473,700 Members | 2,564 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

Removing from a List in Place

I'm going to assume that it's supposed to work like this, but could
someone tell me the reasoning behind it? I.E. why is 3 skipped?
>>alist=[1,2,3]
for item in alist:
.... print item
.... if item==2:
.... alist.remove(it em)
....
1
2
>>>
Bonus Question:
Can we make this behave more intuitiviely in Python 3000?

-Greg
--
Gregory Piñero
Chief Innovation Officer
Blended Technologies
(www.blendedtechnologies.com)
Sep 5 '06 #1
3 1166
I'm going to assume that it's supposed to work like this, but could
someone tell me the reasoning behind it? I.E. why is 3 skipped?
Because:
>>alist[2]
3

You are removing the third item, not the second.

Sep 5 '06 #2
bayerj wrote:
I'm going to assume that it's supposed to work like this, but could
someone tell me the reasoning behind it? I.E. why is 3 skipped?

Because:
>alist[2]
3

You are removing the third item, not the second.
This is incorrect.
You may need to remind yourself that the arg of remove is a value to be
searched for and then removed, not an index. del alist[2] would remove
the third item.

You may have been confused by the OP's obfuscatory example alist = [1,
2, 3].
Consider this equivalent:
| >>alist = ['foo', 'bar', 'zot']
| >>for item in alist:
| ... print item
| ... if item == 'bar':
| ... alist.remove(it em)
| ...
| foo
| bar
| >>alist
| ['foo', 'zot']
| >>>

HTH,
John

Sep 5 '06 #3
On 5 Sep 2006 16:05:36 -0700, bayerj <ba****@in.tum. dewrote:
I'm going to assume that it's supposed to work like this, but could
someone tell me the reasoning behind it? I.E. why is 3 skipped?

Because:
>alist[2]
3

You are removing the third item, not the second.
Actually, he's removing 2 from the list, but then the length of the
list shrinks by 1 and iteration stops.

The example would have been better if alist = ['a','b','c'] and 'b' was removed.

L.remove(value) -- remove first occurrence of value

you were possibly thinking of alist.pop(2), which removes the item
alist[2] from alist

HTH :)
--

Tim Williams
Sep 5 '06 #4

This thread has been closed and replies have been disabled. Please start a new discussion.

