Defining and Calling Functions in Python

Question

I am diving into defining and calling functions, but I'm not sure if I have grasped the concept. I have an if/else statement in a python that loops through a folder containing XML documents. In my script below, I have a block of code that I have to re-type after each if xmlfilename == condition.

I'm thinking that if I define the block starting at if element.tag == as a function, I can just call it after each conditional if xmlfilename == I think I've figured out how to define the function, but I'm not sure how I would call it after the if xmlfilename == condition arises. Can anyone suggest how to do this or am I way off on how defining and using functions works?

if xmlfilename == "Soil":

  if element.tag == "timeinfo":
    tree = root.find(".//timeinfo")
    tree.clear()

    if SINGLEDATE == "'Single Date'":

        child1 = ET.SubElement(tree, "sngdate")
        child2 = ET.SubElement(child1, "caldate")
        child3 = ET.SubElement(child1, "time")


    if MULTIPLEDATES == "'Multiple Dates'":                        

        parent = ET.SubElement(tree, "mdattim")

        for x, y in enumerate(Date2.split(";")):                         
            #print x, y
            replaceMD = y.replace('/', '-')

            if x == 0:
                #print x, y
                child1 = ET.SubElement(parent, "sngdate")
                child2 = ET.SubElement(child1, "caldate")
                child3 = ET.SubElement(child1, "time")              
                child2.text = replaceMD
                child3.text = "unknown"
            else:
                child1 = ET.SubElement(parent, "sngdate")
                child4 = ET.SubElement(child1, "caldate")
                child4.text = replaceMD

if xmlfilename == "Tree":
   # Do the same thing as above starting at "if element.tag == "timeinfo":"

Answer 1

If the functionality is exactly the same for "Soil" and "Tree" you can just modify the if statement to the following:

if xmlfilename == "Soil" or xmlfilename == "Tree":
    # The rest of your code

Although you may choose to put your code block in a function to organize your code a bit better:

def read_xml_data():
    # Your code block

if xmlfilename == "Soil" or xmlfilename == "Tree":
    read_xml_data()

Functions are even more useful when some variables in your code block need to change from one invocation to another based on some parameter. For example:

def read_xml_data(param):
   if param == "value1":
      # do one thing
   elif param == "value2":
      # do something else