Tilapia<-5
Mystus_singaringan<-c(1,2,2,2)
Osteochilus_vittatus<-c(26,30,11,2,28,6,19,12,4,4,18,13,29,21,9,8,21,19,28)
Henicorhynchus_siamensis<-c(46,22,33,28,50,42,31,4,13,8,11,8,18)
names<-c("Tilapia","Mystus","Osteochilus","Henicorhynchus")
wize<- lengths(list(Tilapia,Mystus_singaringan,Osteochilus_vittatus,Henicorhynchus_siamensis))
fishnames<-c(rep(names,wize))
metacercaria<-c(Tilapia,Mystus_singaringan,Osteochilus_vittatus,Henicorhynchus_siamensis)
df<- data.frame(fishnames,metacercaria)
head(df)
Now use tapply to summarise things for each species, for example, the mean for each species
tapply(df$metacercaria,df$fishnames,mean)
tapply(df$metacercaria,df$fishnames,range)