QgsMeshCalculator class

Performs mesh layer calculations.

Contents

Mesh calculator can do various mathematical operations between dataset groups from a single mesh layer. Resulting dataset group is added to the mesh layer. Result can be filtered by extent or a vector layer mask spatially and by selection of times.

Note: only dataset groups defined on vertices are implemented and supported

Public types

enum Result { Success = 0, Canceled, CreateOutputError, InputLayerError, ParserError, InvalidDatasets, EvaluateError, MemoryError }
Result of the calculation.

Public static functions

static auto expression_valid(const QString& formulaString, QgsMeshLayer* layer) -> Result
Returns whether formula is valid for particular mesh layer.

Constructors, destructors, conversion operators

QgsMeshCalculator(const QString& formulaString, const QString& outputFile, const QgsRectangle& outputExtent, double startTime, double endTime, QgsMeshLayer* layer)
Creates calculator with bounding box (rectangular) mask.
QgsMeshCalculator(const QString& formulaString, const QString& outputFile, const QgsGeometry& outputMask, double startTime, double endTime, QgsMeshLayer* layer)
Creates calculator with geometry mask.

Public functions

auto processCalculation(QgsFeedback* feedback = nullptr) -> Result
Starts the calculation, writes new dataset group to file and adds it to the mesh layer.

Enum documentation

enum QgsMeshCalculator::Result

Result of the calculation.

Enumerators
Success

Calculation successful.
Canceled

Calculation canceled.
CreateOutputError

Error creating output data file.
InputLayerError

Error reading input layer.
ParserError

Error parsing formula.
InvalidDatasets

Datasets with different time outputs or not part of the mesh.
EvaluateError

Error during evaluation.
MemoryError

Error allocating memory for result.

Function documentation

static Result QgsMeshCalculator::expression_valid(const QString& formulaString, QgsMeshLayer* layer)

Returns whether formula is valid for particular mesh layer.

Parameters
formulaString formula/expression to evaluate. Consists of dataset group names, operators and numbers
layer mesh layer with dataset groups references in formulaString
Returns QgsMeshCalculator::Success in case of success

QgsMeshCalculator::QgsMeshCalculator(const QString& formulaString, const QString& outputFile, const QgsRectangle& outputExtent, double startTime, double endTime, QgsMeshLayer* layer)

Creates calculator with bounding box (rectangular) mask.

Parameters
formulaString formula/expression to evaluate. Consists of dataset group names, operators and numbers
outputFile file to store the resulting dataset group data
outputExtent spatial filter defined by rectangle
startTime time filter defining the starting dataset
endTime time filter defining the ending dataset
layer mesh layer with dataset groups references in formulaString

QgsMeshCalculator::QgsMeshCalculator(const QString& formulaString, const QString& outputFile, const QgsGeometry& outputMask, double startTime, double endTime, QgsMeshLayer* layer)

Creates calculator with geometry mask.

Parameters
formulaString formula/expression to evaluate. Consists of dataset group names, operators and numbers
outputFile file to store the resulting dataset group data
outputMask spatial filter defined by geometry
startTime time filter defining the starting dataset
endTime time filter defining the ending dataset
layer mesh layer with dataset groups references in formulaString

Result QgsMeshCalculator::processCalculation(QgsFeedback* feedback = nullptr)

Starts the calculation, writes new dataset group to file and adds it to the mesh layer.

Parameters
feedback The optional feedback argument for progress reporting and cancelation support
Returns QgsMeshCalculator::Success in case of success