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Time series and lm
2 messages · Marlin Keith Cox, William Dunlap
Use as.POSIXct instead of as.POSIXlt if you want to use lm() on the dates. (The data.frame() function makes this transformation for you, but you evaded data.frame() by adding the column with $<-(), which does not do the checks and transformations that data.frame() does.) Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com
-----Original Message----- From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Marlin Keith Cox Sent: Tuesday, December 17, 2013 12:49 PM To: r-help at r-project.org Subject: [R] Time series and lm Hello all, I have a time series defined by chum$Time1<-as.POSIXlt(chum$Time, format= "%m/%d/%y %H:%M") and a measured parameter pa.s When I create a linear model with(chum.skin, lm(Time1~pa.s)) I get the following error. Error in model.frame.default(formula = Time1 ~ pa.s, drop.unused.levels = TRUE) : invalid type (list) for variable 'Time1' I cannot figure it out. Keith M. Keith Cox, Ph.D. Principal MKConsulting 17105 Glacier Hwy Juneau, AK 99801 U.S. 907.957.4606 [[alternative HTML version deleted]]
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