 1 bath", "1 bed 1 bath", "1 bed 2 bath", "2 bed 2 bath")),
                .Names = c("date", "over", "bed.bath"),
                row.names = c("1", "2", "3", "4", "5", "6"), class = "data.frame")

library('dplyr')
df %>% mutate(beds = getbeds(bed.bath))

Answer 1

我们可以使用extract

中的tidyr

library(tidyr)
library(dplyr)
df %>% 
   extract(bed.bath, into = 'beds', "(\\d+).*", remove = FALSE)

或base R使用sub匹配一个或多个空格（\\s+）后跟字符（.*）并将其替换为空格以便我们获取数字在字符串的开头，所有其他字符都被删除。

df$beds <- with(df, as.integer(sub("\\s+.*", "", bed.bath)))

OP输出中相同值的原因是因为它仅从第一个[1]元素（list）中提取第一个观察点（[[1]]）

Answer 2

If you also want to extract the number of baths, you could use sapply:

 getbeds <- function(x){

  splits = strsplit(x," ")

  as.integer( c(splits[[1]][[1]],splits[[1]][[3]]) )
}

bed.bath <- t(sapply(df$bed.bath,getbeds))

 getbeds <- function(x){

  splits = strsplit(x," ")

  c(splits[[1]][[1]],splits[[1]][[3]])
}

bed.bath <- t(sapply(df$bed.bath,getbeds))

df$bed  <- bed.bath[,1]
df$bath <- bed.bath[,2]

df
#        date         over     bed.bath bed bath
#1 2016-03-17 -0.002352941 1 bed 1 bath   1    1
#2 2016-03-17 -0.035294118 1 bed 1 bath   1    1
#3 2016-03-17 -0.008278717 1 bed 1 bath   1    1
#4 2016-03-17 -0.008350731 1 bed 1 bath   1    1
#5 2016-03-17  0.004243281 1 bed 2 bath   1    2

如何将字符串函数应用于列？

2 个答案: