473,545 Members | 1,878 Online
Bytes | Software Development & Data Engineering Community
+ Post

Home Posts Topics Members FAQ

Re: sorting a file

On Saturday 14 June 2008 03:15, Beema
shafreen wrote:
Hi all,

I have a file with three columns i need
to sort the file with respect to the third
column. How do I do it uisng python. I
used Linux command to do this. Sort but i
not able to do it ? can any body ssuggest
me

I have used this method to solve similar
problems.

This is a consept of how to do what you want,
but you will have to work a little to get it
right.

You might try something like this;

Dict = {} ##create a dictionary

make a list of all column3 values

for loop colum3 values

Make these values the key in a dictionary
If the values are long, you can use the first
7 to 15 characters if you want.

use this key to equal all the values in the
other columns on the same row.

Dict[column3] = column1, column2, column3

once the dictionary is made

get the dictionary key
x = Dict.keys() ## get the keys from Dict
x.sort() # produce a sorted list of keys of
column3

Loop these sorted keys to extract from the
dictionary the values related to each
jim-on-linux
http://:inqvista.com





Jun 27 '08 #1
1 1492
On Jun 15, 2:00 am, jim-on-linux <inq1...@inqvis ta.comwrote:
On Saturday 14 June 2008 03:15, Beema

shafreen wrote:
Hi all,
I have a file with three columns i need
to sort the file with respect to the third
column. How do I do it uisng python. I
used Linux command to do this. Sort but i
not able to do it ? can any body ssuggest
me

I have used this method to solve similar
problems.

This is a consept of how to do what you want,
but you will have to work a little to get it
right.

You might try something like this;

Dict = {} ##create a dictionary

make a list of all column3 values
Ummm this appears somewhat baroque .... try this:

Assuming the OP has arranged to read his data into a list of lists
"filedata" such that filedata[-1][2] is the data in the 3rd column of
the last row. Further assume that the data has just been read with
e.g. the csv module so all data is still in text form and may need
some conversion before comparison (otherwise e.g. a salary of 100000
would appear before a salary of 99999).

Suppose the 3rd column is a salary, without '$' and ',' in it.

Now let's look at the manual for the sort method. It gives us 2
options: a cmp function and a key function, with a strong hint that
key is better. So for each row, what do we want on sort on? It's the
numerical value of the 3rd item:

def sort_key_func(r ow):
return float(row[2])

Then we can simply do:
filedata.sort(k ey=sort_key_fun c)

All that remains is to write the contents of filedata to the output
file.

HTH,
John
Jun 27 '08 #2

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

Similar topics

6
10881
by: bissatch | last post by:
Hi, I am about to write an application that will display all pdf files in a folder and display them by file name in order of date. Is there an easy way of doing this? I was thinking about somehow adding filename and date created in an array, sorting by date and then printing onto an html page with a link to that file. How would I do this...
5
1403
by: Lad | last post by:
Hi, I have a file of records of 4 fields each. Each field is separated by a semicolon. That is Filed1;Ffield2;Field3;Field4 But there may be also empty records such as ;;;; (only semicolons).
22
4122
by: mike | last post by:
If I had a date in the format "01-Jan-05" it does not sort properly with my sort routine: function compareDate(a,b) { var date_a = new Date(a); var date_b = new Date(b); if (date_a < date_b) { return -1; } else
20
4030
by: Xah Lee | last post by:
Sort a List Xah Lee, 200510 In this page, we show how to sort a list in Python & Perl and also discuss some math of sort. To sort a list in Python, use the “sort” method. For example: li=;
25
2193
by: Dan Stromberg | last post by:
Hi folks. Python appears to have a good sort method, but when sorting array elements that are very large, and hence have very expensive compares, is there some sort of already-available sort function that will merge like elements into a chain, so that they won't have to be recompared as many times? Thanks!
7
4803
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 expandable row, the hidden row is made visible with css. The problem is when i sort the rows, the hidden rows get sorted as well which i don't want and want...
3
2180
by: SneakyElf | last post by:
i am very green with c++ so i get stuck on very simple things anyway, i need to write a program that would read data from file (containing names of tv shows and their networks) one line at a time ( ; separates tv show and network) sort the strings according to the network and according to the show. and so: //to open file - ifstream...
1
4139
by: =?Utf-8?B?YmJkb2J1ZGR5?= | last post by:
I have a grid view that pulls data from a dbf file. I set the Allow Sorting to true and I put my code in the Sorting event. The problem is that I can't get the sorting to work so I wrote some info to a text file to see what is happening. What I found out is that when I clicked on a column to sort it the Sorting function was continuously...
3
7308
KevinADC
by: KevinADC | last post by:
If you are entirely unfamiliar with using Perl to sort data, read the "Sorting Data with Perl - Part One and Two" articles before reading this article. Beginning Perl coders may find this article uses unfamiliar terms and syntax. Intermediate and advanced Perl coders should find this article useful. The object of the article is to inform the...
5
4910
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 there are, it crashes. There are currently 6 columns, and I only want 4. How do I remove the last two (discount and date)? Here is a link:...
0
7643
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, it seems that the internal comparison operator "<=>" tries to promote arguments from unsigned to signed. This is as boiled down as I can make it. ...
0
7798
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...
1
7405
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 Update option using the Control Panel or Settings app; it automatically checks for updates and installs any it finds, whether you like it or not. For...
1
5316
isladogs
by: isladogs | last post by:
The next Access Europe User Group meeting will be on Wednesday 1 May 2024 starting at 18:00 UK time (6PM UTC+1) and finishing by 19:30 (7.30PM). In this session, we are pleased to welcome a new presenter, Adolph Dupr who will be discussing some powerful techniques for using class modules. He will explain when you may want to use classes...
0
4938
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...
0
3441
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...
0
3436
by: adsilva | last post by:
A Windows Forms form does not have the event Unload, like VB6. What one acts like?
1
1862
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
1
1004
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.