Set comparison mode off (compare off, the default), or on (compare on), or delta (compare delta) or ratio (compare ratio). If comparison mode is off, when multiple experiments are read the data is aggregated. If comparison is enabled, when multiple experiments are loaded separate columns of metrics are shown for the data from each experiment. If comparison mode is delta, the base experiment shows absolute metrics but the comparison experiment shows differences between it and the base. If comparison mode is ratio, the comparison experiment shows ratios between it and the base.
Comparison mode will treat each experiment or experiment-group as a separate compare group. The first experiment or experiment-group argument is the base group. If you want to include more than one experiment in a compare group, you must create an experiment-group file to use as a single argument to er_print.