R - change alpha value of individual lines in ggsurvplot

Question

This is my first question in stack overflow so please bear with me. I am trying to change the alpha of the individual lines in my ggsurvplot but i'm not quite sure if this is possible. I allready found some websites (e.g. http://www.rpubs.com/Mentors_Ubiqum/Transparent_Lines and http://www.sthda.com/english/wiki/print.php?id=177) but these codes don't seem to work for ggsurvplot.

ggsurvplot(fit, data=ND,
           conf.int = FALSE,
           ggtheme = theme_classic(base_size = 13, base_line_size = 0.4, base_rect_size = 0.8),
           size = 2,
           palette=c("palevioletred1", "darkslategray1", "gold1", "palegreen3", "purple2","Dodgerblue1", "darkorange1","mediumseagreen"),
           alpha = c(0.2, 0.2, 0.2, 1, 0.2, 0.2, 0.2, 1),
           # censor= FALSE,
           censor.size=2,
           # censor.shape = c(124),

           legend="right", 
           legend.labs =c("I-PET1 neg", "I-PET2 neg", "I-PET3 neg", "I-PET4 neg", "I-PET1 pos", "I-PET2 pos", "I-PET3 pos", "I-PET4 pos"),
           legend.title = " ",
           xlab = "Time (months)",
           break.time.by = 12

)

Anyone knows how to do this? Furthermore, the values on the x and y axes are grey and I would like them to be black. Any suggestions on that?

Many thanks!

user_12258459 · Answer

not all of us is familiar with the type of data you are handling. For example, we would not know what is in "fit", and why you called the various parameters etc. Hence @teunbrand ask you to provide more information, and others can provide more help.

There is no alpha option inside ggsurvplot. The easiest solution is to add the alpha to the colours you specified, using alpha function in ggplot2. See below for an example:

library("survminer")
library(gridExtra)
require("survival")
fit <- survfit(Surv(time, status) ~ sex, data = lung)

g1 = ggsurvplot(fit,
           conf.int = FALSE,
           palette=c("gold1", "palegreen3"),
           title="no alpha"
)
g2 = ggsurvplot(fit,
           conf.int = FALSE,
           palette=alpha(c("gold1", "palegreen3"),c(0.7,0.3)),
           title="alpha_0.7_0.3"
)
grid.arrange(g1$plot,g2$plot,ncol=2)

R - change alpha value of individual lines in ggsurvplot

1 Answers