wltp 0.1.2a0

wltp: generate WLTC gear-shifts based on vehicle characteristics

release:

0.1.2a0

date:

2019-06-05 22:10:33

documentation:

https://wltp.readthedocs.org/ (build-date: x.x.x)

source:

https://github.com/JRCSTU/wltp

pypi-repo:

https://pypi.python.org/pypi/wltp

keywords:

UNECE, automotive, car, cars, driving, engine, fuel-consumption, gears, gearshifts, rpm, simulation, simulator, standard, vehicle, vehicles, wltc, nedc

Copyright:

2013-2014 European Commission (JRC-IET)

License:

EUPL 1.1+

A python package to generate the gear-shifts of Light-duty vehicles running the WLTP driving-cycles, according to UNECE’s GTRs.

Attention!

This wltp python project is still in alpha stage, in the send that its results are not “correct” by the standard, and no WLTP dyno-tests should rely currently on them.

Some of the known deficiencies are described in these places:

• In the doc(CHANGES).

• Presented in the diagrams of the doc(metrics) section.

• Imprinted in the mod(~wltp.test.wltp_db_tests) test-case which automatically compares, on each build, the mean RPMs & Gears of this program against Heinz’s phase-1a (end of 2014) MSAccess, for a pre-determined set of Heinz-db vehicles. Currently, genrated mean-RPMs differ from Heinz-db < 0.5% and gears < 5% for a 1800-step class-3 cycle.

Table of Contents

• Introduction

  • Overview

  • Quick-start

• Install

  • Python installation

  • Package installation

  • Older versions

  • Installing from sources

  • Project files and folders

• Usage

  • Cmd-line usage

  • Excel usage

  • Python usage

  • IPython notebook usage

    • Requirements

    • Instructions

• Getting Involved

  • Sources & Dependencies

  • Development procedure

  • Specs & Algorithm

    • Cycles

  • Development team

• Glossary

Introduction

Overview

The calculator accepts as input the vehicle’s technical data, along with parameters for modifying the execution of the WLTC cycle, and it then spits-out the gear-shifts of the vehicle, the attained speed-profile, and any warnings. It does not calculate any COsub(2) emissions.

An “execution” or a “run” of an experiment is depicted in the following diagram:

           .---------------------.                         .----------------------------.
          ;   Input-DataModel   ;                         ;      Output-DataModel       ;
         ;---------------------;                         ;----------------------------;
        ; +--vehicle          ;     ____________        ; +---...                    ;
       ;  +--params          ;     |            |      ;  +--cycle_run:             ;
      ;       +--wltc_data  ;  ==> |   Cycle    | ==> ;      t  v_class gear ...   ;
     ;                     ;       | Generator  |    ;      --------------------  ;
    ;                     ;        |____________|   ;       00      0.0    1     ;
   ;                     ;                         ;        01      1.3    1    ;
  ;                     ;                         ;         02      5.5    1   ;
 ;                     ;                         ;          ...               ;
'---------------------'                         '----------------------------.

The Input & Output DataModels are instances of pandas-model, trees of strings and numbers, assembled with:

• sequences,

• dictionaries,

• class(pandas.DataFrame),

• class(pandas.Series), and

• URI-references to other model-trees.

Quick-start

Note

The program runs on Python-2.7+ and Python-3.3+ (preferred) and requires numpy/scipy, pandas and win32 libraries along with their native backends to be installed. If you do not have such an environment already installed, please read doc(install) section below for suitable distributions such as WinPython or Anaconda.

Assuming that you have a working python-environment, open a command-shell, (in Windows use program(cmd.exe) BUT ensure program(python.exe) is in its env[$PATH]), you can try the following commands:

Tip

The commands beginning with $, below, imply a Unix like operating system with a POSIX shell (Linux, OS X). Although the commands are simple and easy to translate in its Windows cmd.exe counterpart, it would be worthwile to install Cygwin to get the same environment on Windows. If you choose to do that, include also the following packages in the Cygwin’s installation wizard:

* git, git-completion
* make, zip, unzip, bzip2, dos2unix
* openssh, curl, wget

But do not install/rely on cygwin’s outdated python environment.

