[Gretl-users] plot with --band option, revisited

Last month I announced the existence of a --band option for the "gnuplot" and "plot" commands -- see http://lists.wfu.edu/pipermail/gretl-users/2016-May/011846.html Since then, Jack and I have considered this more carefully, and the next gretl release (due out within a week) will incorporate a modified version of this option. The new version is more functional than the previous one, and moreover it is designed to allow future extensions in case we decide it's worth supporting more complex variants. So here's the current situation: the "band" information is spread across two options, --band and --band-style. The syntax is as follows: (1) --band wants either 2 or 3 comma-separated arguments: the "center" of the band (which may or may not be plotted in its own right), the "width" of the band (e.g. a series holding standard errors) and, optionally, a multiplier (e.g., number of standard errors). If the third argument is omitted it defaults to 1.0. So suppose you have series yhat and se_yhat and you'd like to plot yhat along with a band at yhat plus-and-minus 1.96 se_yhat; then the option would be --band=yhat,se_yhat,1.96 However, if your second series is already expressed as suitable multiples of standard errors (call it "maxerr") you could do: --band=yhat,maxerr (2) --band-style wants either 1 or 2 arguments (comma-separated if you give two). The first may be either "line", "dash" or "fill", to represent the band by enclosing lines or dashes, or by a shaded area. The default, if this argument is omitted, is "line". The second is a hexadecimal RGB color specification: for example 0xff0000 means red. Examples: --band-style=fill # shaded area using default color --band-style=dash,0x0000ff # blue dashes --band-style=0xdddddd # grey lines If you want the center of the band to be plotted in its own right you should give that as an argument to the "gnuplot" command. Here's a simple example: gnuplot yhat --band=yhat,se_yhat,2 --with-lines This mechanism also works with the "plot" command-block: list P = yhat # add more series if you like plot P options band=yhat,se_yhat,2 band-style=0xdddddd option with-lines end plot --output=display It also works when plotting columns of a matrix. However, in this case the columns to be plotted in their own right are given in one named matrix and the (center,width) of the band are given in a second named matrix with two columns. Example: matrix MP = {yhat} # plot more columns if you wish matrix B = {yhat,se_yhat} plot MP options band=B,1.96 band-style=0xdddddd option with-lines end plot --output=display Allin Cottrell