trend lines for log plots

[jsfenfen]

On mouseover should display 7-day trend line, this is it in R

# Assume a csv with headers "Cases" and "day", the latter starting at 1
# and read it into data
data <- read.csv(datafile)
# eyeball it on a linear scale to see if it looks right
plot(data$day,data$Cases)
# linear regression on base 2 log of cases vs days, 22-26 observations only
fit <- lm( data[22:26,"day"] ~ log2(data[22:26,"Cases"]) )
# spit out the doubling time in days
fit$coef[2]