Install:

$ pip install wltp                      ## Use `--pre` if version-string has a build-suffix.
$ wltp --winmenus                       ## Adds StartMenu-items, Windows only.

Or in case you need the very latest from master branch :

$ pip install git+git://github.com/ankostis/wltp.git@master --pre

See: doc(install)

Cmd-line:

$ wltp --version
0.1.2a0

$ wltp --help
...

See: ref: cmd-line-usage

Excel:

$ wltp --excelrun                       ## Windows & OS X only

See: ref: excel-usage

Python-code:

from wltp.experiment import Experiment

input_model = { ... }           ## See also "Python Usage" for model contents.
exp = Experiment(input_model)
output_model = exp.run()
print('Results: \n%s' % output_model['cycle_run'])

See: ref: python-usage

Install

Current version(x.x.x) runs on Python-2.7+ and Python-3.3+ and requires numpy/scipy, pandas and win32 libraries along with their native backends to be installed.

It has been tested under Windows and Linux and Python-3.3+ is the preferred interpreter, i.e, the Excel interface and desktop-UI runs only with it.

It is distributed on Wheels.

Python installation

Warning

On Windows it is strongly suggested NOT to install the standard CPython distribution, unless:

1. you have administrative priviledges,

2. you are an experienced python programmer, so that

3. you know how to hunt dependencies from PyPi repository and/or the Unofficial Windows Binaries for Python Extension Packages.

As explained above, this project depends on packages with native-backends that require the use of C and Fortran compilers to build from sources. To avoid this hassle, you should choose one of the user-friendly distributions suggested below.

Below is a matrix of the two suggested self-wrapped python distributions for running this program (we excluded here default python included in linux). Both distributions:

• are free (as of freedom),

• do not require admin-rights for installation in Windows, and

• have been tested to run successfully this program (also tested on default linux distros).

Distributions	WinPython	Anaconda
Platform	Windows	Windows, Mac OS, Linux
Ease of Installation	Fair Currently (March-2015) it requires fiddling with the env[$PATH] after install.	Anaconda: Easy MiniConda: Moderate
Ease of Use	Easy	Moderate Should use command(conda) and/or command(pip) depending on whether a package contains native libraries
# of Packages	Only what’s included in the downloaded-archive	Many 3rd-party packages uploaded by users
Notes	After installation, see faq for: Registering WinPython installation Adding your installation in env[$PATH]	Check also the lighter miniconda. For installing native-dependencies with command(conda) see files: - file(requirements/miniconda.txt) - file(.travis.yaml)
	Check also installation instructions from the pandas site.

Package installation

Before installing it, make sure that there are no older versions left over on the python installation you are using. To cleanly uninstall it, run this command until you cannot find any project installed:

$ pip uninstall wltp                        ## Use `pip3` if both python-2 & 3 are in PATH.

You can install the project directly from the PyPi repo the “standard” way, by typing the command(pip) in the console:

$ pip install wltp

• If you want to install a pre-release version (the version-string is not plain numbers, but ends with alpha, beta.2 or something else), use additionally option(–pre).

$ pip install wltp

• Also you can install the very latest version straight from the sources:

  $ pip install git+git://github.com/ankostis/wltp.git  --pre

• If you want to upgrade an existing instalation along with all its dependencies, add also option(–upgrade) (or option(-U) equivalently), but then the build might take some considerable time to finish. Also there is the possibility the upgraded libraries might break existing programs(!) so use it with caution, or from within a virtualenv (isolated Python environment).

• To install it for different Python environments, repeat the procedure using the appropriate program(python.exe) interpreter for each environment.

• Tip

  To debug installation problems, you can export a non-empty env[$DISTUTILS_DEBUG] and distutils will print detailed information about what it is doing and/or print the whole command line when an external program (like a C compiler) fails.

After installation, it is important that you check which version is visible in your env[$PATH]:

$ wltp --version
0.1.2a0

To install for different Python versions, repeat the procedure for every required version.

