# Get libraries
library(data.table)
library(ggplot2)

# Data table for demo
data <- data.table("Bad names" = 1:100, "Shouldn't use spaces" = rep(c("text","other"),100))

# Store the original names
# Changing this to c(names(data)) solves the problem but is a hack
original.names <- names(data)

# Update the data's column names
setnames(data, old = names(data),new = c("V1","V2"))

# Now original.names has also been changed to the new names
# However, only the names of the data should have changed.
cat(original.names,"n", names(data))

# Random ggplot
ggplot(data) + geom_bar(aes(V1))

# Rename data
setnames(data, names(data), original.names)

# I still get names V1 and V2, it is as if original names has been changed globally.
cat(names(data))