Question

I have a XML document “data.xml”:
I need to write python script which can replace all the value nodes with tag ‘Num’ with the new numbers and write it back to the disk.
the difference is that the new value is not string, but a series of continous increasing number, like 1000,1100,1200,1300…
I hav done research online, most code samples are string replace, not such variable replace. Anybody hav good idea? sample as follow:

before change:

<Param><Num>123</Num></Param>
<Param><Num>123</Num></Param>
<Param><Num>123</Num></Param>


after change:

<Param><Num>1000</Num></Param>
<Param><Num>1100</Num></Param>
<Param><Num>1200</Num></Param>


Answer 1

Quite easy to achieve with the lxml library

from lxml import  objectify

class Parser(object):
    def __init__(self, tree, counter_start, counter_interval):
        self.tree = tree
        self.root = tree.getroot()
        self.counter_start = counter_start
        self.counter_interval = counter_interval

    def parse(self):
        counter = self.counter_start
        # for loop to iter voltage items
        # using counter += counter_interval to set the value for example
        # save the tree within the parser class or in the handle function


def handle(file):
    f = open(file)
    tree = objectify.parse(f)
    parser = Parser(tree, 1000, 100)
    parser.parse()
    f.close()

handle("/Desktop/bar.XML")