Monthly Copiktra scripts vs. geometric progression

#
# An R script to visually compare the monthly growth trajectory of medical scripts
# for Verastem's Copiktra to a given geometric progression (a Compounded Monthly Growth Rate)
#
# (c) 2019 Germain Garand <germain.garand@laposte.net>
#
# This is for information purposes only. Any calculation performed herein could be
# wrong and/or misrepresent reality. Use at your own risk.
#
# License: Creative Commons BY-NC 2.0
#
# Version 0.02
#
# History:
#   0.01 - 2019/11/26- .initial version
#   0.02 - .fix geometric progression starting at n+1 instead of n (^0)
#          .fix ylim of geometric plot (must take max of a, not the tail)
#          .round geometric values on axis for prettier display
#

# common ratio of the geometric progression to use as comparator
geom_ratio <- 1.18

# Monthly Copiktra scripts data (insto+retail)
###  Not sure how trustable those informations are. Please double check!
a <- c(18, 33, 61, 69, 52, 71, 76, 94, 89, 116, 118, 157, 132)
c <- c(1:length(a))
b <- 18*geom_ratio**(0:(length(a)-1))

message("Geometric progression: ", paste(round(b), " "))

e <- data.frame(c,a,b)
names(e) <- c("Month", "Scripts", "Geometric")

p <- (geom_ratio-1)*100

png("copiktra_scripts.png", width=480, height=480)
plot(Scripts ~ Month, e, type = 'l', col='blue', main=paste("Copiktra scripts vs.", geom_ratio, "(",p,
     "% CMGR) Geometric progression", sep=''), ylab="Scripts")
par(new=TRUE)
plot(Geometric ~ Month, e, type='l', ylim=c(head(a,1),max(a)),axes=FALSE, ann=FALSE,col='violet')
axis(4, round(e$Geometric), col='violet', col.axis='violet')
legend("top", inset=.05, c("Copiktra scripts","Geometric reference"), fill=c("blue","violet"))
dev.off()