double precision
On Tue, 5 Dec 2006, Yoni Schamroth wrote:
Hi,
I am attempting to query a data frame from a mysql database.
One of the variables is a unique identification number ("numeric") 18 digits
long.
I am struggling to retrieve this variable exactly without any rounding.
Read it as a character - a double is a double:
x <- 6527600583317876352 y <- 6527600583317876380 all.equal(x,y)
[1] TRUE
storage.mode(x)
[1] "double" and why they are equal is a FAQ (only ~16 digits in a double). Integer is 4-byte. Since they are IDs, not to be used for math, leave them as character strings - which they are, like telephone numbers.
The function I am using is sqlQuery(), with an ODBC connection. Querying directly results in the double being rounded towards the end (eg 6527600583317876352 instead of 6527600583317876380) Is there anyway of preserving the "numeric" class of the variable and it precision without converting it to a factor? Is the double stored as a 64-bit integer? I have attempted to use the 'dec' as well as 'as.is = TRUE', both automatically convert it to a factor which I am trying to avoid. Any advice or assistance would be greatly appreciated. Thanks Yoni Schamroth Director of Research MediaBoost LTD Tel. +972-3-5333033 (ext. 105) Fax.?+972-3-5480617 Mob.?+972-52-3422204 yoni.schamroth at compile-inc.com
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