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After playing around with the Model Builder and looking at the python scripts of what I make, I noticed some syntax which I can't find the definition anywhere. Here is a snippet of the python script from a model:

outputs_13=processing.runalg("qgis:fieldcalculator", outputs_12['SAVENAME'], ID, 1, 10, 0, True, $rownum , None)
outputs_14=processing.runalg("qgis:deletecolumn", outputs_13['OUTPUT_LAYER'], longitude, None)
outputs_15=processing.runalg("qgis:deletecolumn", outputs_14['SAVENAME'], latitude, savename_alg15)
outputs_16=processing.runalg("qgis:clip", outputs_15['SAVENAME'], vectorlayer_layer1, None)
outputs_17=processing.runalg("qgis:fieldcalculator", outputs_16['OUTPUT'], Score, 0, 10, 0, True, 2, output_layer_alg17)

Can someone please explain the purpose of ['SAVENAME'], ['OUTPUT'] and ['OUTPUT_LAYER']?

I am trying to develop a script but keep getting errors linked to these terms and I am unsure as to how they are used.

share|improve this question

Look at Using processing algorithms from the console

import processing 
 ALGORITHM: Field calculator
  INPUT_LAYER <ParameterVector>
  FIELD_NAME <ParameterString>
  FIELD_TYPE <ParameterSelection>
  FIELD_LENGTH <ParameterNumber>
  FIELD_PRECISION <ParameterNumber>
  NEW_FIELD <ParameterBoolean>
  FORMULA <ParameterString>
  OUTPUT_LAYER <OutputVector>

      FIELD_TYPE(Field type)
     0 - Float
     1 - Integer
     2 - String
     3 - Date
ALGORITHM: Delete column
LAYERNAME <ParameterVector>
COLUMN <ParameterTableField from LAYERNAME>
SAVENAME <OutputVector>
share|improve this answer
Thanks gene, it's made a bit more sense. Just for clarification: ['SAVENAME'] is used if you want to temporarily save a layer (eg. saving the layer as 'None'); ['OUTPUT'] is used if you want to call a layer later; and ['OUTPUT_LAYER'] is used when you want the final result to be loaded in the interface? – Joseph Jun 2 '14 at 9:05

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