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How to read each row of a column with pythonCaller?

M

I am trying to access each row of the excel data I read with pythoncaller. How can I do that

 

        coulumnData = feature.getAttribute('Column1')
        data = str(coulumnData).split()
        for row in data:
            print(row)

and how do I read FLOAT values as well?

 

I do not understand what kind of object is returned by feature.getAttribute. If I print coulumnData, it is printed nicely row by row. But, how do I access those row of data? I want to do something like

 

        coulumnData = feature.getAttribute('Column1')
        data = str(coulumnData).split()
        print(data[10])

 

Best answer by david_r

moostang88 wrote:

When I try to do this:

        coulumnData = feature.getAttribute('Column1')  
        for row in coulumnData:
            print(row)

I get this error:

image.png

The PythonCaller is called once for each row in your Excel, meaning you cannot access all rows by the column name. You'll have to add them up yourself, e.g.

import fme
import fmeobjects
 
 
class FeatureProcessor(object):
 
    def __init__(self):
        """Base constructor for class members."""
        self.column1_values = list()
 
    def input(self, feature):
        """This method is called for each FME Feature entering the 
        PythonCaller. If knowledge of all input Features is not required for 
        processing, then the processed Feature can be emitted from this method 
        through self.pyoutput(). Otherwise, the input FME Feature should be 
        cached to a list class member and processed in process_group() when 
        'Group by' attributes(s) are specified, or the close() method.
 
        :param fmeobjects.FMEFeature feature: FME Feature entering the 
            transformer.
        """
        value = feature.getAttribute('column1')
        if value is not None:
            self.column1_values.append(value)
        self.pyoutput(feature)
 
    def close(self):
        """This method is called once all the FME Features have been processed
        from input().
        """
        # Do some aggregate processing here...
        print(self.column1_values)

 

 

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6 replies

david_r
Celebrity
  • david_rCelebrity
  • August 17, 2023

You may want to take a look at the documentation for feature.getAttribute():

https://docs.safe.com/fme/html/fmepython/api/fmeobjects/_feature/fmeobjects.FMEFeature.getAttribute.html#fmeobjects.FMEFeature.getAttribute

To iterate over all the attributes in a Python block, do something like:

for attr_name in feature.getAllAttributeNames():
    attr_value = feature.getAttribute(attr_name)
    print('{} has value {}'.format(attr_name, attr_value))

 

M
  • moostang88
  • Author
  • August 17, 2023

I did that as well (from another post). But, when I 

print('{} has value {}'.format(attr_name, attr_value))

I get this. 

 

image.png 

Now, I want to access each row as some sort of list. But, attr_value is some kind of FME object. How do I convert it to a list so that I can access each element one by one. I want to do something like

attr_value[0] = 'Apple'
attr_value[1] = 'Orange'
attr_value[2] = 'Banana'

But, right I only have this:

print(attr_value)
 
Apple
Orange
Banana

I want to access each element of attr_value. How do I do that? 

 

 

M
  • moostang88
  • Author
  • August 17, 2023

When I try to do this:

        coulumnData = feature.getAttribute('Column1')  
        for row in coulumnData:
            print(row)

I get this error:

image.png

david_r
Celebrity
  • david_rCelebrity
  • Best Answer
  • August 17, 2023
moostang88 wrote:

When I try to do this:

        coulumnData = feature.getAttribute('Column1')  
        for row in coulumnData:
            print(row)

I get this error:

image.png

The PythonCaller is called once for each row in your Excel, meaning you cannot access all rows by the column name. You'll have to add them up yourself, e.g.

import fme
import fmeobjects
 
 
class FeatureProcessor(object):
 
    def __init__(self):
        """Base constructor for class members."""
        self.column1_values = list()
 
    def input(self, feature):
        """This method is called for each FME Feature entering the 
        PythonCaller. If knowledge of all input Features is not required for 
        processing, then the processed Feature can be emitted from this method 
        through self.pyoutput(). Otherwise, the input FME Feature should be 
        cached to a list class member and processed in process_group() when 
        'Group by' attributes(s) are specified, or the close() method.
 
        :param fmeobjects.FMEFeature feature: FME Feature entering the 
            transformer.
        """
        value = feature.getAttribute('column1')
        if value is not None:
            self.column1_values.append(value)
        self.pyoutput(feature)
 
    def close(self):
        """This method is called once all the FME Features have been processed
        from input().
        """
        # Do some aggregate processing here...
        print(self.column1_values)

 

 

M
  • moostang88
  • Author
  • August 17, 2023

"PythonCaller is called once for each row in your Excel".. now that statement answers all my confusion !! Thanks !

 

Final question @david_r. How do I expose the values outside of python?

 

 

david_r
Celebrity
  • david_rCelebrity
  • August 17, 2023
moostang88 wrote:

"PythonCaller is called once for each row in your Excel".. now that statement answers all my confusion !! Thanks !

 

Final question @david_r. How do I expose the values outside of python?

 

 

You can either expose them in the lower part of the PythonCaller dialog, or using an AttributeExposer.

image

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