[issue41892] use both "for in" and "ElementTree.remove" has a index bug
WoodyWoo added the comment: Could I say the mutable sequence containing not the object but the pointer like C++. So they can changed in def functions. -- ___ Python tracker <https://bugs.python.org/issue41892> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41899] Poor example for Element.remove()
WoodyWoo added the comment: Could I say the mutable sequence containing not the object but the pointer like C++. So they can changed in def functions. -- ___ Python tracker <https://bugs.python.org/issue41899> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41892] use both "for in" and "ElementTree.remove" has a index bug
WoodyWoo added the comment:
@eric.smith @scoder @serhiy.storchaka Thank U all.
I get what to do,and still think the "for in" structure should rebuilding.
All three methods:
import xml.etree.ElementTree as ET
xmlstr=\
r'''
2
2008
141100
5
2011
59900
69
2011
13600
69
2011
13600
'''
print(xmlstr)
#orginal code
root = ET.fromstring(xmlstr)
for country in root.findall('country'):
rank = int(country.find('rank').text)
if rank > 50:
root.remove(country)
print("___orginal___")
for country in root.findall('country'):
print (country.get("name"))
print("^^^orginal\n")
#wrong code in my mind
root = ET.fromstring(xmlstr)
for country in root:
rank = int(country.find('rank').text)
if rank > 50:
root.remove(country)
print("___bad___")
for country in root.findall('country'):
print (country.get("name"))
print("^^^bad\n")
#my code
root = ET.fromstring(xmlstr)
index=0
count=len(root.findall("./*"))
while index 50:
root.remove(root[index])
index=index+0
count=count-1 # avoid index err
continue
index=index+1
print("___new___")
for country in root.findall('country'):
print (country.get("name"))
print("^^^new\n")
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[issue41899] Poor example for Element.remove()
WoodyWoo added the comment: The docs should specially tell that when need root.remove(child) must works with "for child in root.findall()". And my code with "while if continue" could make root.insert(index,newchild) easily. -- ___ Python tracker <https://bugs.python.org/issue41899> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41899] Poor example for Element.remove()
WoodyWoo added the comment:
My fault.
"for country in root.findall('country')“ is not working as same as "for country
in root"
all 3 method below:
import xml.etree.ElementTree as ET
xmlstr=\
r'''
2
2008
141100
5
2011
59900
69
2011
13600
69
2011
13600
'''
print(xmlstr)
#orginal code
root = ET.fromstring(xmlstr)
for country in root.findall('country'):
rank = int(country.find('rank').text)
if rank > 50:
root.remove(country)
print("___orginal___")
for country in root.findall('country'):
print (country.get("name"))
print("^^^orginal\n")
#wrong code in my mind
root = ET.fromstring(xmlstr)
for country in root:
rank = int(country.find('rank').text)
if rank > 50:
root.remove(country)
print("___bad___")
for country in root.findall('country'):
print (country.get("name"))
print("^^^bad\n")
#my code
root = ET.fromstring(xmlstr)
index=0
count=len(root.findall("./*"))
while index 50:
root.remove(root[index])
index=index+0
count=count-1 # avoid index err
continue
index=index+1
print("___new___")
for country in root.findall('country'):
print (country.get("name"))
print("^^^new\n")
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[issue41899] Poor example for Element.remove()
WoodyWoo added the comment:
#new code to avoid an err
index=0
count=len(root.findall("./*"))
while index 50:
root.remove(root[index])
index=index+0
count=count-1 # avoid index err
continue
index=index+1
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[issue41899] Poor example for Element.remove()
New submission from WoodyWoo :
We can remove elements using Element.remove(). Let’s say we want to remove all
countries with a rank higher than 50:
>>>
>>> for country in root.findall('country'):
... rank = int(country.find('rank').text)
... if rank > 50:
... root.remove(country)
...
>>> tree.write('output.xml')
When the original xml has over 2 country with rank>50,and they are one by one
neighborly siblings element,the upper code will delete the 1st 3rd 5th and more
odd No. country.
A proper example should be:
index=0
while index < len(root.findall("./*")):
rank = int (root[index].find("rank").text)
if rank>50:
root.remove(root[index])
index=index+0
continue
index=index+1
I think "for each in list" should not work by index,but should work by pointer
like thing,could be a list of pointers.
A finial solution should be like this --- when the "for each in list" was
acting,the pointers list would be fixed,and you need not to worry about the
"list" changing.
--
assignee: docs@python
components: Documentation
messages: 377726
nosy: WoodyWoo, docs@python
priority: normal
severity: normal
status: open
title: Poor example for Element.remove()
type: behavior
versions: Python 3.8
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[issue41892] use both "for in" and "ElementTree.remove" has a index bug
WoodyWoo added the comment: I think "for each in list" should not work by index,but should work by pointer like thing,could be a list of pointers. When the "for each in list" was acting,the pointers list would be fixed,and you need not to worry about the "list" changing. -- ___ Python tracker <https://bugs.python.org/issue41892> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41892] use both "for in" and "ElementTree.remove" has a index bug
WoodyWoo added the comment: Only that makes "for each in list" literally. -- ___ Python tracker <https://bugs.python.org/issue41892> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41892] use both "for in" and "ElementTree.remove" has a index bug
WoodyWoo added the comment: I'm green hand in Coding. But I think the problem caused by "for each in list". Anything changed in "list" should not act at once,but should act when "for end" or break. -- ___ Python tracker <https://bugs.python.org/issue41892> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41892] use both "for in" and "ElementTree.remove" has a index bug
Change by WoodyWoo : -- title: use both "for" and "ElementTree.remove" has a index bug -> use both "for in" and "ElementTree.remove" has a index bug ___ Python tracker <https://bugs.python.org/issue41892> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue41892] use both "for" and "ElementTree.remove" has a index bug
New submission from WoodyWoo :
#Just run it in Python v3.8.6 of win7 32bit
import xml.etree.ElementTree as ET
xmlstr='''
'''
etroot = ET.fromstring(xmlstr)
for ELEMchild in etroot:
if ELEMchild.get("no") == "1" :
etroot.remove(ELEMchild) #so far so good
print (ELEMchild.tag)
#It should be : "b /n c" or "a /n b /n c",I can live with it both.
#But it is : "a /n c".
#The index of ELEMchild should not +1 when there was a remove method worked
on one of the before ELEMs.
#I was forced to use while and if to control the index +1/+0.
#BTW,ELEM has no method returning index in siblings, which is buging me too.
--
components: XML
messages: 377698
nosy: WoodyWoo
priority: normal
severity: normal
status: open
title: use both "for" and "ElementTree.remove" has a index bug
type: behavior
versions: Python 3.8
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