Dbmultistats (1) Linux Manual Page

dbmultistats – run dbcolstats over each group of inputs identified by some key

Synopsis

$0 [-dm] [-c ConfidencePercent] [-f FormatForm] [-q NumberOfQuartiles] -k KeyField ValueField

Description

The input table is grouped by KeyField, then we compute a separate set of column statistics on ValueField for each group with a unique key.

Assumptions and requirements are the same as dbmapreduce (this program is just a wrapper around that program):

By default, data can be provided in arbitrary order and the program consumes O(number of unique tags) memory, and O(size of data) disk space.

With the -S option, data must arrive group by tags (not necessarily sorted), and the program consumes O(number of tags) memory and no disk space. The program will check and abort if this precondition is not met.

With two -S’s, program consumes O(1) memory, but doesn’t verify that the data-arrival precondition is met.

(Note that these semantics are exactly like
dbmapreduce -k KeyField — dbcolstats ValueField dbmultistats provides a simpler API that passes through statistics-specific arguments and is optimized when data is pre-sorted and there are no quarties or medians.)

Options

Options are the same as dbcolstats.

-k or –key KeyField: specify which column is the key for grouping (default: the first column)
-a or –include-non-numeric: Compute stats over all records (treat non-numeric records as zero rather than just ignoring them).
-c FRACTION or –confidence FRACTION: Specify FRACTION for the confidence interval. Defaults to 0.95 for a 95% confidence factor.
-f FORMAT or –format FORMAT: Specify a printf(3)-style format for output statistics. Defaults to "%.5g".
-m or –median: Compute median value. (Will sort data if necessary.) (Median is the quantitle for N=2.)
-q N or –quantile N: Compute quantile (quartile when N is 4), or an arbitrary quantile for other values of N, where the scores that are 1 Nth of the way across the population.
-S or –pre-sorted: Assume data is already sorted. With one -S, we check and confirm this precondition. When repeated, we skip the check.
<-T TmpDir>: where to put temporary data. Only used if median or quantiles are requested. Also uses environment variable TMPDIR, if -T is not specified. Default is /tmp.
<–parallelism=N>: Allow up to N reducers to run in parallel. Default is the number of CPUs in the machine.

This module also supports the standard fsdb options:

-d: Enable debugging output.
-i or –input InputSource: Read from InputSource, typically a file name, or "-" for standard input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.
-o or –output OutputDestination: Write to OutputDestination, typically a file name, or "-" for standard output, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue objects.
–autorun or –noautorun: By default, programs process automatically, but Fsdb::Filter objects in Perl do not run until you invoke the run() method. The "–(no)autorun" option controls that behavior within Perl.
–help: Show help.
–man: Show full manual.

Sample Usage

Input:

 #fsdb experiment duration

 ufs_mab_sys 37.2

 ufs_mab_sys 37.3

 ufs_rcp_real 264.5

 ufs_rcp_real 277.9

Command:

 cat DATA/stats.fsdb | dbmultistats -k experiment duration

Output:

 #fsdb experiment mean stddev pct_rsd conf_range conf_low conf_high conf_pct sum sum_squared min max n

 ufs_mab_sys 37.25 0.070711 0.18983 0.6353 36.615 37.885 0.95 74.5 2775.1 37.2 37.3 2

 ufs_rcp_real 271.2 9.4752 3.4938 85.13 186.07 356.33 0.95 542.4 1.4719e+05 264.5 277.9 2

 # | /home/johnh/BIN/DB/dbmultistats experiment duration

AUTHOR and COPYRIGHT

This program is distributed under terms of the GNU general public license, version 2. See the file COPYING with the distribution for details.

dbmultistats (1) Linux Manual Page