Classification using expression

Use expressions to calculate properties of individual classes in a category.

The last Expression can be TRUE which will imply that the last expression will always be assigned if all above evaluates as false

Parameters

Expression

NOTE

The expressions are applied in order top-down

Choose a new class and write the expression for it.

Click the “Add” button to add additional classification expressions. Click the color square to select color for the classification class.

The operators that can be used:

Operators than can be used expressions include the data operators wNNN and bMMM for referring to wavelength bands, the range operator : used for averaging data, standard arithmetic (+,-,/,* …) and comparison operators (=,>,< …) as well as some mathematical functions (…) and constants ().

Breeze does not validate the provided expression until you click Apply changes to apply it to some data.

Data Operator

Description

wNNN

Wavelength lookup operator that finds the wavelength band closest to the provided number NNN. This means NNN need not match exactly to find data.

A setting controls how far off a wavelength is allowed to be to be considered a match. If there isn’t matching data an error is displayed when applying the workflow to data. Learn more in Wavelength matching.

Example of this syntax: w700 or w1714.

bMMM

Band index operator. MMM represent the one-based index of a wavelength band. For example b1 is the first band, and b20 is the twentieth.

If the index MMM does not exist, Breeze displays an error message.

:

Average range operator that returns the average value for a range of wavelength bands.

For example: w1200:w1500 yields average value of all data points between wavelength 1200 nm and 1500 nm. b1:b2 yields average values of the first two bands.

Expand to see all available operators

Arithmetic Operator	Description
`-`	Subtract
`+`	Add
`/`	Divide
`*`	Multiply
`%`	Modulo
`^`	Raised to a power

Comparison Operator	Description
`=`	Equal to
`\|` `OR`	TRUE if any of the conditions separated by OR is TRUE
`&` `AND`	TRUE if all the conditions separated by AND is TRUE
`!=` `<>`	Not equal to
`<`	Less than
`<=`	Less than or equal to
`>`	Greater than
`>=`	Greater than or equal to

Function operator	Description
`SQRT(N)`
`SIN(N)`
`COS(N)`
`EXP(N)`
`LOG(N)`
`LOG10(N)`
`AVG(N)`
`ROUND(N)`

Constants	Description
`TRUE`	Always evaluates to TRUE
`FALSE`	Always evaluates to FALSE
`INF`	token value
`PI`	approximated to

The parameters that can be used:

Area
Length
Width
Circumference
Regularity
Roundness
Angle
D1
D2
X
Y
MaxBorderDistance
BoundingBoxArea

For details on each available property see: Object properties Details

Pretreatments

In top-down applied order ⬇️ , meaning Savitzky-Golay is applied first then Derivative and so on.

Savitzky-Golay
Derivative
SNV (Standard Normal Variate)
Logarithm
Center
UV (Unit Variance) scaling

For more on each type of pretreatment see: Pretreatments