Sorting a file with related lines

Wednesday, April 17, 2013 perl , perl-hashes , sort 0 Comments

I have a file in which first row contains the number and second row contains a statement associated with it and so on like the below example:

12
stat1 
18
stat2
15
stat3

I need to print the output like sorting in descending order of numbers along with the statement related to it. So that the output should look like:

Time = 18
Stat = stat2
Time = 15
Stat = stat3
Time = 12
Stat = stat1

Below is the perl command that I have written which does the needed thing.

perl -lne 'if(/^\d+/){$k=$_}
           else{$x{$k}=$_}
           END{ 
               for(sort {$b<=>$a} keys %x){ 
               print "time=$_\nStat=$x{$_}";}
           }' file
time=18
Stat=stat2
time=15
Stat=stat3
time=12
Stat=stat1

Note:Precondition is time will come first and then the statement associated with it. 
Below is the explanation.

1. So store in a variable $k if the line start with a decimal point number.
2. Else case it is nothing but the statement. So store this line as a value to the previous stored $k.
   After parsing complete file.sort the keys of the hash in descending order by
3. sort  $b<=>$a and then print each and ever key and value in needed format.

Also please note:

1. sort $a<=>$b will sort the numbers in ascending order.
2. sort $b<=>$a will sort the numbers in descending order