Arjen Markus (13 january 2003) I have been experimenting with Metakit as a convenient package to store measurement data (of course this was the original design goal of Metakit, as Jean-Claude Wippler has told me), but still getting some feeling for working with such a database pacakge is worthwhile.
The script below (slightly adapted from the original) creates a database from a simple data file and does some basic statistical analysis.
The performance is quite acceptable to me:
The platform:
Intel Pentium II, 350 MHz Windows 98 tclkit, downloaded 3 july 2002
The data file:
Simple text file, 1.7 MB 44000 lines each containing 9 integers
The results:
11 seconds for reading the data file and creating the database
11 seconds for retrieving 4 columns of 44000 data each and
determining basic statistical properties
resulting database is 0.9 MB
about 80 lines of code # testdata.tcl --
#
# Create a Metakit database and perform some simple statistical
# tests
#
# version 0.1: initial implementation, january 2003
package require Mk4tcl
source statistics.tcl
# fillDatabase
# Fill the database with the contents of a tabular file
#
# Arguments:
# db Opened database
# input Name of the input file
#
# Result:
# Name of table (view) that was created
#
proc fillDatabase { db input } {
set table [mk::view layout $db.table \
{date a:F b:F c:F d:F}]
set infile [open $input "r"]
# Skip header
gets $infile line
while { [gets $infile line] > -1 } {
foreach {dummy yy mm dd hh a b c d} $line {break}
set date [format "19%2.2d%2.2d%2.2d%2.2d" $yy $mm $dd $hh]
mk::row append $table date $date a $a \
b $b c $c d $d
}
close $infile
mk::file commit $db
return $table
}
# getColumn --
# Return a list consisting of the given column
#
# Arguments:
# table Table or view to retrieve
# colname Name of the column
#
# Results:
# List of values
#
proc getColumn { table colname } {
set result {}
mk::loop c $table {
lappend result [mk::get $c $colname]
}
return $result
}
# main --
# Main code
#
console show
mk::file open db "mydata.tkd"
set table [fillDatabase db [file join .. "myfile.dat"]]
set table "db.table"
foreach col {a b c d} {
set result [getColumn $table $col]
puts "$col: [::math::statistics::basicStats $result]"
}
mk::file close db