On Jun 14, 12:00 pm, jim-on-linux <[EMAIL PROTECTED]> wrote:
> 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
Here's another way to attack it. Make a class that takes your columns
as arguments. define an operator on that class to get the comparison
you want. make a list that is your rows, and call sort. here's an
example using only two columns
class twoColumns :
def __init__(self, c1 = 0, c2 = 0) :
self.c1 = c1
self.c2 = c2
#just use this for debugging if you want to see everything
def getVals(self):
print self.c1, self.c2
#order members of this class by the second column
def __lt__(c,d):
if (c.c2 < d.c2) :
return 1
else :
return 0
#end class definition
Here's what happened when I used this class.
>>> r1 = twoColumns(3,4)
>>> r2 = twoColumns(1,5)
>>> test = [r1,r2] #this is already sorted
>>> test[0].getVals()
3 4
>>> test[1].getVals()
1 5
>>> test.sort() #and the sort looks the same
>>> test[0].getVals()
3 4
>>> test[1].getVals()
1 5
>>> test = [r2,r1] #I reversed the rows
>>> test[0].getVals()
1 5
>>> test[1].getVals()
3 4
>>> test.sort() #and we get what we want
>>> test[0].getVals()
3 4
>>> test[1].getVals()
1 5
I think that does what you're asking.
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