Similar topics

30
3464
by: Steven Bethard | last post by:
George Sakkis wrote: > "Steven Bethard" <steven.bethard@gmail.com> wrote: >> Dict comprehensions were recently rejected: >> http://www.python.org/peps/pep-0274.html >> The reason, of course, is that dict comprehensions don't gain you >> much at all over the dict() constructor plus a generator expression, >> e.g.: >> dict((i, chr(65+i)) for i in range(4)) > > Sure, but the same holds for list comprehensions: list(i*i for i in
4
3625
by: Drew | last post by:
I have a permission tracking app that I am working on, and I have made the insert page for it. I am having issues on how to prevent duplicates from getting entered. Currently the interface for the app has a mixture of select boxes, list boxes and checkboxes. The form submits the page to processAIMR.asp and then does the inserting. I am using a loop to insert a new record for each checkbox checked or listbox entry selected. My...
5
11454
by: Jani Yusef | last post by:
Based on an interview question I heard of but did not know the answer to....... How do you find and remove a loop from a singly linked list? In a google groups search I found the following code which will detect the loop but I am stumped how one would remove this loop. Any ideas? typedef enum { FALSE, TRUE } bool;
3
3113
by: Jeremy Owens-Boggs | last post by:
We are trying to implement a dual list box selection where you have two list boxes, You highlight items in the right side list box, click a button and this moves those items over to the left hand list box. The problem is that if there are many items selected (thousands), then removing the items from the right side list box takes for ever because we are removing them one at a time, which causes the listbox to re-index everything before we...
0
5409
by: Frawls | last post by:
Hi, This is concerned with System.Web.UI.WebControls.DropDownList I am having problems creating a method which will remove list items from a preloaded dropdownlist. This dropdown is loaded when the page loads and the items are pulled from a database. I want to create a method which is called on the page load and will remove certain items from the dropdown list. I want the method to loop
24
4383
by: RyanTaylor | last post by:
I have a final coming up later this week in my beginning Java class and my prof has decided to give us possible Javascript code we may have to write. Problem is, we didn't really cover JS and what we covered was within the last week of the class and all self taught. Our prof gave us an example of a Java method used to remove elements from an array: public void searchProcess() { int outIt=0;
17
2712
by: Eric_Dexter | last post by:
def simplecsdtoorc(filename): file = open(filename,"r") alllines = file.read_until("</CsInstruments>") pattern1 = re.compile("</") orcfilename = filename + "orc" for line in alllines: if not pattern1 print >>orcfilename, line I am pretty sure my code isn't close to what I want. I need to be able
5
1808
by: gnassar | last post by:
Essentially my problem is that .NET 2005 is removing my event handlers. There's no real special things about my project, it just continually removes them all. It starts on the open of a solution. The screen flashes and immediately I can undo something. I look at the undo list and it says designer generated code. When I undo it, all of my event handlers come back. This is a very annoying issue has anyone solved this problem? -G
7
2836
by: =?Utf-8?B?Sm9lbCBNZXJr?= | last post by:
I have created a custom class with both value type members and reference type members. I then have another custom class which inherits from a generic list of my first class. This custom listneeds to support cloning: Public Class RefClass Public tcp As TcpClient Public name As String End Class Public Class RefClassList Inherits List(Of RefClass) Implements ICloneable
0
8731
marktang
by: marktang | last post by:
ONU (Optical Network Unit) is one of the key components for providing high-speed Internet services. Its primary function is to act as an endpoint device located at the user's premises. However, people are often confused as to whether an ONU can Work As a Router. In this blog post, we’ll explore What is ONU, What Is Router, ONU & Router’s main usage, and What is the difference between ONU and Router. Let’s take a closer look ! Part I. Meaning of...
0
8649
by: Hystou | last post by:
Most computers default to English, but sometimes we require a different language, especially when relocating. Forgot to request a specific language before your computer shipped? No problem! You can effortlessly switch the default language on Windows 10 without reinstalling. I'll walk you through it. First, let's disable language synchronization. With a Microsoft account, language settings sync across devices. To prevent any complications,...
0
9081
jinu1996
by: jinu1996 | last post by:
In today's digital age, having a compelling online presence is paramount for businesses aiming to thrive in a competitive landscape. At the heart of this digital strategy lies an intricately woven tapestry of website design and digital marketing. It's not merely about having a website; it's about crafting an immersive digital experience that captivates audiences and drives business growth. The Art of Business Website Design Your website is...
0
8931
tracyyun
by: tracyyun | last post by:
Dear forum friends, With the development of smart home technology, a variety of wireless communication protocols have appeared on the market, such as Zigbee, Z-Wave, Wi-Fi, Bluetooth, etc. Each protocol has its own unique characteristics and advantages, but as a user who is planning to build a smart home system, I am a bit confused by the choice of these technologies. I'm particularly interested in Zigbee because I've heard it does some...
0
7819
agi2029
by: agi2029 | last post by:
Let's talk about the concept of autonomous AI software engineers and no-code agents. These AIs are designed to manage the entire lifecycle of a software development project—planning, coding, testing, and deployment—without human intervention. Imagine an AI that can take a project description, break it down, write the code, debug it, and then launch it, all on its own.... Now, this would greatly impact the work of software developers. The idea...
0
5904
by: conductexam | last post by:
I have .net C# application in which I am extracting data from word file and save it in database particularly. To store word all data as it is I am converting the whole word file firstly in HTML and then checking html paragraph one by one. At the time of converting from word file to html my equations which are in the word document file was convert into image. Globals.ThisAddIn.Application.ActiveDocument.Select();...
0
4408
by: TSSRALBI | last post by:
Hello I'm a network technician in training and I need your help. I am currently learning how to create and manage the different types of VPNs and I have a question about LAN-to-LAN VPNs. The last exercise I practiced was to create a LAN-to-LAN VPN between two Pfsense firewalls, by using IPSEC protocols. I succeeded, with both firewalls in the same network. But I'm wondering if it's possible to do the same thing, with 2 Pfsense firewalls...
1
3097
by: 6302768590 | last post by:
Hai team i want code for transfer the data from one system to another through IP address by using C# our system has to for every 5mins then we have to update the data what the data is updated we have to send another system
2
2395
muto222
by: muto222 | last post by:
How can i add a mobile payment intergratation into php mysql website.

By using Bytes.com and it's services, you agree to our Privacy Policy and Terms of Use.

To disable or enable advertisements and analytics tracking please visit the manage ads & tracking page.