R 以数字格式而非字符格式从网站读取数据集

使用下面的代码，我从网站上读取数据。
问题是它将数据读取为

字符

而不是

数字

格式，特别是一些列，如“Enlem（N）和Boylam（E）”

我怎样才能解决这个问题

library(rvest)

widths <- c(11,10,10,10,14,5,5,5,48,100)
dat <- "http://www.koeri.boun.edu.tr/scripts/lst5.asp" %>%
    read_html %>%
    html_nodes("pre") %>%
    html_text %>%
    textConnection %>%
    read.fwf(widths = widths, stringsAsFactors = FALSE) %>%
    setNames(nm = .[6,]) %>%
    tail(-7) %>%
    head(-2)

库（rvest）
宽度%
html_节点（“前”）%%>%
html_文本%>%
text连接%>%
read.fwf（宽度=宽度，stringsAsFactors=假）%>%
集合名（nm=[6，]）%>%
尾部（-7）%>%
总目（-2）

如果您知道哪些特定列应该是数字，您可以将这些列转换为数字。如果您不知道哪些列应该是数字，您可以创建一个函数来查看数据，如果列中的大小写百分比足够大，则将该列更改为数字。我使用了下面的函数为此目的：

NumericColumns <- function(x, AllowedPercentNumeric =.95, PreserveDate=TRUE, PreserveColumns){

  # find the counts of NA values in input data frame's columns
  param_originalNA <- apply(x, 2, function(z){sum(is.na(z))})

  # blindly coerce data.frame to numeric
  df_JustNumbers <- suppressWarnings(as.data.frame(lapply(x, as.numeric)))

  # Percent Non-NA values in each column
  PercentNumeric <- (apply(df_JustNumbers, 2, function(x)sum(!is.na(x))))/(nrow(x)-param_originalNA)

  rm(param_originalNA)

  # identify columns which have a greater than or equal percentage of numeric as specified
  param_numeric <- names(PercentNumeric)[PercentNumeric >= AllowedPercentNumeric]

  # Remove columns from list to convert to numeric that are specified as to preserve
  if (!missing(PreserveColumns)){param_numeric <- setdiff(param_numeric, PreserveColumns)}

  # Identify columns that are dates initially
  IsDateColumns <- lapply(x, function(y)(is(y, "Date")|is(y, "POSIXct")))
  param_dates <- names(IsDateColumns)[IsDateColumns==TRUE]

  # Remove dates from list if specified to preserve dates
  if (PreserveDate){param_numeric <- setdiff(param_numeric, param_dates)}

  # returns column position of numeric columns in target data frame
  param_numeric <- match(param_numeric, colnames(df_JustNumbers))

  # removes NA's from column list
  param_numeric <- param_numeric[complete.cases(param_numeric)]

  # coerces columns in param_numeric to numeric and inserts numeric columns into target data.frame
  if(length(param_numeric)==1){
    suppressWarnings(x[, param_numeric] <- as.numeric(x[, param_numeric]))
  }

  if(length(param_numeric)>1){
    suppressWarnings(x[, param_numeric] <- apply(x[, param_numeric],2, function(x)as.numeric(x)))
  }

  return(x)
}

---

NumericColumns您可以将
as.numeric
列？（即
dat$Enlem（N））看起来都是以字符形式读入的，因为第一次读入表格时，前7行中有列描述，稍后将删除。
# Use function to convert to numeric 
dat <- NumericColumns(dat)