无法获取：一个输入文件中缺少但存在于其他文件中的列应在输出文件中返回 NA

问：

我有各种txt文件，其中每个文件都包含多个列，但并非所有列都存在于所有文件中。 例如

Txt 文件1 的列

D/T  City_Name  Temp  Pres  Wind_Hor  Wind_Ver  S_Moist  Temp1  Pres1  Wind1  S_Moist1
20200101  Mi  27  1019  287  278  78  1  2  2  1
20200101  Mi  28  1019  289  277  78  2  2  1  3

txt 文件的列2

D/T  City_Name  Temp  Wind_Hor  Rainf  S_Moist   Temp1  Wind1  S_Moist1
20200501  Ch  29  88  74  78  2  2  2  3
20200501  Ch  26  83  74  76  2  3  3  3

Txt 文件的列3

D/T  City_Name  Pres  Wind_Vert  Rainf  S_Moist  Pres1  Wind1  Rainf1  S_Moist1    
20180701  Ny  1017  247  78  78  4  2  2  2
20180702  Ny  1017  249  79  79  2  3  3  3

我在 R 中运行了一个代码来处理这些文件，并为每个 txt 文件获取 1 个输出 csv。

我想要的输出是在所有输出文件中都有所有 7 列，如果输入中没有特定列，那么它应该在输出中具有 NA 值。

Txt File1 的所需输出列

D_T  City_Name  Temp  Pres  Wind_Hor  Wind_Ver  Rainf  S_Moist
202001  Mi  26  1018  288  277  NA  77
202002  Mi  27  1018  288  278  NA  77

Txt 文件2 的所需输出列

D_T  City_Name  Temp  Pres  Wind_Hor  Wind_Ver  Rainf  S_Moist
202005  Ch  28  NA  287  NA  77  77
202006  Ch  27  NA  284  NA  79  78

Txt 文件的期望输出列3

D_T  City_Name  Temp  Pres  Wind_Hor  Wind_Vert  Rainf  S_Moist   
201807  Mi  NA  1016  NA  276  77  79
201808  Mi  NA  1016  NA  276  77  81

我的代码如下：

library(data.table)
library(tidyr)
library(dplyr)
library(lubridate)

setwd("D:/Test3")

dirlist <- list.files(full.names = FALSE, no.. = TRUE) 

#Read the files
read_the_files <- function(filelist){
  lapply(filelist, function(file) {
    fread(file, skip = "D/T\tXY [XY]")             
  })
}

#Adjusting with Columns
adj_col_names <- function(dt_list){
  lapply(dt_list, FUN = function(x){
    #replace [] with () as use of [] may lead to issues
    colnames(x) <- gsub("\\[", "(", colnames(x))
    colnames(x) <- gsub("\\]", ")", colnames(x))

    #Applying quality codes given in the data and range given in paper
    if ("Temp1" %in% colnames(x)) {
      x[Temp1 != 5, Temp := NA]
      x[Temp < 0 | Temp > 40, Temp := NA]
    }

    if ("Pres1" %in% colnames(x)) {
      x[Pres1 != 5, Pres := NA]
      x[Pres < 1000 | Pres > 1300, Pres := NA]
    }

for (idx in seq_along(dirlist)){
  filelist <- list.files(path = dirlist[idx], full.names = TRUE, recursive = TRUE, pattern = 
                       ".txt$")
  dt_ <- read_the_files(filelist)
  dt.tidied <- adj_col_names(dt_)

  #bind, filling missing columns to NA  
  merged <- rbindlist(dt.tidied, fill = TRUE, use.names = TRUE)

  #Choosing the columns in the output    
  sel_col <- c('D/T', 'City_Name', 'Temp', 'Pres', 'Wind_Hor', 'Wind_Ver', 'Rainf', 'S_Moist')

  #calculating monthly average
  avg_mn <- merged %>%      
    select(any_of(sel_col)) %>%
    as_tibble() %>%
    group_by(D_T = lubridate::floor_date(`D/T`, "1 month")) %>%         
    summarise(across(where(is.numeric), ~ if(mean(is.na(.x)) > 0.1) NA else mean(.x, na.rm = TRUE)))     #summarise only numeric columns
    write.csv(paste0(dirlist[idx],"_mn.csv"))

由于各种依赖关系，我无法更改我的代码。我只能修改。谁能帮我修改它以获得所需的输出？

根据 jkatam 的回答测试了代码：

dfs1 <- list.files(path = 'D:/Test3', pattern = "*txt", recursive = TRUE)
var <- c('D/T', 'City_Name', 'Temp', 'Pres', 'Wind_Hor', 'Wind_Ver', 'Rainf', 'S_Moist')
lapply(dfs1, \(x) {
  dfn <- get(x, envir = .GlobalEnv)
  dfn[[var[which(is.na(match(var,names(dfn))))]]] <- NA
  dfn <- dfn %>% select(all_of(var))
  return(assign(x,dfn,envir = .GlobalEnv))
})

我收到错误：

Error in get(x, envir = .GlobalEnv) :
object 'Mi/Mi_2020-01_0100.txt' not found