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Full Discussion: Matrix to 3 col sorted
Top Forums Shell Programming and Scripting Matrix to 3 col sorted Post 303003886 by ctsgnb on Friday 22nd of September 2017 06:08:49 AM
Old 09-22-2017
Whatever strategy you choose, according to your expectation, you will get an output file that is near 5 times bigger than your input file.

input file :
rows = 400k
columns = 3000
Total amount of datas = 400k x 3000 = 1,2 billions

output file :
rows = (400k -1) x ( 3000 -3 )
"-1" because of the header row
"-3" because the 3 first contains the datas you want
columns = 5 (i take into account the datas, not the formatting and "__" stuff)
Total amount of datas = 5 x (400k -1) x ( 3000 -3 ) = 5,99...billions

Indeed, since you will be repeating the datas of the first 3 column for each and every subsequent column. (so (3 + 2 ) x (3000 - 3) ) rather than having it once for all of them ( "+ 2" is because you even want to add the header and the values of the subsequent column).

So just because of your prerequisits and expectations, for sure you will have to write more data, and thus you will need the corresponding number of I/O writing, independently of the strategy you choose.

If you have a huge amount of data to write, then there is and uncompressible amount of time to do it.
Of course I/O operations are quicker to do in RAM or SSD than on a standard hard drive, but still ...

It would be cheaper to save the transposed matrix and request on it
So you will have it twice : in line and in columns ... of course it will cost you 1,2 billions of datas more.
But 1,2 billions x 2 = 2,4 billions is still more than twice smaller than 5,9 billions of datas !

Anyway, processing such an amount of data using files is inappropriate : this is what Database have been designed for...
My 2 cents ...

Smilie

PS// The reality might even be worse since i didn't even take into account the size of the datas, just the number of them ...

Last edited by ctsgnb; 09-22-2017 at 12:18 PM..
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Table(3)						User Contributed Perl Documentation						  Table(3)

NAME
Tk::Table - Scrollable 2 dimensional table of Tk widgets SYNOPSIS
use Tk::Table; $table = $parent->Table(-rows => number, -columns => number, -scrollbars => anchor, -fixedrows => number, -fixedcolumns => number, -takefocus => boolean); $widget = $table->Button(...); $old = $table->put($row,$col,$widget); $old = $table->put($row,$col,"Text"); # simple Label $widget = $table->get($row,$col); $cols = $table->totalColumns; $rows = $table->totalRows; $table->see($widget); $table->see($row,$col); ($row,$col) = $table->Posn($widget); DESCRIPTION
Tk::Table is an all-perl widget/geometry manager which allows a two dimensional table of arbitary perl/Tk widgets to be displayed. Entries in the Table are simply ordinary perl/Tk widgets. They should be created with the Table as their parent. Widgets are positioned in the table using: $table->put($row,$col,$widget) If $widget is not a reference it is treated as a string, and a Lable widget is created with the string as its text. All the widgets in each column are set to the same width - the requested width of the widest widget in the column. Likewise, all the widgets in each row are set to the same height - the requested height of the tallest widget in the column. A number of rows and/or columns can be marked as 'fixed' - and so can serve as 'headings' for the remainder the rows which are scrollable. The requested size of the table as a whole is such that the number of rows specified by -rows (default 10), and number of columns specified by -columns (default 10) can be displayed. If the Table is told it can take the keyboard focus then cursor and scroll keys scroll the displayed widgets. The Table will create and manage its own scrollbars if requested via -scrollbars. The table can be emptied using $table->clear the widgets which were in the table are destroyed. The Tk::Table widget is derived from a Tk::Frame, so inherits all its configure options. BUGS
/ Snags / Possible enhancements o Very large Tables consume a lot of X windows. o No equivalent of pack's -anchor/-pad etc. options SEE ALSO
Tk::grid, Tk::HList, Tk::TableMatrix, Tk::MListbox, Tk::Columns perl v5.12.1 2007-11-08 Table(3)
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