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[英]Extract the single value from a 1 x 1 data.frame produced with dplyr as a vector?
[英]How to arrange a 2x2 data.frame from a single vector
我有以下data.frame:
v1<-c("8/12/2018", "hello, how are you", "9/9/2016", "What is going on?","the number three", "9/18/2015", "hello", "9/8/1999","not going", "where to next?")
(df<-as.data.frame(v1, stringsAsFactors=FALSE))
v1
1 8/12/2018
2 hello, how are you
3 9/9/2016
4 What is going on?
5 the number three
6 9/18/2015
7 hello
8 9/8/1999
9 not going
10 where to next?
我想生成一个函数,该函数将读取每一行,并将带日期的行之后的每一行移动到新列,并删除所有不跟随日期的行。 基于上面的示例,我想要的输出如下:
v1 value
1 8/12/2018 hello, how are you
2 9/9/2016 What is going on?
3 9/18/2015 hello
4 9/8/1999 not going
我的直觉是复制v1
然后lead
它,并使用ifelse
来创建一个新列,如下所示,但是我没有运气,甚至不确定从那里去哪里。
df$value<-ifelse(v1="^\d{1,2}\/\d{1,2}\/\d{4}$", lead(v1),"NA")
使用grep
基本R选项。 首先找出严格遵循日期格式的索引,然后使用该索引的下一行创建带有新列的新数据框。
inds <- grep("^\\d{1,2}/\\d{1,2}/\\d{4}$", df$v1)
with(df, data.frame(v1 = v1[inds], value = v1[inds + 1]))
# v1 value
#1 8/12/2018 hello, how are you
#2 9/9/2016 What is going on?
#3 9/18/2015 hello
#4 9/8/1999 not going
一种选择是创建从“V1”的新列作为lead
的列和filter
以数字或仅启动元素Date
的“V1”格式
library(tidyverse)
df %>%
mutate(value = lead(v1)) %>%
filter(grepl("^\\d+", v1))
#or
#filter(!is.na(mdy(v1)))
# v1 value
#1 8/12/2018 hello, how are you
#2 9/9/2016 What is going on?
#3 9/18/2015 hello
#4 9/8/1999 not going
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