plotting 4 variables graph from csv file

Question

I have a csv file with 4 columns like this:

P Q R cost

6, 3, 1, SC

6, 2, 2, SC

6, 1, 3, SC

5, 4, 1,

5, 3, 2,

5, 2, 3, DR

5, 1, 4, DR

4, 5, 1, DR

4, 4, 2, BR

4, 3, 3, BR

The first three columns are showing all the possible partitions of a number (n) between three variables (P, Q, R). In this example (n=10) and I didn't show all the possible combination. The last column shows that for each ratio which case is best (SC, BR or DR). My idea to plot is to use Q on the x-axis and R on the y-axis and plot area where BR or SC or DR is best. Can any expert please help me? I provided the sample csv file data for the minimum example.

Answer 1

I still don't know if this is anything like what you had in mind. If not, do consider making a sketch.

\documentclass[border=5mm]{standalone}
\usepackage{pgfplotstable}
\pgfplotsset{compat=1.17}
% Note commas in the header as well!
\pgfplotstableread[col sep=comma]{
P, Q, R, cost
6, 3, 1, SC
6, 2, 2, SC
6, 1, 3, SC
5, 4, 1, DR
5, 3, 2, BR
5, 2, 3, DR
5, 1, 4, DR
4, 5, 1, DR
4, 4, 2, BR
4, 3, 3, BR
}\MyData

% you'll have the data in a file, so do
% \pgfplotstableread[col sep=comma]{filename}
% instead of the above
\begin{document}
\begin{tikzpicture}
% define a few macros for convenience
\newcommand\AxisW{6cm} % width/height of axis
\newcommand\AxisXMin{0.5} % xmin/ymin
\newcommand\AxisRange{10} % range of axis, both x and y
\begin{axis}[
  % define how the different cases are drawn
  % all should have same mark and draw opacity,
  % but change the color as you prefer
  scatter/classes={
    SC={mark=square*, draw opacity=0, fill=blue},
    DR={mark=square*, draw opacity=0, fill=red},
    BR={mark=square*, draw opacity=0, fill=green}
 },
 % add labels for the axes
 xlabel=Q,
 ylabel=R,
 % set up the size of the axis
 scale only axis, % width/height applies to axis box alone, without labels
 width=\AxisW, height=\AxisW,
 % set up the range of the axes
 xmin=\AxisXMin, xmax=\AxisXMin+\AxisRange,
 ymin=\AxisXMin, ymax=\AxisXMin+\AxisRange,
 % calculate the mark size - divide by 2 because the size is half the width
 mark size={\AxisW/\AxisRange/2},
 % set legend entries in one row
 legend columns=-1,
 % move legend outside top of axis
 legend style={at={(0.5,1.02)}, anchor=south},
 % have ticks every 1 unit distance
 xtick distance=1,ytick distance=1,
 ] 

\addplot [
  scatter, % make a scatter plot
  only marks, % for some reason have to say that we only want markers
  scatter src=explicit symbolic % say that the variable that declares which scatter class a point belongs to is explicitly given in the data stream, and is not a number, so should not be parsed as a number
  ]
  table[x=Q, % use Q-column for x-values
        y=R, % use R-column for y-values
        meta=cost % use cost-column to define which scatter class should be used
        ] \MyData;

\legend{SC, DR, BR}
\end{axis}
\end{tikzpicture}
\end{document}