PyQGIS Creating Numpy Array from QByteArray (QgsRasterBlock.data()) and vice versa (QGIS3) ...
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PyQGIS Creating Numpy Array from QByteArray (QgsRasterBlock.data()) and vice versa (QGIS3)
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I read that handling the pixel values in the QgsRasterBlock object as QByteArrays and creating numpy arrays directly from the QByteArrays is possible and efficient (as compared to the method described below).
So my first question: Is this true?
My second question: What does the numpy function to create an array from QByteArray look like? And which function can I use to go back again?
Context:
I am looking for a way to convert the values contained in a QgsRasterLayer object to a numpy array and vice versa without using any GDAL methods.
To obtain the numpy array I go through QgsRasterDataProvider to QgsRasterBlock and then read the values into a numpy array through the QgsRasterBlock.value(i,j) method. This is not very elegant, but runs in an acceptable time.
Analogously - after working with the numpy array - I change the values in the QgsRasterBlock through the QgsRasterBlock.setValue(i, j, value) method, which takes forever and is not acceptable for my application... so I am looking for an alternative!
pyqgis numpy pyqgis-3
asked 2 mins ago
jo11hejo11he
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I read that handling the pixel values in the QgsRasterBlock object as QByteArrays and creating numpy arrays directly from the QByteArrays is possible and efficient (as compared to the method described below).
So my first question: Is this true?
My second question: What does the numpy function to create an array from QByteArray look like? And which function can I use to go back again?
Context:
I am looking for a way to convert the values contained in a QgsRasterLayer object to a numpy array and vice versa without using any GDAL methods.
To obtain the numpy array I go through QgsRasterDataProvider to QgsRasterBlock and then read the values into a numpy array through the QgsRasterBlock.value(i,j) method. This is not very elegant, but runs in an acceptable time.
Analogously - after working with the numpy array - I change the values in the QgsRasterBlock through the QgsRasterBlock.setValue(i, j, value) method, which takes forever and is not acceptable for my application... so I am looking for an alternative!
pyqgis numpy pyqgis-3
asked 2 mins ago
jo11hejo11he
11
New contributor
jo11he is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
I read that handling the pixel values in the QgsRasterBlock object as QByteArrays and creating numpy arrays directly from the QByteArrays is possible and efficient (as compared to the method described below).
So my first question: Is this true?
My second question: What does the numpy function to create an array from QByteArray look like? And which function can I use to go back again?
Context:
I am looking for a way to convert the values contained in a QgsRasterLayer object to a numpy array and vice versa without using any GDAL methods.
To obtain the numpy array I go through QgsRasterDataProvider to QgsRasterBlock and then read the values into a numpy array through the QgsRasterBlock.value(i,j) method. This is not very elegant, but runs in an acceptable time.
Analogously - after working with the numpy array - I change the values in the QgsRasterBlock through the QgsRasterBlock.setValue(i, j, value) method, which takes forever and is not acceptable for my application... so I am looking for an alternative!
pyqgis numpy pyqgis-3
asked 2 mins ago
jo11hejo11he
11
New contributor
jo11he is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
I read that handling the pixel values in the QgsRasterBlock object as QByteArrays and creating numpy arrays directly from the QByteArrays is possible and efficient (as compared to the method described below).
So my first question: Is this true?
My second question: What does the numpy function to create an array from QByteArray look like? And which function can I use to go back again?
Context:
I am looking for a way to convert the values contained in a QgsRasterLayer object to a numpy array and vice versa without using any GDAL methods.
To obtain the numpy array I go through QgsRasterDataProvider to QgsRasterBlock and then read the values into a numpy array through the QgsRasterBlock.value(i,j) method. This is not very elegant, but runs in an acceptable time.
Analogously - after working with the numpy array - I change the values in the QgsRasterBlock through the QgsRasterBlock.setValue(i, j, value) method, which takes forever and is not acceptable for my application... so I am looking for an alternative!
pyqgis numpy pyqgis-3
pyqgis numpy pyqgis-3
asked 2 mins ago
jo11hejo11he
11
New contributor
jo11he is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 mins ago
jo11hejo11he
11
New contributor
jo11he is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 mins ago
jo11hejo11he
11
New contributor
jo11he is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked 2 mins ago
jo11hejo11he
11
asked 2 mins ago
jo11hejo11he
11
11
New contributor
jo11he is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
jo11he is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
jo11he is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
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