CODEWITHSUNDEEP
r
M.D.
M.D.

Reputation: 91

Exponential notation not precise

I have imported a dataset which contains large numbers which were automatically converted to exponential notation. Because I had to see the full number, I used options(scipen = 999). I discovered that the imported number did not equal the original number from the dataset. For example: 5765949338897345178 was changed to 5765949338897345536.

How can it be that these numbers are not the same? The weird thing is that when I use: which(dim_alias1$id == 5765949338897345536) and which(dim_alias1$id == 5765949338897345178), it returns the same rownumber. How is this possible?

Upvotes: 4

Views: 94

Answers (1)

user20650
user20650

Reputation: 25854

As you are using the variable as an id number, it doesn't need to be numeric. So set the column class to character when reading in.

Example: 

dat <- data.frame(id=12345, x=1)
write.table(dat, tmp <- tempfile())
dat2 <- read.table(tmp, colClasses = c(id="character"))
str(dat2)

#'data.frame':  1 obs. of  2 variables:
# $ id: chr "12345"
# $ x : int 1

Upvotes: 3

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