473,389 Members | 1,355 Online
Bytes | Software Development & Data Engineering Community
Post Job

Home Posts Topics Members FAQ

Join Bytes to post your question to a community of 473,389 software developers and data experts.

Sorting array



Hi,
I'm working with numerical array and I'm a little lost on a particular
sorting of one of them. In particular I have an array like

a = array([[8,4,1],[2,0,9]])

and I need to sort it using only the first column as reference but
keeping the lines together so to obtain

array([[2, 0, 9],
[8, 4, 1]])

Any help?
Thanks
Nov 30 '07 #1
5 2115
the list.sort method seems to do exactly what you want?

Unless your array() method is creating a custom array object with
different sort functionality than list?

Cheers
Nov 30 '07 #2
Chris Hulan wrote:
the list.sort method seems to do exactly what you want?

Unless your array() method is creating a custom array object with
different sort functionality than list?
Presumably he is using numpy arrays.

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco

Nov 30 '07 #3
Tartifola wrote:
>
Hi,
I'm working with numerical array and I'm a little lost on a particular
sorting of one of them. In particular I have an array like

a = array([[8,4,1],[2,0,9]])

and I need to sort it using only the first column as reference but
keeping the lines together so to obtain

array([[2, 0, 9],
[8, 4, 1]])
In [1]: from numpy import *

In [2]: a = array([[8,4,1],[2,0,9]])

In [3]: i = argsort(a[:,0])

In [4]: a[i]
Out[4]:
array([[2, 0, 9],
[8, 4, 1]])
numpy questions are best asked on the numpy-discussion mailing list since
everyone there automatically knows that you are talking about numpy arrays and
not just misnaming lists. ;-)

http://www.scipy.org/Mailing_Lists

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco

Nov 30 '07 #4


Hi,

On Fri, 30 Nov 2007 14:55:08 -0600
Robert Kern <ro*********@gmail.comwrote:
Tartifola wrote:

Hi,
I'm working with numerical array and I'm a little lost on a particular
sorting of one of them. In particular I have an array like

a = array([[8,4,1],[2,0,9]])

and I need to sort it using only the first column as reference but
keeping the lines together so to obtain

array([[2, 0, 9],
[8, 4, 1]])

In [1]: from numpy import *

In [2]: a = array([[8,4,1],[2,0,9]])

In [3]: i = argsort(a[:,0])

In [4]: a[i]
Out[4]:
array([[2, 0, 9],
[8, 4, 1]])
numpy questions are best asked on the numpy-discussion mailing list since
everyone there automatically knows that you are talking about numpy arrays and
not just misnaming lists. ;-)

http://www.scipy.org/Mailing_Lists
thanks a lot for your help and sorry for using the wrong list.

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
Dec 1 '07 #5
Tartifola wrote:
>
Hi,

On Fri, 30 Nov 2007 14:55:08 -0600
Robert Kern <ro*********@gmail.comwrote:
>numpy questions are best asked on the numpy-discussion mailing list since
everyone there automatically knows that you are talking about numpy arrays and
not just misnaming lists. ;-)

http://www.scipy.org/Mailing_Lists

thanks a lot for your help and sorry for using the wrong list.
No need to apologize. This isn't the wrong list; it's just that there is a
better list. :-)

--
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco

Dec 1 '07 #6

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

Similar topics

3
by: Paul Kirby | last post by:
Hello All I am trying to update me code to use arrays to store a group of information and I have come up with a problem sorting the multiple array :( Array trying to sort: (7 arrays put into...
7
by: Federico G. Babelis | last post by:
Hi All: I have this line of code, but the syntax check in VB.NET 2003 and also in VB.NET 2005 Beta 2 shows as unknown: Dim local4 As Byte Fixed(local4 = AddressOf dest(offset)) ...
3
by: SilverWolf | last post by:
I need some help with sorting and shuffling array of strings. I can't seem to get qsort working, and I don't even know how to start to shuffle the array. Here is what I have for now: #include...
7
by: Foodbank | last post by:
Hi everyone. I'm having trouble with this radix sorting program. I've gotten some of it coded except for the actual sorting :( The book I'm teaching myself with (Data Structures Using C and...
0
by: Brian Henry | last post by:
Here is another virtual mode example for the .NET 2.0 framework while working with the list view. Since you can not access the items collection of the list view you need to do sorting another...
7
by: Kamal | last post by:
Hello all, I have a very simple html table with collapsible rows and sorting capabilities. The collapsible row is hidden with css rule (display:none). When one clicks in the left of the...
5
KevinADC
by: KevinADC | last post by:
Introduction This discussion of the sort function is targeted at beginners to perl coding. More experienced perl coders will find nothing new or useful. Sorting lists or arrays is a very common...
1
KevinADC
by: KevinADC | last post by:
Introduction In part one we discussed the default sort function. In part two we will discuss more advanced techniques you can use to sort data. Some of the techniques might introduce unfamiliar...
5
by: lemlimlee | last post by:
hello, this is the task i need to do: For this task, you are to develop a Java program that allows a user to search or sort an array of numbers using an algorithm that the user chooses. The...
5
by: jrod11 | last post by:
hi, I found a jquery html table sorting code i have implemented. I am trying to figure out how to edit how many colums there are, but every time i remove code that I think controls how many colums...
0
by: taylorcarr | last post by:
A Canon printer is a smart device known for being advanced, efficient, and reliable. It is designed for home, office, and hybrid workspace use and can also be used for a variety of purposes. However,...
0
by: Charles Arthur | last post by:
How do i turn on java script on a villaon, callus and itel keypad mobile phone
0
by: ryjfgjl | last post by:
In our work, we often receive Excel tables with data in the same format. If we want to analyze these data, it can be difficult to analyze them because the data is spread across multiple Excel files...
0
by: emmanuelkatto | last post by:
Hi All, I am Emmanuel katto from Uganda. I want to ask what challenges you've faced while migrating a website to cloud. Please let me know. Thanks! Emmanuel
0
by: Hystou | last post by:
There are some requirements for setting up RAID: 1. The motherboard and BIOS support RAID configuration. 2. The motherboard has 2 or more available SATA protocol SSD/HDD slots (including MSATA, M.2...
0
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,...
0
Oralloy
by: Oralloy | last post by:
Hello folks, I am unable to find appropriate documentation on the type promotion of bit-fields when using the generalised comparison operator "<=>". The problem is that using the GNU compilers,...
0
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...
0
by: Hystou | last post by:
Overview: Windows 11 and 10 have less user interface control over operating system update behaviour than previous versions of Windows. In Windows 11 and 10, there is no way to turn off the Windows...

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.