SAGA-GIS Tool Library Documentation (v6.1.0)

Tool Grid Calculator

The Grid Calculator calculates a new grid based on existing grids and a mathematical formula. The grid variables in the formula begin with the letter 'g' followed by a position index, which corresponds to the order of the grids in the input grid list (i.e.: g1, g2, g3, ... correspond to the first, second, third, ... grid in list). Grids from other systems than the default one can be addressed likewise using the letter 'h' (h1, h2, h3, ...), which correspond to the 'Grids from different Systems' list.

Example: sin(g1) * g2 + 2 * h1

The following operators are available for the formula definition:

+Addition
-Subtraction
*Multiplication
/Division
abs(x)Absolute Value
mod(x, y)Returns the floating point remainder of x/y
int(x)Returns the integer part of floating point value x
sqr(x)Square
sqrt(x)Square Root
exp(x)Exponential
pow(x, y)Returns x raised to the power of y
x ^ yReturns x raised to the power of y
ln(x)Natural Logarithm
log(x)Base 10 Logarithm
pi()Returns the value of Pi
sin(x)Sine
cos(x)Cosine
tan(x)Tangent
asin(x)Arcsine
acos(x)Arccosine
atan(x)Arctangent
atan2(x, y)Arctangent of x/y
min(x, y)Returns the minimum of values x and y
max(x, y)Returns the maximum of values x and y
gt(x, y)Returns true (1), if x is greater than y, else false (0)
x > yReturns true (1), if x is greater than y, else false (0)
lt(x, y)Returns true (1), if x is less than y, else false (0)
x < yReturns true (1), if x is less than y, else false (0)
eq(x, y)Returns true (1), if x equals y, else false (0)
x = yReturns true (1), if x equals y, else false (0)
and(x, y)Returns true (1), if both x and y are true (i.e. not 0)
or(x, y)Returns true (1), if at least one of both x and y is true (i.e. not 0)
ifelse(c, x, y)Returns x, if condition c is true (i.e. not 0), else y
rand_u(x, y)Random number, uniform distribution with minimum x and maximum y
rand_g(x, y)Random number, Gaussian distribution with mean x and standard deviation y
xpos(), ypos()Get the x/y coordinates for the current cell
col(), row()Get the current cell's column/row index
ncols(), nrows()Get the number of columns/rows
nodata()Returns resulting grid's no-data value

Parameters

 NameTypeIdentifierDescriptionConstraints
InputGrids (*)Grid list (optional input)GRIDSin the formula these grids are addressed in order of the list as 'g1, g2, g3, ...'-
Grids from different Systems (*)Grid list (optional input)XGRIDSin the formula these grids are addressed in order of the list as 'h1, h2, h3, ...'-
OutputResultGrid (output)RESULT--
OptionsGrid systemGrid systemPARAMETERS_GRID_SYSTEM--
ResamplingChoiceRESAMPLING-Available Choices:
[0] Nearest Neighbour
[1] Bilinear Interpolation
[2] Bicubic Spline Interpolation
[3] B-Spline Interpolation
Default: 3
FormulaTextFORMULA-Default: (g1 - g2) / (g1 + g2)
NameTextNAME-Default: Calculation
Take FormulaBooleanFNAME-Default: 0
Use NoDataBooleanUSE_NODATACheck this in order to include no-data cells in the calculation.Default: 0
Data TypeChoiceTYPE-Available Choices:
[0] bit
[1] unsigned 1 byte integer
[2] signed 1 byte integer
[3] unsigned 2 byte integer
[4] signed 2 byte integer
[5] unsigned 4 byte integer
[6] signed 4 byte integer
[7] 4 byte floating point number
[8] 8 byte floating point number
Default: 7
(*) optional

Command-line

Usage: saga_cmd grid_calculus 1 [-GRIDS <str>] [-XGRIDS <str>] [-RESAMPLING <str>] [-RESULT <str>] [-FORMULA <str>] [-NAME <str>] [-FNAME <str>] [-USE_NODATA <str>] [-TYPE <str>]
  -GRIDS:<str>     	Grids
	Grid list (optional input)
  -XGRIDS:<str>    	Grids from different Systems
	Grid list (optional input)
  -RESAMPLING:<str>	Resampling
	Choice
	Available Choices:
	[0] Nearest Neighbour
	[1] Bilinear Interpolation
	[2] Bicubic Spline Interpolation
	[3] B-Spline Interpolation
	Default: 3
  -RESULT:<str>    	Result
	Grid (output)
  -FORMULA:<str>   	Formula
	Text
	Default: (g1 - g2) / (g1 + g2)
  -NAME:<str>      	Name
	Text
	Default: Calculation
  -FNAME:<str>     	Take Formula
	Boolean
	Default: 0
  -USE_NODATA:<str>	Use NoData
	Boolean
	Default: 0
  -TYPE:<str>      	Data Type
	Choice
	Available Choices:
	[0] bit
	[1] unsigned 1 byte integer
	[2] signed 1 byte integer
	[3] unsigned 2 byte integer
	[4] signed 2 byte integer
	[5] unsigned 4 byte integer
	[6] signed 4 byte integer
	[7] 4 byte floating point number
	[8] 8 byte floating point number
	Default: 7