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# Create a scatter plot matrix in Scilab

## Abstract

In this page, we present a function to create a scatter plot matrix in Scilab.

## Introduction

According to NIST , "given a set of variables X1, X2, ... , Xk, the scatter plot matrix contains all the pairwise scatter plots of the variables on a single page in a matrix format. That is, if there are k variables, the scatter plot matrix will have k rows and k columns and the ith row and jth column of this matrix is a plot of Xi versus Xj."

This feature is available from the "plotmatrix" function in Stixbox, v2.2. To install it, please use

`atomsInstall('stixbox')`

and restart Scilab.

The scripts are also available in attachement :

## Scatter plot matrix

The function scattermatrix creates a scatter plot matrix. It has the calling sequence:

`scattermatrix(x)`

where x is a n-by-ninput matrix of doubles. Here, ninput is the number of input parameters and n is the number of experiments.

Here is the simplest example of scattermatrix. We have a model with 3 inputs and 3 outputs. We are interested in the scatter plot matrix of the outputs y1, y2, y3.

```    m=1000;
x1=grand(m,1,"def");
x2=grand(m,1,"def");
x3=grand(m,1,"def");
y1=2*x1.*x2+x3;
y2=-3*x1+x2.^2-2*x3;
y3=sin(x1)-3*x2+3*x3;
y=[y1,y2,y3];
//
ylabels=["Y1","Y2","Y3"];
// No labels
scattermatrix(y);``` It is straightforward to add labels:

```    // With labels
scattermatrix(y,"xlabels",ylabels);``` We can also replace the empty diagonal with an histogram.

```    // With the histogram
scattermatrix(y,"histogram",%t);``` ## Scatter matrix X vs Y

The function scattermatrixXY plots the dependencies between Y and X in a model.

The script:

```    m=1000;
x1=grand(m,1,"def");
x2=grand(m,1,"def");
x3=grand(m,1,"def");
y1=2*x1.*x2+x3;
y2=-3*x1+x2.^2-2*x3;
y3=sin(x1)-3*x2+3*x3;
x=[x1,x2,x3];
y=[y1,y2,y3];
//
xlabels=["X1","X2","X3"];
ylabels=["Y1","Y2","Y3"];
// No labels
scattermatrixXY(x,y);```

produces: This is perhaps clearer with labels.

```    // With labels
scattermatrixXY(x,y,"xlabels",xlabels,"ylabels",ylabels);``` We can customize various settings, including the labels, the dot symbol and the size of the point.    Author: Michaël Baudin, 2013

2022-09-08 09:27