Comparing between layers name and merging layers having same name using PyQGIS?

Question

I'm trying to write python script in QGIS to merge layers having the same name.

To do that I specify the name of layer in the script, so all layers having this name, will be merged. However, since I have a lot of names this is not practical. I tried to convert the names type from unicode to list to be able to iterate in the list of names.

In this script, I specify layer name. I want to iterate over all names and compare them to finally merge layers having same name.

import qgis.core
import processing
def __init__(self, iface):
    self.iface = iface
lyr_list=[]
count=1
layers=iface.mapCanvas().layers()
for i in layers:
    if i.name() == 'layer_name':
        lyr_list.append(i)

processing.runandload("qgis:mergevectorlayers", lyr_list, "memory:merged")

Answer 1

Following code has an example of parameters dictionary and, I modified some little thing in your code because you are tagged this question with qgis-3 and 'runandload' doesn't exist as processing method in pyqgis3. I also modified 'layer_name' for working with my own layers.

import qgis.core
import processing
def __init__(self, iface):
    self.iface = iface
lyr_list=[]
count=1
layers=iface.mapCanvas().layers()
for i in layers:
    if i.name() == 'polygon1':
        lyr_list.append(i)

processing.runAndLoadResults("qgis:mergevectorlayers", 
                             {'LAYERS': lyr_list, 
                              'OUTPUT': "memory:merged"})

So, I loaded same layer twice in Map Canvas of QGIS 3 and, I ran above script in Python Console.

Result (layer Merged) can be observed in following image with attributes table. It worked.