R Data Analysis Cookbook, Second Edition - Second Edition

Handling column headers/variable names

If your data file does not have column headers, set header=FALSE.

The auto-mpg-noheader.csv file does not include a header row. The first command in the following snippet reads this file. In this case, R assigns default variable names V1, V2, and so on.

> auto  <- read.csv("auto-mpg-noheader.csv", header=FALSE) > head(auto,2)    V1 V2 V3  V4 V5   V6   V7 V8                  V9 1  1 28  4 140 90 2264 15.5 71 chevrolet vega 2300 2  2 19  3  70 97 2330 13.5 72     mazda rx2 coupe 

If your file does not have a header row, and you omit the header=FALSE optional argument, the read.csv() function uses the first row for variable names and ends up constructing variable names by adding X to the actual data values in the first row. Note the meaningless ...