Combine two data frames and remove duplicate columns

Question

I want to cbind two data frames and remove duplicated columns. For example:

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df1 <- data.frame(var1=c('a','b','c'), var2=c(1,2,3))
df2 <- data.frame(var1=c('a','b','c'), var3=c(2,4,6))

cbind(df1,df2) #this creates a data frame in which column var1 is duplicated

I want to create a data frame with columns var1, var2 and var3, in which column var2 is not repeated.

Answer 1

merge will do that work.

try:

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merge(df1, df2)

Answer 2

In case you inherit someone else's dataset and end up with duplicate columns somehow and want to deal with them, this is a nice way to do it:

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for (name in unique(names(testframe))) {
  if (length(which(names(testframe)==name)) > 1) {
    ## Deal with duplicates here. In this example
    ## just print name and column #s of duplicates:
    print(name)
    print(which(names(testframe)==name))
  }
}