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Full Discussion: Question about grep
Top Forums Shell Programming and Scripting Question about grep Post 302619573 by methyl on Thursday 5th of April 2012 05:09:22 PM
Old 04-05-2012
sed 'q' bigfile | grep "string"
Nice post. Been looking for that one for a long time.

Any way of reading just the first line of a big file quickly is really useful. This has to be the shortest code.

Not so sure about this one because it searches the entire file if the string is not found:
sed '/string/!d;q' bigfile


For a 600 Mb text file:
Code:
time sed 'q' bigfile | grep "string"

real        0.0
user        0.0
sys         0.0

time sed '/string/!d;q' bigfile

real       47.7
user       39.2
sys         8.4


Last edited by methyl; 04-05-2012 at 06:18 PM..
This User Gave Thanks to methyl For This Post:
 

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Bio::Structure::Atom(3pm)				User Contributed Perl Documentation				 Bio::Structure::Atom(3pm)

NAME
Bio::Structure::Atom - Bioperl structure Object, describes an Atom SYNOPSIS
#add synopsis here DESCRIPTION
This object stores a Bio::Structure::Atom FEEDBACK
Mailing Lists User feedback is an integral part of the evolution of this and other Bioperl modules. Send your comments and suggestions preferably to one of the Bioperl mailing lists. Your participation is much appreciated. bioperl-l@bioperl.org - General discussion http://bioperl.org/wiki/Mailing_lists - About the mailing lists Support Please direct usage questions or support issues to the mailing list: bioperl-l@bioperl.org rather than to the module maintainer directly. Many experienced and reponsive experts will be able look at the problem and quickly address it. Please include a thorough description of the problem with code and data examples if at all possible. Reporting Bugs Report bugs to the Bioperl bug tracking system to help us keep track the bugs and their resolution. Bug reports can be submitted via the web: https://redmine.open-bio.org/projects/bioperl/ AUTHOR - Kris Boulez Email kris.boulez@algonomics.com APPENDIX
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _ new() Title : new() Usage : $struc = Bio::Structure::Atom->new( -id => 'human_id', ); Function: Returns a new Bio::Structure::Atom object from basic constructors. Probably most called from Bio::Structure::IO. Returns : a new Bio::Structure::Atom object x() Title : x Usage : $x = $atom->x($x); Function: Set/gets the X coordinate for an Atom Returns : The value for the X coordinate of the Atom (This is just a number, it is expected to be in Angstrom, but no garantees) Args : The X coordinate as a number y() Title : y Usage : $y = $atom->y($y); Function: Set/gets the Y coordinate for an Atom Returns : The value for the Y coordinate of the Atom (This is just a number, it is eypected to be in Angstrom, but no garantees) Args : The Y coordinate as a number z() Title : z Usage : $z = $atom->z($z); Function: Set/gets the Z coordinate for an Atom Returns : The value for the Z coordinate of the Atom (This is just a number, it is ezpected to be in Angstrom, but no garantees) Args : The Z coordinate as a number xyz() Title : xyz Usage : ($x,$y,$z) = $atom->xyz; Function: Gets the XYZ coordinates for an Atom Returns : A list with the value for the XYZ coordinate of the Atom Args : residue() Title : residue Usage : Function: No code here, all parent/child stuff via Entry Returns : Args : icode() Title : icode Usage : $icode = $atom->icode($icode) Function: Sets/gets the icode Returns : Returns the icode for this atom Args : reference to an Atom serial() Title : serial Usage : $serial = $atom->serial($serial) Function: Sets/gets the serial number Returns : Returns the serial number for this atom Args : reference to an Atom occupancy() Title : occupancy Usage : $occupancy = $atom->occupancy($occupancy) Function: Sets/gets the occupancy Returns : Returns the occupancy for this atom Args : reference to an Atom tempfactor() Title : tempfactor Usage : $tempfactor = $atom->tempfactor($tempfactor) Function: Sets/gets the tempfactor Returns : Returns the tempfactor for this atom Args : reference to an Atom segID() Title : segID Usage : $segID = $atom->segID($segID) Function: Sets/gets the segID Returns : Returns the segID for this atom Args : reference to an Atom pdb_atomname() Title : pdb_atomname Usage : $pdb_atomname = $atom->pdb_atomname($pdb_atomname) Function: Sets/gets the pdb_atomname (atomname used in the PDB file) Returns : Returns the pdb_atomname for this atom Args : reference to an Atom element() Title : element Usage : $element = $atom->element($element) Function: Sets/gets the element Returns : Returns the element for this atom Args : reference to an Atom charge() Title : charge Usage : $charge = $atom->charge($charge) Function: Sets/gets the charge Returns : Returns the charge for this atom Args : reference to an Atom sigx() Title : sigx Usage : $sigx = $atom->sigx($sigx) Function: Sets/gets the sigx Returns : Returns the sigx for this atom Args : reference to an Atom sigy() Title : sigy Usage : $sigy = $atom->sigy($sigy) Function: Sets/gets the sigy Returns : Returns the sigy for this atom Args : reference to an Atom sigz() Title : sigz Usage : $sigz = $atom->sigz($sigz) Function: Sets/gets the sigz Returns : Returns the sigz for this atom Args : reference to an Atom sigocc() Title : sigocc Usage : $sigocc = $atom->sigocc($sigocc) Function: Sets/gets the sigocc Returns : Returns the sigocc for this atom Args : reference to an Atom sigtemp() Title : sigtemp Usage : $sigtemp = $atom->sigtemp($sigtemp) Function: Sets/gets the sigtemp Returns : Returns the sigtemp for this atom Args : reference to an Atom aniso() Title : aniso Usage : $u12 = $atom->aniso("u12", $u12) Function: Sets/gets the anisotropic temperature factors Returns : Returns the requested factor for this atom Args : reference to an Atom, name of the factor, value for the factor id() Title : id Usage : $atom->id("CZ2") Function: Gets/sets the ID for this atom Returns : the ID Args : the ID _remove_residue() Title : _remove_residue Usage : Function: Removes the Residue this Atom is atttached to. Returns : Args : _grandparent() Title : _grandparent Usage : Function: get/set a symbolic reference to our grandparent Returns : Args : perl v5.14.2 2012-03-02 Bio::Structure::Atom(3pm)
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