r语言 - 如何强制读取器考虑正确的小数/分组标记?

Question

具有欧洲数字格式样式(1234.56 -> 1.234,56(的csv文件应由readr函数或fread()处理。尽管read_csv2()应该完全针对此任务而设计，但它基本上忽略了规范。它只会自动猜测数字格式。如果超过 3 位数字的第一个数字仅出现在文件末尾，即在达到guess_max之后(默认为 1000(，则会出现问题。

如何以编程方式强制实施正确的格式设置？

library(readr)
data <- data.frame(var1 = c("", 4, 5, "124.392,45"),
var2 = c(1, 2, "4.783.194,43", 7))
write_csv2(data, "data.csv")
read_csv2("data.csv", guess_max = 2, 
locale = locale(decimal_mark = ",", grouping_mark = "."))
# # A tibble: 4 x 2
#   var1  var2
#   <dbl> <dbl>
# 1    NA     1
# 2     4     2
# 3     5    NA
# 4    NA     7
read_csv2("data.csv", guess_max = 3, 
locale = locale(decimal_mark = ",", grouping_mark = "."))
# # A tibble: 4 x 2
#   var1  var2
#   <dbl> <dbl>
# 1    NA     1
# 2     4     2
# 3     5    4783194.
# 4    NA     7
read_delim("data.csv", delim = ";", guess_max = 3, 
locale = locale(decimal_mark = ",", grouping_mark = "."))
# # A tibble: 4 x 2
#   var1  var2
#   <dbl> <dbl>
# 1    NA     1
# 2     4     2
# 3     5    4783194.
# 4    NA     7

Answer 1

事先设置col_types似乎有所帮助。在本例中为数字。

col_number() [n], numbers containing the grouping_mark

result <- read_csv2("data.csv", 
# guess_max = 2, not needed if col_types are specified
col_types = cols(var1 = col_number(),
var2 = col_number()),
locale = locale(decimal_mark = ",", grouping_mark = "."))
result
# A tibble: 4 x 2
var1     var2
<dbl>    <dbl>
1     NA        1 
2      4        2 
3      5  4783194.
4 124392.       7 

正如 Adam 指出的那样，如果您设置了col_types，则无需猜测col_types因为需要与要读取的列长度相同。