R: Revalue multiple special characters in a data.frame
That seems pretty straight forward to me. I'm pretty new too but in general I'm not sure if you can get better than one command. Though you could have combined all that:

&gt; newValueVector &lt;- c("+"="5", "?"="2", "K"="3", "k"="3")
&gt; data$Multiplier &lt;-  revalue(data$Multiplier, newValueVector)