data mapping

map-sort.sh

#!/usr/bin/env bash

input_file="$1"

declare -A data
declare -A items
declare -A dates

# Read the data and populate arrays
while IFS=$'\t' read -r date item count; do
    if [ "$date" != "date" ]; then
        items["$item"]=1
        dates["$date"]=1
        data["$date,$item"]=$count
    fi
done < "$input_file"

# Sort the item keys
sorted_items=($(printf "%s\n" "${!items[@]}" | sort))

# Prepare the header
{
    echo -n "date"
    for item in "${sorted_items[@]}"; do
        echo -ne "\t$item"
    done
    echo
}

# Generate the output
for date in "${!dates[@]}"; do
    echo -n "$date"
    for item in "${sorted_items[@]}"; do
        echo -ne "\t${data["$date,$item"]:-0}"
    done
    echo
done