R: converting float to characters gives additional decimals

Asked May 24 '17 at 01:35

Active May 24 '17 at 01:47

Viewed 57 times

I have a dataset with column called "id". I want to create a dummy variable, which is equal to 1 if "id" ends with digit 9.

UPD: "id" is represented by floating point number with 2 digit precision and various size. So, it may be 2.09, it may be 200.09.

d$end.9 <- as.numeric(str_sub(as.character(d$id), start= -1)==9)

This does not give correct result as as.character(d$id) gives, for example, 2.090000123 for d$id of 2.09 etc. I suppose the reason for this is how float numbers are handled by computers. How to achieve my goal then?

edited May 24 '17 at 01:47

asked May 24 '17 at 01:35

user3349993

1

I think your problem is poorly defined - what is the last digit of `1/7` for instance? – thelatemail May 24 '17 at 01:40
1

`((round(d$id,1)*10)%%10)==9` – HubertL May 24 '17 at 01:40
@thelatemail, my bad. added update on "id" – user3349993 May 24 '17 at 01:48
Sounds like your `id` column should be stored as character to start with. – thelatemail May 24 '17 at 01:48
`x <- as.character(d$id); as.numeric(substr(x, nchar(x), nchar(x)) == "9")` ? – Ronak Shah May 24 '17 at 01:49
@thelatemail, I need it in numeric form because it contains some additional information – user3349993 May 24 '17 at 01:50
@HubertL, thank you. I think after additional information I provided, your solution can be changed to `((round(d$id,2)*100)%%10)==9` and it will work for me – user3349993 May 24 '17 at 01:51
That doesn't make much sense to me. If it is just the form `nnn.dd` you are not losing any information by storing it as a string. – thelatemail May 24 '17 at 01:51
Very similar to https://stackoverflow.com/questions/24601887/r-change-decimal-place-without-round-off/24601941 – thelatemail May 24 '17 at 01:53
@thelatemail, indeed. In the beginning I was thinking this question is about converting to a string. And then getting the last character of the string. But I was suggested a simpler solution based on the "type" of data I had. – user3349993 May 24 '17 at 01:57

R: converting float to characters gives additional decimals

0 Answers0