# 2.2.27 subtract_line

## Contents

Analysis: Data Manipulation: Subtract Straight Line

## Brief Information

Subtract straight line from a data plot

## Command Line Usage

 subtract_line x1:=0 y1:=0.5 x2:=200 y2:=3.5; 

## Variables

Display
Name
Variable
Name
I/O
and
Type
Default
Value
Description
Input iy

Input

XYRange

<active>

Specifies the input data that will be subtracted.

X1 x1

Input

double

0

Specifies the X value of the first point.

Y1 y1

Input

double

0

Specifies the Y value of the first point.

X2 x2

Input

double

<unassigned>

Specifies the X value of the second point.

Y2 y2

Input

double

<unassigned>

Specifies the Y value of the second point.

Output oy

Output

XYRange

<input>

Specifies the output range for the subtracted data.

See the syntax here.

## Description

This X-Function can be used to subtract a straight line from a data set. The straight line is determined by two points. If you use this X-Function from the menu and a graph is active, you can click on the graph to select these two points. If you use this X-Function from script, you can specify the X and Y values of these two points.

## Examples

• Code Sample
// In this example of the subtract_line X-Function, we will subtract a straight line created by the endpoints of a curve
// Import our sample dataset
newbook;
path$= system.path.program$ + "Samples\Spectroscopy\Raman Baseline.dat";
impasc fname:=path\$;
// define ranges for X and Y and an XY range
range rx = 1;
range ry = 2;
range rxy = (1,2);
range rxynew = (3,4); // columns do not exist yet
// Plot our data
plotxy rxy plot:=201 color:=color(blue);

// Use the X and Y ranges to get the endpoints and subtract into new columns and plot
subtract_line iy:=rxy x1:=rx y1:=ry x2:=rx[rx.nrows] y2:=ry[ry.nrows] oy:=<new>;
plotxy rxynew color:=color(orange) plot:=201 ogl:=1;

// Add the line used for subtraction - before and after subtracting
draw -n subline1 -l {rx,ry,rx[rx.nrows],ry[ry.nrows]};
subline1.color=2;
draw -n subline2 -l {rx,0,rx[rx.nrows],0};
subline2.color=1;

## Related X-Functions

Keywords:baseline correction, subtraction