[Tutor] removing xml elements with ElementTree
An opportunity to work in Python, and the necessity of working with some XML
too large to visualize, got me thinking about an answer Alan Gauld had written
to me a few years ago
(https://mail.python.org/pipermail/tutor/2015-June/105810.html). I have
applied that information in this script, but I have another question :)
Let's say I have an xml file like this:
-- order.xml
Bob
321 Main St
D20
4
CS211
1
BL5
7
AC400
1
-- end order.xml
Items CS211 and AC400 are not valid items, and I want to remove their
nodes. I came up with the following (python 3.6.7 on linux):
xml_delete_test.py
import os
import xml.etree.ElementTree as ET
hd = os.path.expanduser('~')
inputxml = os.path.join(hd,'order.xml')
outputxml = os.path.join(hd,'fixed_order.xml')
valid_items = ['D20','BL5']
tree = ET.parse(inputxml)
root = tree.getroot()
saleslines = root.find('saleslines').findall('salesline')
for e in saleslines[:]:
if e.find('item').text not in valid_items:
saleslines.remove(e)
tree.write(outputxml)
-- end xml_delete_test.py --
The above code runs without error, but simply writes the original file to disk.
The desired output would be:
-- fixed_order.xml
Bob
321 Main St
D20
4
BL5
7
-- end fixed_order.xml
What I find particularly confusing about the problem is that after running
xml_delete_test.py in the Idle editor, if I go over to the shell and type
saleslines, I can see that it's now a list of two elements. I run the
following:
for i in saleslines:
print(i.find('item').text)
and I see that it's D20 and BL5, my two valid items. Yet when I write tree out
to the disk, it has the original four. Do I need to refresh tree somehow?
Thanks!
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Re: [Tutor] removing xml elements with ElementTree
street.swee...@mailworks.org wrote:
> An opportunity to work in Python, and the necessity of working with some
> XML too large to visualize, got me thinking about an answer Alan Gauld had
> written to me a few years ago
> (https://mail.python.org/pipermail/tutor/2015-June/105810.html). I have
> applied that information in this script, but I have another question :)
>
> Let's say I have an xml file like this:
>
> -- order.xml
>
>
> Bob
> 321 Main St
>
>
> D20
> 4
>
>
> CS211
> 1
>
>
> BL5
> 7
>
>
> AC400
> 1
>
>
>
>
> -- end order.xml
>
> Items CS211 and AC400 are not valid items, and I want to remove their
> nodes. I came up with the following (python 3.6.7 on linux):
>
> xml_delete_test.py
>
> import os
> import xml.etree.ElementTree as ET
>
> hd = os.path.expanduser('~')
> inputxml = os.path.join(hd,'order.xml')
> outputxml = os.path.join(hd,'fixed_order.xml')
>
> valid_items = ['D20','BL5']
>
> tree = ET.parse(inputxml)
> root = tree.getroot()
> saleslines = root.find('saleslines').findall('salesline')
> for e in saleslines[:]:
> if e.find('item').text not in valid_items:
> saleslines.remove(e)
>
> tree.write(outputxml)
>
> -- end xml_delete_test.py --
>
> The above code runs without error, but simply writes the original file to
> disk. The desired output would be:
>
> -- fixed_order.xml
>
>
> Bob
> 321 Main St
>
>
> D20
> 4
>
>
> BL5
> 7
>
>
>
>
> -- end fixed_order.xml
>
> What I find particularly confusing about the problem is that after running
> xml_delete_test.py in the Idle editor, if I go over to the shell and type
> saleslines, I can see that it's now a list of two elements. I run the
> following:
>
> for i in saleslines:
> print(i.find('item').text)
>
> and I see that it's D20 and BL5, my two valid items. Yet when I write
> tree out to the disk, it has the original four. Do I need to refresh tree
> somehow?
>
> Thanks!
First of all, thank you for this clear and complete problem description!
> saleslines = root.find('saleslines').findall('salesline')
Here findall()
returns a new list of matches which is completely independent of the element
tree. Therefore
> saleslines.remove(e)
will remove the element e from this indepent list, and only from that.
To remove an element from the tree you have to know its parent, and then
parent_element.remove(child_element)
will actually modify the tree.
In your case the parent is always , so you can restrict yourself
to its children:
saleslines = root.find('saleslines')
for e in saleslines.findall('salesline'):
if e.find('item').text not in valid_items:
saleslines.remove(e)
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[Tutor] Help
How do I make Python 3 pick a random variable out of a set of variables I give it? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Help
On 20/03/19 14:30, Eric Oh Yeah Yeah wrote: How do I make Python 3 pick a random variable out of a set of variables I give it? There are several options but if you look in the random module you should find one that suits your particular needs. choice() or randrange() may be good options. If that's not enough of a hint come back with more specific details about what kind of "set of variables" you are using. Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] is there a graphics library for common tkinter Button functions?
Hi, Is there a "graphics library" of common button uses? that is things like forward record, back record, 1st record, last record, printer, save and the likes. I don't have very artistic abilities, so would prefer to save making my own library. Thank you Chris Roy-Smith ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] is there a graphics library for common tkinter Button functions?
On 20/03/19 22:43, Chris Roy-Smith wrote: Is there a "graphics library" of common button uses? that is things like forward record, back record, 1st record, last record, printer, save and the likes. The short answer is no. But you can assign any bitmap image to a button. (You can use other formats too but bitmaps are easiest in my experience!) But putting an image on the button does not give it any functionality. You need to program that yourself. HTH, Alan G. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
