title: if else statement in data.table package
body: <p>I have a dataset of 6 column and 4.5 millions rows. I would like to write a logical check if in the fifth column there are values with zeroes, to put 1 in the sixth column. Could you explain me how to construct an algorithm to do this? In the fifth column I found that I have cells with zero value. I want to perform if in the fifth column I have zero values to put 1 in sixth column and if not to put 0? I must use data.table package. I try with this 
  name of the data[,6] = ifelse(name of the data[,5] == 0, 1, name of the data[,6]).</p>