1DBCOLHISTO(1)         User Contributed Perl Documentation        DBCOLHISTO(1)
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NAME

6       dbcolhisto - compute a histogram over a column of Fsdb data
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SYNOPSIS

9       dbcolhisto [-ag] [-W BucketWidth] [-S BucketStart] [-E BucketEnd] [-N
10       NumberOfBuckets] column
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DESCRIPTION

13       This program computes a histogram over a column of data.  Records
14       containing non-numeric data are considered null do not contribute to
15       the stats (optionally they are treated as zeros).
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17       Defaults to 10 buckets over the exact range of data.  Up to three
18       parameters (number of buckets, start, end, and width) can be specified,
19       the rest default accordingly.
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21       Buckets range from a value (given the the low column) to just below the
22       next low value and buckets are equal width.  If necessary, extra "<min"
23       and ">max" buckets are created.  By default, the last bucket includes
24       max (and is thus infinitesimally larger than the other buckets).  This
25       irregularity can be removed with the "-I" option.
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27       This program requires O(number of buckets) memory and O(size of data)
28       temporary disk space.
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OPTIONS

31       -W or --width N
32           Gives with width of each bucket, in data units.  Default is
33           whatever gives 10 buckets over the whole range of data.
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35       -S or --start N
36           Buckets start at value N, in data units.  Default is the minimum
37           data value.
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39       -E or --end N
40           Buckets end at value N, in data units.  Default is the maximum data
41           value.
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43       -N or --number N
44           Create N buckets.  The default is 10 buckets.
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46       -g or --graphical
47           Generate a graphical histogram (with asterisks).  Default is
48           numeric.
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50       -I or --last-inclusive
51           Make the last bucket non-inclusive of the last value.
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53       -a  Compute stats over all records (treat non-numeric records as zero
54           rather than just ignoring them).  Default is non-numeric records
55           are ignored.
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57       -e EmptyValue or --empty
58           Specify the value any null bins get.  (Default: -.)
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60       This module also supports the standard fsdb options:
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62       -d  Enable debugging output.
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64       -i or --input InputSource
65           Read from InputSource, typically a file name, or "-" for standard
66           input, or (if in Perl) a IO::Handle, Fsdb::IO or Fsdb::BoundedQueue
67           objects.
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69       -o or --output OutputDestination
70           Write to OutputDestination, typically a file name, or "-" for
71           standard output, or (if in Perl) a IO::Handle, Fsdb::IO or
72           Fsdb::BoundedQueue objects.
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74       --autorun or --noautorun
75           By default, programs process automatically, but Fsdb::Filter
76           objects in Perl do not run until you invoke the run() method.  The
77           "--(no)autorun" option controls that behavior within Perl.
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79       --help
80           Show help.
81
82       --man
83           Show full manual.
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SAMPLE USAGE

86   Input:
87           #fsdb name id test1
88           a 1 80
89           b 2 70
90           c 3 65
91           d 4 90
92           e 5 70
93           f 6 90
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95   Command:
96           cat DATA/grades.fsdb | dbcolhisto -S 0 -E 100 -N 10 test1
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98   Output:
99           #fsdb low histogram:q
100           0       0
101           10      0
102           20      0
103           30      0
104           40      0
105           50      0
106           60      1
107           70      2
108           80      1
109           90      2
110           #  | dbcolhisto -S 0 -E 100 -N 10 test1
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SEE ALSO

113       Fsdb, dbcolpercentile, dbcolstats
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BUGS

116       This program could run in constant memory with no external storage when
117       the buckets are pre-specified.  That optimization is not implemented.
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120       Copyright (C) 1991-2022 by John Heidemann <johnh@isi.edu>
121
122       This program is distributed under terms of the GNU general public
123       license, version 2.  See the file COPYING with the distribution for
124       details.
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128perl v5.38.0                      2023-07-20                     DBCOLHISTO(1)
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