Fit PCA

Principal component analysis (PCA). Linear dimensionality reduction using Singular Value Decomposition of the data to project it to a lower dimensional space. The input data is centered but not scaled for each feature before applying the SVD.

Usage:

1. Start the algorithm from the Processing Toolbox panel.

2. Select a raster layer to process and click run.

   

Parameters

Transformer [string]

Scikit-learn python code. See PCA for information on different parameters. Default:

from sklearn.pipeline import make_pipeline
from sklearn.preprocessing import StandardScaler
from sklearn.decomposition import PCA

pca = PCA\(n_components=0.95\)
transformer = make_pipeline\(StandardScaler\(\), pca\)

Raster layer with features [raster]

Raster layer with feature data X used for fitting the transformer. Mutually exclusive with parameter: Training dataset

Sample size [number]

Approximate number of samples drawn from raster. If 0, whole raster will be used. Note that this is only a hint for limiting the number of rows and columns. Default: 1000

Training dataset [file]

Training dataset pickle file used for fitting the transformer. Mutually exclusive with parameter: Raster layer with features

Outputs

Output transformer [fileDestination]

Pickle file destination.

Command-line usage

>qgis_process help enmapbox:fitpca:

----------------
Arguments
----------------

transformer: Transformer
    Default value:    from sklearn.pipeline import make_pipeline
from sklearn.preprocessing import StandardScaler
from sklearn.decomposition import PCA

pca = PCA(n_components=0.95)
transformer = make_pipeline(StandardScaler(), pca)
    Argument type:    string
    Acceptable values:
        - String value
        - field:FIELD_NAME to use a data defined value taken from the FIELD_NAME field
        - expression:SOME EXPRESSION to use a data defined value calculated using a custom QGIS expression
featureRaster: Raster layer with features (optional)
    Argument type:    raster
    Acceptable values:
        - Path to a raster layer
sampleSize: Sample size (optional)
    Default value:    1000
    Argument type:    number
    Acceptable values:
        - A numeric value
        - field:FIELD_NAME to use a data defined value taken from the FIELD_NAME field
        - expression:SOME EXPRESSION to use a data defined value calculated using a custom QGIS expression
dataset: Training dataset (optional)
    Argument type:    file
    Acceptable values:
        - Path to a file
outputTransformer: Output transformer
    Argument type:    fileDestination
    Acceptable values:
        - Path for new file

----------------
Outputs
----------------

outputTransformer: <outputFile>
    Output transformer