sorting array 
Author Message
 sorting array

Greets,
before some time I read in this newsgroup the following snippet:

!a[$0]++   ;remove duplicated rows

so I used it for making array without duplicates:

Input: "zzz", "xxx", "yyy", "xxx", "zzz" etc
Output: array -> ["zzz","xxx","yyy"]

Problem: How to sort array with uniq strings?
Target array: ["xxx","yyy","zzz"]

Best Regards,
Sto



Sat, 08 Feb 2003 20:57:31 GMT  
 sorting array

Quote:

> !a[$0]++   ;remove duplicated rows
> so I used it for making array without duplicates
> ...

That's a nice and tricky awk solution, but in the real world
one would use the system sort command with the 'unique keys'
switch, whichever it be (in unix  sort -u)

Quote:
> Problem: How to sort array with uniq strings?

The real world solution is to use external system sort command.

Another possible dirty solution is to make a function to build
a 'sort map' array (indexed by ordinal number) of the first
array (indexed by string key):

...
# mysortmap() builds ordered array oo[bumbers] from array
# aa[keys] and returns the number of elements in n
...
  n = mysortmap(oo,aa)
...
  for(i = 1; i <= n; i++) {
    k = oo[i]
    ...
    print aa[k]  # for example...
    ...
  }
...

function mysortmap(oo,aa,   n,i,j,k)
{
  # build a 'sort map' ordered array
  n = 0
# fill in keys and count them
  for(k in aa) {
    oo[++n] = k
  }
# silly sort with two nested loops
  for(i = 1; i <= n -1; i++) {
    k = i
    for(j = i+1; j <= n; j++) { # fetch lowest element index k
      if(oo[j] < oo[k]) k = j
    }
    if(k > i) { # swap k,i
      j = oo[k]
      oo[k] = oo[i]
      oo[i] = j
    }
  }
  return n

Quote:
}

--
  All true believers shall break their eggs at the convenient end.



Sat, 08 Feb 2003 03:00:00 GMT  
 
 [ 2 post ] 

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