Hierarchical Sorting

For this challenge, you must create a sort function that will sort a dataset in a hierarchical manner. Use your function to sort the data-big-input.txt file by net_sales_units, from highest to lowest.

Dataset Format

The raw datasets are pipe-delimited CSV files / strings. We've attached some examples at the bottom of this gist.

The dataset's columns are:

Properties: property0, property1, ..., propertyN
Metrics: any non-property column

Example

Here's an example dataset input with 2 properties, and one metric (net_sales).

property0	property1	net_sales
bar	$total	-200
foo	sauce	300
$total	$total	200
bar	sup	-400
foo	$total	400
bar	bro	200
foo	lettuce	100

The sort function should produce an output that's sorted like this:

property0	property1	net_sales
$total	$total	200
foo	$total	400
foo	sauce	300
foo	lettuce	100
bar	$total	-200
bar	bro	200
bar	sup	-400

Explanation

Let's reformat the data, to visualize its hierarchy:

/$total/$total

/foo/$total
/foo/sauce
/foo/lettuce

/bar/$total
/bar/bro
/bar/sup

The general idea is:

/.../$total/$total
/.../propertyN-1/$total
/.../propertyN-1/propertyN

If a property's value is $total, it means that the row represents the total for its level.

The total rows rank higher than all other rows in the level, regardless of the sorting criteria. In our example, the /bar/$total is not the highest value in the /bar group, but it's still at the top.

The non-$total values are sorted against all other values within a parent's grouping.

Instructions

What to submit

A gist or zip/tarball containing:
- A program that can read an input dataset, and produce a hierarchically sorted output
- An output file created by your program:
  - Using data-big-input.txt as the input dataset
  - Sorted on the net_sales_units metric, from highest to lowest.

Protips

The level's $total row should always be at the top of the level, even if it's not the highest value. See examples below.
The output dataset should be formatted like the input (i.e. pipe-delimited CSV with header).
We use TypeScript and Python, but you can use any language (and include instructions on how to run your code).
If using Python, avoid using pandas or notebooks. Use minimal external libraries.
You are allowed to use a built-in sort function as long as it is only used to sort a list.
Try to validate your solution by running it against the example datasets (see below).

Don't hardcode the number of property / metric columns

Ideally, your code should not assume anything about the number of property or metric columns in the input. In our application, the input could have 10 property and 100 metrics.

The input always follows the same pattern:

For properties, the keys are: propertyN
The other keys are metrics.

Don't hardcode the sort metric

Ideally, the algorithm should allow the user to specify which metric to sort on (instead of hardcoding to net_sales_units).

The function signature could look something like this:

function hierarchicalSort(rows, getSortValueFn) {
    // your code goes here
}

// calling it
hierarchicalSort(rows, row => row.net_sales);

In our application, we go a step further and allow the user to define the sort metric per property.

andredias/42technologies_technical_challenge