unitproc/bkshuf

   1 #!/usr/bin/env bash
   2 # Desc: Mixes input lines while also preserving some neighbors
   3 # Usage: cat file | bkshuf arg1
   4 # Version 0.1.2
   5 # Depends: bc 1.07.1, GNU Coreutils 8.32 (shuf)
   6 # Input: var: arg1  initial lines to output
   7
   8 # Load env vars
   9 ## For these numbers of lines of input...
  10 if [[ ! -v BKSHUF_PARAM_LINEC ]]; then BKSHUF_PARAM_LINEC=1000000; fi;
  11 ##   ... target this group size.
  12 if [[ ! -v BKSHUF_PARAM_GSIZE ]]; then BKSHUF_PARAM_GSIZE=25; fi;
  13
  14
  15 yell() { echo "$0: $*" >&2; } # print script path and all args to stderr
  16 die() { yell "$*"; exit 111; } # same as yell() but non-zero exit status
  17 must() { "$@" || die "cannot $*"; } # runs args as command, reports args if command fails
  18 read_stdin() {
  19     # Desc: Consumes stdin; outputs as stdout lines
  20     # Input: stdin (consumes)
  21     # Output: stdout (newline delimited)
  22     # Example: printf "foo\nbar\n" | read_stdin
  23     # Depends: GNU bash (version 5.1.16)
  24     # Version: 0.0.1
  25     local input_stdin output;
  26
  27     # Store stdin
  28     if [[ -p /dev/stdin ]]; then
  29         input_stdin="$(cat -)";
  30     fi;
  31
  32     # Store as output array elements
  33     ## Read in stdin
  34     if [[ -n $input_stdin ]]; then
  35         while read -r line; do
  36             output+=("$line");
  37         done < <(printf "%s\n" "$input_stdin");
  38     fi;
  39
  40     # Print to stdout
  41     printf "%s\n" "${output[@]}";
  42 }; # read stdin to stdout lines
  43 checkInt() {
  44     # Desc: Checks if arg is integer
  45     # Usage: checkInt arg
  46     # Input: arg: integer
  47     # Output: - return code 0 (if arg is integer)
  48     #         - return code 1 (if arg is not integer)
  49     # Example: if ! checkInt $arg; then echo "not int"; fi;
  50     # Version: 0.0.1
  51     local returnState
  52
  53     #===Process Arg===
  54     if [[ $# -ne 1 ]]; then
  55         die "ERROR:Invalid number of arguments:$#";
  56     fi;
  57
  58     RETEST1='^[0-9]+$'; # Regular Expression to test
  59     if [[ ! $1 =~ $RETEST1 ]] ; then
  60         returnState="false";
  61     else
  62         returnState="true";
  63     fi;
  64
  65     #===Determine function return code===
  66     if [ "$returnState" = "true" ]; then
  67         return 0;
  68     else
  69         return 1;
  70     fi;
  71 } # Checks if arg is integer
  72 consume_line() {
  73     # Desc: Outputs and destroys line from list_input starting at index ip
  74     # Usage: consume_line;
  75     # Input: var: list_input  array input lines
  76     #        var: lco         int   line count original
  77     #        var: lcr         int   line count remaining
  78     #        var: ip          int   list_input index pointer
  79     # Output: stdout:    a single non-blank element from list_input
  80     #         list_input     one element destroyed
  81     #         var: lc_out    incremented once
  82     local n line;
  83
  84     n=0; # for tracking progress iterating through remaining list_input
  85     ### Loop once through list_input indices until a non-blank line found
  86     while [[ $n -le $lco ]]; do
  87         #### check if line at ip is blank
  88         line="${list_input[$ip]}";
  89         if [[ -n $line ]]; then
  90             ##### consume line at index ip
  91             printf "%s\n" "$line" & # print to output
  92             unset "list_input[$ip]"; # destroy line in list_input array
  93             ((lc_out++));
  94             ((lcr--)); # decrement line count remaining lcr
  95             #yell "DEBUG:Consumed line ip:$ip:$line";
  96             break;
  97         fi;
  98         #### increment input index pointer, looping around if necessary
  99         if [[ $ip -le $lco ]]; then ((ip++)); else ip=0; fi;
