Replacing commas and dots in R

问题:

I have a whole column of numbers that include dot separators at the thousands and comma instead of dot as an dismal separator. When I try to create a numeric column out of them, I lose all data.

var1 <- c("50,0", "72,0", "960,0", "1.920,0", "50,0", "50,0", "960,0")
df <- cbind(var1, var2 = as.numeric(gsub(".", "", as.character(var1))))

and wound up with:

 var1      var2
[1,] "50,0"    NA  
[2,] "72,0"    NA  
[3,] "960,0"   NA  
[4,] "1.920,0" NA  
[5,] "50,0"    NA  
[6,] "50,0"    NA  
[7,] "960,0"   NA 

What am I doing wrong?

回答1:

You need to escape the "." in your regular expression, and you need to replace the commas with a "." before you can convert to numeric.

> as.numeric(gsub(",", ".", gsub("\\.", "", var1)))
[1]   50   72  960 1920   50   50  960

回答2:

For things like these I like scan() the most, because it is easy to understand. Just use

scan(text=var1, dec=",", sep=".")

Alas, it's not faster than gsub(), which on the other hand seemes overpowered. Hence another, and fast, option is sub():

as.numeric(sub(",", ".", sub(".", "", var1, fixed=TRUE), fixed=TRUE))

And just in case: When you're reading var1 from a file directly, just read it in with a specified separator: read.table("file.txt", dec=",", sep=".")

回答3:

You can use function "type_convert", from "readr" package. I am reading an ODS file (Locale Portuguese), and converting the numbers:

library('readODS')
library('tidyverse')
data <- read_ods('mod-preditivo.ods', sheet=1,col_names = TRUE,range='a1:b30',col_types=NA)
df <- type_convert(data,trim_ws=TRUE,col_types = cols(Pesos=col_integer(),Alturas=col_double()),locale = locale(decimal_mark = ","))
str(df)