Displaying 2 results from an estimated 2 matches for "evap".
Did you mean:
eval
2007 Jan 17
1
Coefficient of determination when intercept is zero
I am curious as to the "lm" calculation of R2 (multiple coefficient of
determination, I assume) when intercept is zero. I have 18 data points, two
independent variables:
First, a model with an intercept:
> mod0=lm(Div~Rain+Evap,data=test)
> summary(mod0)$r.squared
[1] 0.6257541
> cor(predict(mod0),test$Div)^2
[1] 0.6257541
The $r.squared and the result from "cor" are the same, as I would expect.
Now we try a model with zero intercept:
> mod1=lm(Div~0+Rain+Evap,data=test)
> summary(mod1)$r.squared...
2010 Sep 15
1
Difficulty creating Julian day in data frame
...g to add a "Julian Day" column to a data frame.
Here is my code and the resulting data frame:
vic.data <- read.table("C:/VIC/data/vic.data.csv", header=F)
names(vic.data) <- c("year", "month", "day", "precip", "evap",
"runoff", "baseflow", "Tsup", "SM1", "SM2", "SM3", "SWE")
vic.data$temp.date <- as.Date(paste(vic.data$year, "/",
vic.data$month, "/", vic.data$day, sep=""))
vic.data$ju...