This is how I get the PCs at the specified scale and in the specified region:

# Get the Principal Components (PCs) 

pcImage = getPrincipalComponents(centered, scale, region) #this return PCA image 
# Plot each PC as a new layer
for i in range(bandNames.length().getInfo()):
    band = pcImage.bandNames().get(i)

Here is the pca functionin which am passing an ee image:

 # Principal Components (PC) in the region as a new image.
def getPrincipalComponents(centered, scale, region):
    #Collapse the bands of the image into a 1D array per pixel
    arrays = centered.toArray()
    #Compute the covariance of the bands within the region.

    #Get the 'array' covariance result and cast to an array.
    # This represents the band-to-band covariance within the region.
    covarArray = ee.Array(covar.get('array'))
    #Perform an eigen analysis and slice apart the values and vectors.
    eigens = covarArray.eigen()
    # This is a P-length vector of Eigenvalues.
    eigenValues = eigens.slice(1, 0, 1)
    # This is a PxP matrix with eigenvectors in rows.
    eigenVectors = eigens.slice(1, 1)
    # Convert the array image to 2D arrays for matrix computations.
    arrayImage = arrays.toArray(1)
    #Left multiply the image array by the matrix of eigenvectors.
    principalComponents = ee.Image(eigenVectors).matrixMultiply(arrayImage)
    # Turn the square roots of the Eigenvalues into a P-band image.
    sdImage = ee.Image(eigenValues.sqrt())\
    # Turn the PCs into a P-band image, normalized by SD.
    # Throw out an an unneeded dimension, [[]] -> [].
    # Make the one band array image a multi-band image, [] -> image.
    # Normalize the PCs by their SDs.
    return principalComponents\
  • 2
    Welcome on GIS.SE. Could you please add a bit more of context to your question? That would be great. In addition, I have an error getPrincipalComponents not definde when I try to run it. Try to share a MWE. – s.k Apr 18 '20 at 6:28
  • what is the line which throws the error? – Kadir Şahbaz Apr 18 '20 at 12:53
  • actually the error in pcimage it says that it ihas long value and expected is string – Fakhar Elahi Apr 19 '20 at 7:34
  • Check the values of centered, region and scale. One of them probably is long, but expected a string. Check using print(type(centered), type(scale), type(region)) – Kadir Şahbaz Apr 19 '20 at 10:42
  • here are the values of these three <class 'ee.image.Image'> <class 'int'> <class 'ee.geometry.Geometry'> ( function retrurns pcImage but it can't be visulize using folium) – Fakhar Elahi Apr 20 '20 at 4:18

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