What is trace in R's heatmap.2 function?

Question

[NHEJ]

Very simply, what is the best way to understand what the trace feature represents (which adds a line to the middle of each column when drawing a heatmap) of heatmap.2 in R? There's practically nothing online about this (yet).

[Devon Ryan]

Off-topic, but I really wish the trace parameter defaulted to "none".

[David W]

The first step to understanding a function's behaviour is to read the documentation. Have you done ?heatmap.2

[NHEJ]

Of course..

[David W]

And what about the documentation do you not understand?

Answer 1

[Ying W]

Since nobody is posting...

trace

character string indicating whether a solid "trace" line should be drawn across 'row's or down 'column's, 'both' or 'none'. The distance of the line from the center of each color-cell is proportional to the size of the measurement. Defaults to 'column'.

http://www.inside-r.org/packages/cran/gplots/docs/heatmap.2

[russhh]

well, nobody posted that, because OP has stated that they've read that.