OK here's the answer.
I have discovered the processing toolbox from which there was a simple solution: As per http://qgis.org/de/docs/user_manual/processing/console.html
From the console you can get a list of all the algorithms available which contain the word "merge" by typing:
import processing
processing.alglist("merge")
Then you could find out how to use the most appropriate function with:
processing.alghelp("qgis:mergevectorlayers")
Then simply use the algorithm in your script as follows:
processing.runalg("qgis:mergevectorlayers", layer1, layer2,"outputfilename.shp")
On the other hand manually merging shapes may still be useful. For those who still want to manually copy features from an input layer into some destination layer with attributes you need to first make sure the destination layer has those fields.
old_attribute_List = input_layer.dataProvider().fields().toList()
new_attribute_List=[]
for attrib in old_attribute_List:
if destination_layer.fieldNameIndex(attrib.name())==-1:
new_attribute_List.append(QgsField(attrib.name(),attrib.type()))
destination_layer_data_provider.addAttributes(new_attribute_List)
destination_layer.updateFields()
Then to manually copy over the features you can do:
destination_layer.startEditing()
cfeature = QgsFeature()
cfeatures=[]
xfeatures = input_layer.getFeatures()
for xfeature in xfeatures:
xgeometry = xfeature.geometry()
#GEOMETRY TRANSFORM GOES HERE IF DESTINATION CRS DIFFERS FROM INPUT CRS
cfeature_Attributes=[]
cfeature_Attributes.extend(xfeature.attributes())
cfeature.setGeometry(xgeometry)
cfeature.setAttributes(cfeature_Attributes)
cfeatures.append(cfeature)
destination_layer_data_provider.addFeatures(cfeatures)
destination_layer_data_provider.commitChanges()
Best Answer
If the XYZ files are just delineated text files, you could just copy/paste in notepad or some such editor. Six files doesn't seem like many. Sometimes you don't need to automate...
However, I think there are a few options that won't require ArcPy.
Things that come to mind:
Load the data into a new feature class or table.
Try the append tool.
Try the merge tool.
Try the union tool.