pert/pert

#!/bin/bash
set -o nounset
set -o errexit

function _echo 
{
    echo -e "$1"
}

function _echoB
{
    _echo "\033[1m$1\033[0m"
}

function _help
{
    _echo ""
    _echoB "A command line PERT calculator for quick estimates."
    _echo "Comma separated task list in the form \"1,2,12 4,5,9 2,3,6\", where whitespace separates tasks."
    _echo ""
    _echoB "Usage:"
    _echo "\tpert [optimistic,realistic,pessimistic]"
    _echo ""
    _echoB "Example:"
    _echo "\tpert 1,3,4"
    _echo "\tpert 10,15,20 5,7,10"
    _echo "\tpert \"1,2,3\" \"15,17,20\""
    _echo ""
}

scale=2
function _calc 
{
    _echo "scale=$scale; $@" | bc -l | sed 's/^\./0./'
}

width=88
function _divider
{
    divider=------------------------------
    divider=" +"$divider$divider$divider"+"
    printf "%$width.${width}s+\n" "$divider"
}

readonly format=" | %-12s |%11s |%10s |%12s |%9s |%9s |%9s |\n"
function _header
{
    _echo ""
    _echoB "Tasks"
    _echo ""
    _divider
    printf "$format" "#" "optimistic" "realistic" "pessimistic" "duration" "risk" "variance"
    _divider
}

function pert_table
{
    _header
    
    counter=0
    total_estimate=0
    total_standard_deviation=0
    total_variance=0
    for var in "$@"; do
        
        # counter iterator
        counter=$[$counter +1]
    
        # split values
        IFS=',' read -ra ADDR <<< "$var"
        
        # optimistic value
        o="0"
        if [ -n "${ADDR[0]-}" ]; then
            o=${ADDR[0]}
        fi
        
        # realistic value
        r="0"
        if [ -n "${ADDR[1]-}" ]; then
            r=${ADDR[1]}
        fi
        
        # pessimistic value
        p="0"
        if [ -n "${ADDR[2]-}" ]; then
            p=${ADDR[2]}
        fi
        
        # check values
        if [ -z "$o" ] || [ -z "$r" ] || [ -z "$p" ]; then
            printf "$format" "$counter. bad input" $o $r $p
        else
        
            # pert estimate
            pert_estimate=$(_calc "($o+4*$r+$p)/6")
            total_estimate=$(_calc "$total_estimate + $pert_estimate") 
            
            # standard deviation
            standard_deviation=$(_calc "($p-$o)/6")
            total_standard_deviation=$(_calc "$total_standard_deviation + $standard_deviation")
    
            # variance
            variance=$(_calc "$standard_deviation * $standard_deviation")
            total_variance=$(_calc "$total_variance + $variance")
        
            # row        
            printf "$format" "$counter. task" $o $r $p $pert_estimate $standard_deviation $variance
        fi
    
    done
    
    _divider
    
    if [[ $total_estimate > 0 ]]; then
        
        # footer summary       
        printf "$format" "summary" "-" "-" "-" $total_estimate $total_standard_deviation $total_variance
        _divider
        
        _echo ""
        _echoB "Three point estimates"
        _echo ""
        
        width=42 
        tpeformat=" | %-13s |%11s |%10s |\n"
        
        _divider
        printf "$tpeformat" "confidence"
        _divider
        printf "$tpeformat" "1 Sigma - 68%" $(_calc "$total_estimate - $total_standard_deviation") $(_calc "$total_estimate + $total_standard_deviation")
        printf "$tpeformat" "2 Sigma - 95%" $(_calc "$total_estimate - 2 * $total_standard_deviation") $(_calc "$total_estimate + 2 * $total_standard_deviation")
        printf "$tpeformat" "3 Sigma - 99%" $(_calc "$total_estimate - 3 * $total_standard_deviation") $(_calc "$total_estimate + 3 * $total_standard_deviation")
        _divider
    
    fi
    
    _echo ""
}


# main
if [ $# -eq 0 ]; then
    _help
    exit 1
fi

case "$1" in
  *help|*h)
    _help
    exit 1
    ;;
  *)
    pert_table $@
    exit 0
    ;;
esac