I have a table with 200 columns, and each column has negative values randomly populated. In some columns-like temperature- negative value is meaningful while performing summary statistics, but in others it is a filler for either "data not recorded- communication error" or "data not available- Equipment shut off". When I want to plot, the negative values are useful. So my Q is how do I keep the negative values for plotting, while I am disregarding them while doing summary statistics? What are the different ways to approach this?