Question

一个漫长的早晨后，我放弃了！

我有以下文本文件：StationLog.txt

包含以下内容：

Version      = 2.0
StationName  = STN67_P70
BeginTime    = 2017-10-06.03:25:00
EndTime      = 2017-10-06.03:55:00
IgnoreNo     = 5000
PumpedVolume = 0

我需要提取BeginTime，EndTime和StationName，这些标题很好，因为它们的值会馈入另一段代码。

我的想法是我不必手动进行操作，因为这些文件会及时出现。

到目前为止，我还需要遵循其他各种指南：

a <- read.fwf("StationLog.txt", c(37,100), stringsAsFactors=FALSE)
a <- a[grep("=", a$V1), ]
a <- cbind(
  do.call( rbind, strsplit(a$V1, "=\\s+") )

但是碰壁，任何帮助将不胜感激！

Answer 1

基于read.table函数，您可以使用参数来执行所需的操作。

如果每行只有一个=，并且BeginTime，EndTime和StationName在所有文件中的书写都相同，则以下建议将起作用：

read.table(
  file            ="StationLog.txt",
  header          =FALSE, # No column names
  sep             ="=",   # separator character
  strip.white     =TRUE,  # remove multiple white character
  row.names       =1,     # the first column contains the rownames
  stringsAsFactors=FALSE
)[c("BeginTime", "EndTime", "StationName"), # extract the 3 infos based on their names corresponding to the rownames
  ,drop=FALSE] # keep the data.frame format

结果：

                             V2
BeginTime   2017-10-06.03:25:00
EndTime     2017-10-06.03:55:00
StationName           STN67_P70

Answer 2

如果您将整个内容读为多行字符串：

数据：

txt_string <- "Version      = 2.0
StationName  = STN67_P70
BeginTime    = 2017-10-06.03:25:00
EndTime      = 2017-10-06.03:55:00
IgnoreNo     = 5000
PumpedVolume = 0"

stationName<- regmatches(txt_string, gregexpr("StationName\\s+=\\s+\\K\\S+" ,txt_string, perl = T))
beginTime  <- regmatches(txt_string, gregexpr("BeginTime\\s+=\\s+\\K\\S+" ,txt_string, perl = T))
endTime    <- regmatches(txt_string, gregexpr("EndTime\\s+=\\s+\\K\\S+" ,txt_string, perl = T))

do.call(cbind, c(stationName, beginTime, endTime))

#     [,1]        [,2]                  [,3]                 
#[1,] "STN67_P70" "2017-10-06.03:25:00" "2017-10-06.03:55:00"

Answer 3

备用方法：

# use the filename vs this embedded example
station_info <-   readLines(textConnection("Version      = 2.0
StationName  = STN67_P70
BeginTime    = 2017-10-06.03:25:00
EndTime      = 2017-10-06.03:55:00
IgnoreNo     = 5000
PumpedVolume = 0"))

基础：

as.list(sapply(
  strsplit(station_info, split = "[[:space:]]*=[[:space:]]*"),
  function(x) setNames(x[2], x[1])
)) -> station_info

str(station_info, 1)
## List of 6
##  $ Version     : chr "2.0"
##  $ StationName : chr "STN67_P70"
##  $ BeginTime   : chr "2017-10-06.03:25:00"
##  $ EndTime     : chr "2017-10-06.03:55:00"
##  $ IgnoreNo    : chr "5000"
##  $ PumpedVolume: chr "0"

tidyverse：

library(tidyverse)

# use the filename vs this embedded example
station_info <-   readLines(textConnection("Version      = 2.0
StationName  = STN67_P70
BeginTime    = 2017-10-06.03:25:00
EndTime      = 2017-10-06.03:55:00
IgnoreNo     = 5000
PumpedVolume = 0"))

str_split(station_info, pattern = "[[:space:]]*=[[:space:]]*") %>% 
  map(~set_names(.x[2], .x[1])) %>% 
  flatten() %>% 
  str(1)

将基本版本（以避免依赖）包装为一个函数，以便您可以将其重新用于其他工作站：

read_station_metadata <- function(path) {

  path <- path.expand(path)
  stopifnot(file.exists(path))

  station_info <- readLines(path, warn = FALSE)

  as.list(sapply(
    strsplit(station_info, split = "[[:space:]]*=[[:space:]]*"),
    function(x) setNames(x[2], x[1])
  ))

}

从.txt文件中提取一些数据

3 个答案: