paste(), gsub(), grep(), substr()

# Concatenate
paste("Gobio", "gobio")              # "Gobio gobio" (space sep)
paste0("sample_", 1:3)               # "sample_1" "sample_2" "sample_3"
paste(c("a","b","c"), collapse = "-") # "a-b-c"

# Case
toupper("hello"); tolower("WORLD")

# Pattern matching
x <- c("Gobio gobio", "Cottus sp.", "Leuciscus leuciscus")
grep("gobio", x)           # index: 1
grepl("gobio", x)          # logical: TRUE FALSE FALSE
grep("gobio", x, value = TRUE)

# Replace
gsub("_", " ", "Gobio_gobio")         # "Gobio gobio"
sub("^(\\w+).*", "\\1", x)            # extract genus

# Split / extract
strsplit("Gobio gobio", " ")[[1]]     # "Gobio" "gobio"
substr("Gobio gobio", 1, 5)           # "Gobio"
nchar(x)                              # string lengths