Class: QgsRasterBlock¶

Raster data container.

Methods

`applyNoDataValues`
`applyScaleOffset`	Apply band scale and offset to raster block values
`as_numpy`	Returns the block data as a numpy array.
`color`	Read a single color
`convert`	Convert data to different type.
`data`	Gets access to raw data.
`dataType`	Returns data type
`dataTypeSize`	Data type size in bytes.
`error`	Returns the last error
`hasNoData`	Returns `True` if the block may contain no data.
`hasNoDataValue`	`True` if the block has no data value.
`height`	Returns the height (number of rows) of the raster block.
`image`	Returns an image containing the block data, if the block's data type is color.
`isEmpty`	Returns `True` if block is empty, i.e. its size is 0 (zero rows or cols).
`isNoData`	Checks if value at position is no data
`isValid`	Returns `True` if the block is valid (correctly filled with data).
`noDataValue`	Returns no data value.
`reset`	Reset block
`resetNoDataValue`	Reset no data value: if there was a no data value previously set, it will be discarded.
`setColor`	Set color on position
`setData`	Rewrite raw pixel data.
`setError`	Sets the last error
`setImage`	Sets the block data via an image.
`setIsData`	Remove no data flag on pixel.
`setIsNoData`	Set no data on pixel
`setIsNoDataExcept`	Set the whole block to no data except specified rectangle
`setNoDataValue`	Sets cell value that will be considered as "no data".
`setValid`	Mark block as valid or invalid
`setValue`	Set value on position
`toString`
`value`	Read a single value if type of block is numeric.
`width`	Returns the width (number of columns) of the raster block.

Static Methods

`printValue`	Print double value with all necessary significant digits.
`subRect`	For extent and width, height find rectangle covered by subextent.
`typeIsColor`	Returns `True` if data type is color
`typeIsNumeric`	Returns `True` if data type is numeric
`typeSize`	Returns the size in bytes for the specified dataType.
`typeWithNoDataValue`	For given data type returns wider type and sets no data value
`valueBytes`	Gets byte array representing a value.

class qgis.core.QgsRasterBlock[source]¶

Bases: object

__init__()

__init__(dataType: Qgis.DataType, width: int, height: int)

Constructor which allocates data block in memory

Parameters:

dataType (Qgis.DataType) – raster data type
width (int) – width of data matrix
height (int) – height of data matrix

__init__(a0: QgsRasterBlock)

Parameters:: a0 (QgsRasterBlock)

applyNoDataValues(self, rangeList: Iterable[QgsRasterRange])[source]¶

Parameters:: rangeList (Iterable[QgsRasterRange])

applyScaleOffset(self, scale: float, offset: float)[source]¶

Apply band scale and offset to raster block values

Parameters:

scale (float)
offset (float)

as_numpy(use_masking: bool = True) → ndarray | MaskedArray¶

Returns the block data as a numpy array.

If use_masking is True then the returned array will be a numpy masked array, masking the raster block’s nodata values.

Raises:: QgsNotSupportedException – if numpy is not available on the system

Added in version 3.40.

color(self, row: int, column: int) → int[source]¶

Read a single color

Parameters:

row (int) – row index
column (int) – column index

Return type:

int

Returns:

color

color(self, index: int) → int[source]

Read a single value

Parameters:: index (int) – data matrix index (long type in Python)
Return type:: int
Returns:: color

convert(self, destDataType: Qgis.DataType) → bool[source]¶

Convert data to different type.

Parameters:: destDataType (Qgis.DataType) – dest data type
Return type:: bool
Returns:: True on success

data(self) → QByteArray[source]¶

Gets access to raw data. The returned QByteArray instance is not a copy of the data: it only refers to the array owned by the QgsRasterBlock, therefore it is only valid while the QgsRasterBlock object still exists. Writing to the returned QByteArray will not affect the original data: a deep copy of the data will be made and only the local copy will be modified.

Note

in Python the method returns ordinary bytes object as the

Return type:: QByteArray

dataType(self) → Qgis.DataType[source]¶

Returns data type

Return type:: Qgis.DataType

dataTypeSize(self) → int[source]¶

Data type size in bytes.

Return type:: int

error(self) → QgsError[source]¶

Returns the last error

Return type:: QgsError

hasNoData(self) → bool[source]¶

Returns True if the block may contain no data. It does not guarantee that it really contains any no data. It can be used to speed up processing. Not the difference between this method and hasNoDataValue().

Return type:: bool
Returns:: True if the block may contain no data

hasNoDataValue(self) → bool[source]¶

True if the block has no data value.

Return type:: bool
Returns:: True if the block has no data value

See also

noDataValue()

See also

setNoDataValue()

See also

resetNoDataValue()

height(self) → int[source]¶

Returns the height (number of rows) of the raster block.

See also

width()

Return type:: int

image(self) → QImage[source]¶

Returns an image containing the block data, if the block’s data type is color.

Return type:: QImage

isEmpty(self) → bool[source]¶

Returns True if block is empty, i.e. its size is 0 (zero rows or cols). This method does not return True if size is not zero and all values are ‘no data’ (null).

Return type:: bool

isNoData(self, row: int, column: int) → bool[source]¶

Checks if value at position is no data

Parameters:

row (int) – row index
column (int) – column index

Return type:

bool

Returns:

True if value is no data

See also

valueAndNoData()

isNoData(self, row: int, column: int) → bool[source]

Check if value at position is no data

Parameters:

row (int) – row index
column (int) – column index

Return type:

bool

Returns:

True if value is no data

See also

valueAndNoData()

isNoData(self, index: int) → bool[source]

Check if value at position is no data

Parameters:: index (int) – data matrix index (long type in Python)
Return type:: bool
Returns:: True if value is no data

See also

valueAndNoData()

isValid(self) → bool[source]¶

Returns True if the block is valid (correctly filled with data). An empty block may still be valid (if zero size block was requested). If the block is not valid, error may be retrieved by error() method.

Return type:: bool

noDataValue(self) → float[source]¶

Returns no data value. If the block does not have a no data value the returned value is undefined.

Return type:: float
Returns:: No data value

See also

hasNoDataValue()

See also

setNoDataValue()

See also

resetNoDataValue()

static printValue(value: float, localized: bool = False) → str[source]¶

Print double value with all necessary significant digits. It is ensured that conversion back to double gives the same number.

Parameters:

value (float) – the value to be printed
localized (bool = False) – if True, use localized number format

Return type:

str

Returns:

string representing the value

reset(self, dataType: Qgis.DataType, width: int, height: int) → bool[source]¶

Reset block

Parameters:

dataType (Qgis.DataType) – raster data type
width (int) – width of data matrix
height (int) – height of data matrix

Return type:

bool

Returns:

True on success

resetNoDataValue(self)[source]¶: Reset no data value: if there was a no data value previously set, it will be discarded.

See also

noDataValue()

See also

hasNoDataValue()

See also

setNoDataValue()

setColor(self, row: int, column: int, color: int) → bool[source]¶

Set color on position

Parameters:

row (int) – row index
column (int) – column index
color (int) – the color to be set, QRgb value

Return type:

bool

Returns:

True on success

setColor(self, index: int, color: int) → bool[source]

Set color on index (indexed line by line)

Parameters:

index (int) – data matrix index (long type in Python)
color (int) – the color to be set, QRgb value

Return type:

bool

Returns:

True on success

setData(self, data: QByteArray | bytes | bytearray, offset: int = 0)[source]¶

Rewrite raw pixel data. If the data array is shorter than the internal array within the raster block object, pixels at the end will stay untouched. If the data array is longer than the internal array, only the initial data from the input array will be used. Optionally it is possible to set non-zero offset (in bytes) if the input data should overwrite data somewhere in the middle of the internal buffer.

Parameters:

data (Union[QByteArray, bytes, bytearray])
offset (int = 0)

setError(self, error: QgsError)[source]¶

Sets the last error

Parameters:: error (QgsError)

setImage(self, image: QImage | None) → bool[source]¶

Sets the block data via an image.

Return type:: bool
Returns:: True on success
Parameters:: image (Optional[QImage])

setIsData(self, row: int, column: int)[source]¶

Remove no data flag on pixel. If the raster block does not have an explicit no data value set then an internal map of no data pixels is maintained for the block. In this case it is possible to reset a pixel to flag it as having valid data using this method. This method has no effect for raster blocks with an explicit no data value set.

Parameters:

row (int) – row index
column (int) – column index

setIsData(self, index: int)[source]

Remove no data flag on pixel. If the raster block does not have an explicit no data value set then an internal map of no data pixels is maintained for the block. In this case it is possible to reset a pixel to flag it as having valid data using this method. This method has no effect for raster blocks with an explicit no data value set.

Parameters:: index (int) – data matrix index (long type in Python)

setIsNoData(self, row: int, column: int) → bool[source]¶

Set no data on pixel

Parameters:

row (int) – row index
column (int) – column index

Return type:

bool

Returns:

True on success

setIsNoData(self, index: int) → bool[source]

Set no data on pixel

Parameters:: index (int) – data matrix index (long type in Python)
Return type:: bool
Returns:: True on success

setIsNoData(self) → bool[source]

Set the whole block to no data

Return type:: bool
Returns:: True on success

setIsNoDataExcept(self, exceptRect: QRect) → bool[source]¶

Set the whole block to no data except specified rectangle

Return type:: bool
Returns:: True on success
Parameters:: exceptRect (QRect)

setNoDataValue(self, noDataValue: float)[source]¶

Sets cell value that will be considered as “no data”.

See also

noDataValue()

See also

hasNoDataValue()

See also

resetNoDataValue()

Parameters:: noDataValue (float)

setValid(self, valid: bool)[source]¶

Mark block as valid or invalid

Parameters:: valid (bool)

setValue(self, row: int, column: int, value: float) → bool[source]¶

Set value on position

Parameters:

row (int) – row index
column (int) – column index
value (float) – the value to be set

Return type:

bool

Returns:

True on success

setValue(self, index: int, value: float) → bool[source]

Set value on index (indexed line by line)

Parameters:

index (int) – data matrix index (long type in Python)
value (float) – the value to be set

Return type:

bool

Returns:

True on success

static subRect(extent: QgsRectangle, width: int, height: int, subExtent: QgsRectangle) → QRect[source]¶

For extent and width, height find rectangle covered by subextent. The output rect has x oriented from left to right and y from top to bottom (upper-left to lower-right orientation).

Parameters:

extent (QgsRectangle) – extent, usually the larger
width (int) – numbers of columns in theExtent
height (int) – numbers of rows in theExtent
subExtent (QgsRectangle) – extent, usually smaller than theExtent

Return type:

QRect

Returns:

the rectangle covered by sub extent

toString(self) → str[source]¶

Return type:: str

static typeIsColor(type: Qgis.DataType) → bool[source]¶

Returns True if data type is color

Parameters:: type (Qgis.DataType)
Return type:: bool

static typeIsNumeric(type: Qgis.DataType) → bool[source]¶

Returns True if data type is numeric

Parameters:: type (Qgis.DataType)
Return type:: bool

static typeSize(dataType: Qgis.DataType) → int[source]¶

Returns the size in bytes for the specified dataType.

Parameters:: dataType (Qgis.DataType)
Return type:: int

static typeWithNoDataValue(dataType: Qgis.DataType)[source]¶

For given data type returns wider type and sets no data value

Parameters:: dataType (Qgis.DataType) -> (Qgis.DataType)

value(self, row: int, column: int) → float[source]¶

Read a single value if type of block is numeric. If type is color, returned value is undefined.

Parameters:

row (int) – row index
column (int) – column index

Return type:

float

Returns:

value

See also

valueAndNoData()

value(self, index: int) → float[source]

Reads a single value if type of block is numeric. If type is color, returned value is undefined.

Parameters:: index (int) – data matrix index (long type in Python)
Return type:: float
Returns:: value

See also

valueAndNoData()

static valueBytes(dataType: Qgis.DataType, value: float) → QByteArray[source]¶

Gets byte array representing a value.

Parameters:

dataType (Qgis.DataType) – data type
value (float) – value

Return type:

QByteArray

Returns:

byte array representing the value

width(self) → int[source]¶

Returns the width (number of columns) of the raster block.

See also

height()

Return type:: int