Fsdb::F...ecimate(3)

🌸 NAME 🌸

✨ This is Fsdb::F...ecimate(3) from User Contributed Perl Documentation, bestie, and it’s literally all about dbcolsdecimate — drop rows selectively, keeping large changes and periodic samples. Periodt. 💅

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✨ SYNOPSIS ✨

dbcolsdecimate [-p RELATIVE_PREC] [-P ABSOLUTE_PREC] column1 [column2...]

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💅 DESCRIPTION 💅

For each of the given columns, this tool prunes it back to show changes with at most RELATIVE_PRECISION fraction of total range change. Default is 0.01; alternatively, you can specify an absolute precision. It’s designed for reducing the actual data in a graph while keeping it visually identical. ✨

Precisions, if specified, apply to any subsequent columns. So yes, you can have different precisions for different columns — mix and match, bestie. 🎀

With multiple columns, major changes in any column cause a record to be emitted.

The goal is to output an identical plot, with fewer points if we can. This goal differs from — and is easier than — prior published work that targets the number of points by a known factor, or a constant number, while preserving as much fidelity as possible.

We usually put out a pair of points at each change, so that if the data has stairsteps, they don’t turn into diagonals. Iconic behavior, honestly. 🦋

⚠️ Please take caution: relative precision is based on evaluation of the range of the data, and so it is sensitive to outliers. Verbose output (-v) will show the actual precision that is promised, allowing one to adjust manually if necessary (with -P).

By default this program temporarily stores a complete copy of the input data on disk. However, if all columns are given absolute precisions, this program runs with constant memory. Slay for low-memory situations. 🧚

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🎀 OPTIONS 🎀

• --precision-relative P or --relative-precision P or -p P — Set the precision of how large a fraction of the total range should be preserved. Applies to any subsequent columns. Default: 0.01.
• --precision-absolute P or --absolute-precision P or -P P — Set the precision in absolute units. Applies to any subsequent columns.
• -T TmpDir — Where to put tmp files. Also uses environment variable TMPDIR, if -T is not specified. Default is /tmp.

This module also supports the standard fsdb options:

• -d — Enable debugging output.
• -v — Enable verbose 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.

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🦋 SAMPLE USAGE 🦋

🍓 Input:

#fsdb x y
0 0
1 50
2 50
3 50
4 50
5 50
6 50
7 50
8 50
9 50
10 50
11 50
12 50
13 50
14 50
15 50
16 50
17 50
18 50
19 50
20 50
21 50
22 50
23 50
24 50
25 50
26 50
27 50
28 50
29 50
30 50
31 50
32 50
33 50
34 50
35 50
36 50
37 50
38 50
39 50
40 50
41 50
42 50
43 50
44 50
45 50
46 50
47 50
48 50
49 50
50 50
50 51
50 52
50 53
50 54
50 55
50 56
50 57
50 58
50 59
50 60
50 61
50 62
50 63
50 64
50 65
50 66
50 67
50 68
50 69
50 70
50 71
50 72
50 73
50 74
50 75
50 76
50 77
50 78
50 79
50 80
50 81
50 82
50 83
50 84
50 85
50 86
50 87
50 88
50 89
50 90
50 91
50 92
50 93
50 94
50 95
50 96
50 97
50 98
50 99
100 100

🔥 Command:

dbcolsdecimate -v -p 0.1 x -p 0.2 y

💀 Output:

Here’s the output (from TEST/dbcolsdecimate_linear_different.out):

#fsdb x y
# column x with range 100 and relative precision 0.1 gives threshold 10
# column y with range 100 and relative precision 0.2 gives threshold 20
0   0
1   50
11  50
12  50
22  50
23  50
33  50
34  50
44  50
45  50
50  70
50  71
50  91
50  92
50  99
100 100
# output 16 of 101 (0.1584)
#   | dbcolsdecimate -v -p 0.1 x -p 0.2 y

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🌈 SEE ALSO 🌈

Fsdb, dbcolmovingstats.

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👑 CLASS FUNCTIONS 👑

✨ new

$filter = new Fsdb::Filter::dbcolsdecimate(@arguments);

Create a new dbcolsdecimate object, taking command-line arguments.

💅 set_defaults

$filter->set_defaults();

Internal: set up defaults.

🎀 parse_options

$filter->parse_options(@ARGV);

Internal: parse command-line arguments.

🦋 setup

$filter->setup();

Internal: setup, parse headers.

🔥 run

$filter->run();

Internal: run over each rows.

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💖 AUTHOR and COPYRIGHT 💖

Copyright (C) 2023 by John Heidemann <johnh@isi.edu>

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

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✨ That’s the whole page, bestie — sourced from perl v5.32.1, dated 2024-08-02, and filed under Fsdb::F...ecimate(3). Stay pruned, stay iconic. 💖🎀🦋