01-10-2010
Quote:
Originally Posted by
uiop44
I have two very large datasets (>100MB) in a simple vertical list format. They are of different size and with different order and formatting (e.g. whitespace and some other minor cruft that would thwart easy regex).
Let's call them set1 and set2.
I want to check set2 to see if it contains any of the data entries in set1. I think of this as individual greps of set2 using each line of set1.
(NB- I could, with some work, manipulate the sets to make the order and formatting the same.)
In your opinion, what is the best tool to use for this search of set2 using the data in set1?
- comm?
- a looping shell script, or xargs, that calls grep?
- grep -f?
- diff?
- combine the sets (after making format the same) then sort and print only duplicate lines? uniq -d, sed or awk
I would implement them like this ->
1. sort both the datasets (presorting always helps for better performance especially if the datasets needs to be updated frequently and the operation is carried out many times.
2.Lets say set1 has index1 and set2 has index2
3.add a very large element say 10000000(which is larger than the largest of the elements in set1 and set2) to set1. See below why.
4. while not(end of set2) // set2 is the bottleneck
{ print set2[index2] if set1[index1]==set2[index2];
index2++ if(set2[index2]<set1[index1])
index1++ if(set2[index1]>set1[index1])
}
P.S . we added it to exhaust set2 which is the condition of the while loop. However you could have done while not(end of set1) And not(end of set2) {} but since you only wanna check set2 so we had to stick to above to make it more efficient.
enjoy,
Gaurav
Last edited by gaurav1086; 01-10-2010 at 07:17 AM..
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LEARN ABOUT SUSE
struct_set
struct::set(n) Tcl Data Structures struct::set(n)
__________________________________________________________________________________________________________________________________________________
NAME
struct::set - Procedures for manipulating sets
SYNOPSIS
package require Tcl 8.0
package require struct::set ?2.2.3?
::struct::set empty set
::struct::set size set
::struct::set contains set item
::struct::set union ?set1...?
::struct::set intersect ?set1...?
::struct::set difference set1 set2
::struct::set symdiff set1 set2
::struct::set intersect3 set1 set2
::struct::set equal set1 set2
::struct::set include svar item
::struct::set exclude svar item
::struct::set add svar set
::struct::set subtract svar set
::struct::set subsetof A B
_________________________________________________________________
DESCRIPTION
The ::struct::set namespace contains several useful commands for processing finite sets.
It exports only a single command, struct::set. All functionality provided here can be reached through a subcommand of this command.
Note: As of version 2.2 of this package a critcl based C implementation is available. This implementation however requires Tcl 8.4 to run.
COMMANDS
::struct::set empty set
Returns a boolean value indicating if the set is empty (true), or not (false).
::struct::set size set
Returns an integer number greater than or equal to zero. This is the number of elements in the set. In other words, its cardinality.
::struct::set contains set item
Returns a boolean value indicating if the set contains the element item (true), or not (false).
::struct::set union ?set1...?
Computes the set containing the union of set1, set2, etc., i.e. "set1 + set2 + ...", and returns this set as the result of the com-
mand.
::struct::set intersect ?set1...?
Computes the set containing the intersection of set1, set2, etc., i.e. "set1 * set2 * ...", and returns this set as the result of
the command.
::struct::set difference set1 set2
Computes the set containing the difference of set1 and set2, i.e. ("set1 - set2") and returns this set as the result of the command.
::struct::set symdiff set1 set2
Computes the set containing the symmetric difference of set1 and set2, i.e. ("(set1 - set2) + (set2 - set1)") and returns this set
as the result of the command.
::struct::set intersect3 set1 set2
This command is a combination of the methods intersect and difference. It returns a three-element list containing "set1*set2",
"set1-set2", and "set2-set1", in this order. In other words, the intersection of the two parameter sets, and their differences.
::struct::set equal set1 set2
Returns a boolean value indicating if the two sets are equal (true) or not (false).
::struct::set include svar item
The element item is added to the set specified by the variable name in svar. The return value of the command is empty. This is the
equivalent of lappend for sets. If the variable named by svar does not exist it will be created.
::struct::set exclude svar item
The element item is removed from the set specified by the variable name in svar. The return value of the command is empty. This is a
near-equivalent of lreplace for sets.
::struct::set add svar set
All the element of set are added to the set specified by the variable name in svar. The return value of the command is empty. This
is like the method include, but for the addition of a whole set. If the variable named by svar does not exist it will be created.
::struct::set subtract svar set
All the element of set are removed from the set specified by the variable name in svar. The return value of the command is empty.
This is like the method exclude, but for the removal of a whole set.
::struct::set subsetof A B
Returns a boolean value indicating if the set A is a true subset of or equal to the set B (true), or not (false).
REFERENCES
BUGS, IDEAS, FEEDBACK
This document, and the package it describes, will undoubtedly contain bugs and other problems. Please report such in the category struct
:: set of the Tcllib SF Trackers [http://sourceforge.net/tracker/?group_id=12883]. Please also report any ideas for enhancements you may
have for either package and/or documentation.
KEYWORDS
cardinality, difference, emptiness, exclusion, inclusion, intersection, membership, set, symmetric difference, union
COPYRIGHT
Copyright (c) 2004-2008 Andreas Kupries <andreas_kupries@users.sourceforge.net>
struct 2.2.3 struct::set(n)