 100         #### track progress through list_input
 101         ((n++));
 102     done;
 103 }; # consume and output line in list_input array starting at index ip
 104 decide_read() {
 105     # Desc: Decides whether to read another line in list_input array
 106     #   by comparing $RANDOM to p_seq_int
 107     # Usage:  if decide_read; then something; fi;
 108     # Input: var: p_seq_int probability (int [0 32767])
 109
 110     if [[ $RANDOM -lt $p_seq_int ]]; then
 111         return 0;
 112     else
 113         return 1;
 114     fi;
 115 }; # returns 0 with probability p_seq; 1 otherwise
 116
 117 main() {
 118     declare par_l0 par_s0 s_exp s;
 119     declare -a list_input;
 120
 121     # Check positional arguments
 122     if [[ $# -gt 0 ]] && ! checkInt "$1"; then
 123         die "FATAL:Not an integer:$1";
 124     else
 125         lc_out_max="$1"; # output line count
 126     fi;
 127
 128     # Check env vars
 129     if ! checkInt "$BKSHUF_PARAM_LINEC"; then
 130         die "FATAL:Not an int:BKSHUF_PARAM_LINEC:$BKSHUF_PARAM_LINEC"; fi;
 131     if ! checkInt "$BKSHUF_PARAM_GSIZE"; then
 132         die "FATAL:Not an int:BKSHUF_PARAM_LINEC:$BKSHUF_PARAM_GSIZE"; fi;
 133
 134     # store input lines from stdin (like `shuf`)
 135     while read -r line; do
 136         if [[ -z $line ]]; then continue; fi; # skip blank lines
 137         #yell "DEBUG:INPUT:$line";
 138         list_input+=("$line");
 139     done < <( read_stdin; );
 140
 141     # calc line count (lc)
 142     lc="${#list_input[@]}";
 143     #lc="$(printf "%s\n" "${list_input[@]}" | wc -l )";
 144     #yell "DEBUG:lc:$lc";
 145     #yell "DEBUG:list_input:$(declare -p list_input)";
 146
 147     # calculate group size s
 148     par_l0="$BKSHUF_PARAM_LINEC";
 149     par_s0="$BKSHUF_PARAM_GSIZE";
 150     s_exp="(( $par_s0 - 1 )/( ( l( $par_l0 ) )^2 ))*(l( $lc ))^2+1";
 151     s="$(echo "scale=12; $s_exp" | bc -l)";
 152
 153     # calculate probabilities p_jump, p_seq
 154     p_jump="$(echo "scale=12; 1 / ( $s )" | bc -l)";
 155     p_seq="$(echo "scale=12; 1 - $p_jump" | bc -l)";
 156     p_seq_int="$(echo "scale=0; ($p_seq * 32767)/1" | bc -l)"; # p_seq as int [0 32767] for $RANDOM range
 157
 158     # generate output
 159     lco="${#list_input[@]}"; # save original input line count
 160     lcr="$lco";
 161     lc_out="0"; # init output line counter
 162     if [[ -z "$lc_out_max" ]]; then lc_out_max="$lco"; fi;
 163     ip="$(shuf -i0-$(( lco - 1 )) -n1)"; # init input index pointer
 164     RANDOM="$(shuf -i0-32767 -n1)"; # init Bash PRNG
 165     n_loop1="0";
 166     #yell "DEBUG:max_blanks:$max_blanks"
 167     while [[ $lcr -ge 1 ]] && [[ $lc_out -lt $lc_out_max ]]; do
 168         ## Select random unconsumed input line and consume it to output
 169         ip="$(shuf -i0-$(( lco - 1 )) -n1)"; # init input index pointer
 170         consume_line;
 171
 172         ## Consume the next sequential line with probability p_seq.
 173         while decide_read && [[ $lcr -ge 1 ]] && [[ $lc_out -lt $lc_out_max ]]; do
 174             consume_line;
 175         done;
 176
 177         ((n_loop1++)); # increment jump counter
 178     done;
 179     #yell "DEBUG:n_loop1:$n_loop1"; # count jumps
 180
 181 }; # main program
 182
 183 main "$@";
 184
 185 # Author: Steven Baltakatei Sandoval
 186 # License: GPLv3+
 187
 188 # Dependency information
 189
 190 # bc 1.07.1
 191 # Copyright 1991-1994, 1997, 1998, 2000, 2004, 2006, 2008, 2012-2017 Free Software Foundation, Inc.
 192
 193
 194 # shuf (GNU coreutils) 8.32
 195 # Copyright (C) 2020 Free Software Foundation, Inc.
 196 # License GPLv3+: GNU GPL version 3 or later <https://gnu.org/licenses/gpl.html>.
 197 # This is free software: you are free to change and redistribute it.
 198 # There is NO WARRANTY, to the extent permitted by law.
 199
 200 # Written by Paul Eggert.
 201
 202