Older versions

An additional purpose of the versioning schema of the project is to track which specific version of the GTR it implements. Given a version number MAJOR.MINOR.PATCH, the MAJOR part tracks the GTR phase implemented. See the “GTR version matrix” section in doc(CHANGES) for the mapping of MAJOR-numbers to GTR versions.

To install an older released version issue the console command:

$ pip install wltp=1.1.1                    ## Use `--pre` if version-string has a build-suffix.

or alternatively straight from the sources:

$ pip install git+git://github.com/ankostis/wltp.git@v0.0.9-alpha.3.1  --pre

Ofcourse you can substitute v0.0.9-alpha.3.1 with any slug from “commits”, “branches” or “releases” that you will find on project’s github-repo).

Note

If you have another version already installed, you have to use option(–ignore-installed) (or option(-I)). For using the specific version, check this (untested) stackoverflow question .

You can install each version in a separate virtualenv (isolated Python environment) and shy away from all this. Check

Installing from sources

If you download the sources you have more options for installation. There are various methods to get hold of them:

• Download the source distribution from PyPi repo.

• Download a release-snapshot from github

• Clone the git-repository at github.

  Assuming you have a working installation of git you can fetch and install the latest version of the project with the following series of commands:

  $ git clone "https://github.com/JRCSTU/wltp.git" wltp.git
  $ cd wltp.git
  $ python setup.py install                                 ## Use `python3` if both python-2 & 3 installed.

When working with sources, you need to have installed all libraries that the project depends on:

$ pip install -r requirements/execution.txt .

The previous command installs a “snapshot” of the project as it is found in the sources. If you wish to link the project’s sources with your python environment, install the project in development mode:

$ python setup.py develop

Note

This last command installs any missing dependencies inside the project-folder.

Project files and folders

The files and folders of the project are listed below:

+--wltp/            ## (package) The python-code of the calculator
|   +--cycles/      ## (package) The python-code for the WLTC data
|   +--test/        ## (package) Test-cases and the wltp_db
|   +--model        ## (module) Describes the data and their schema for the calculation
|   +--experiment   ## (module) The calculator
|   +--plots        ## (module) Diagram-plotting code and utilities
+--docs/            ## Documentation folder
|   +--pyplots/     ## (scripts) Plot the metric diagrams embeded in the README
+--devtools/        ## (scripts) Preprocessing of WLTC data on GTR and the wltp_db
|   +--run_tests.sh ## (script) Executes all TestCases
+--setup.py         ## (script) The entry point for `setuptools`, installing, testing, etc
+--requirements/    ## (txt-files) Various pip-dependencies for tools.
+--README.rst
+--CHANGES.rst
+--LICENSE.txt

Usage

Cmd-line usage

Warning

Not implemented in yet.

The command-line usage below requires the Python environment to be installed, and provides for executing an experiment directly from the OS’s shell (i.e. program(cmd) in windows or program(bash) in POSIX), and in a single command. To have precise control over the inputs and outputs (i.e. experiments in a “batch” and/or in a design of experiments) you have to run the experiments using the API python, as explained below.

The entry-point script is called program(wltp), and it must have been placed in your env[$PATH] during installation. This script can construct a model by reading input-data from multiple files and/or overriding specific single-value items. Conversely, it can output multiple parts of the resulting-model into files.

To get help for this script, use the following commands:

$ wltp --help                               ## to get generic help for cmd-line syntax
$ wltcmdp.py -M vehicle/full_load_curve     ## to get help for specific model-paths

and then, assuming vehicle.csv is a CSV file with the vehicle parameters for which you want to override the n_idle only, run the following:

$ wltp -v \
    -I vehicle.csv file_frmt=SERIES model_path=params header@=None \
    -m vehicle/n_idle:=850 \
    -O cycle.csv model_path=cycle_run

Excel usage

Attention!

Excel-integration requires Python 3 and Windows or OS X!

In Windows and OS X you may utilize the excellent xlwings library to use Excel files for providing input and output to the experiment.

To create the necessary template-files in your current-directory you should enter:

$ wltp --excel

You could type instead samp(wltp –excel {file_path}) to specify a different destination path.

In windows/OS X you can type samp(wltp –excelrun) and the files will be created in your home-directory and the excel will open them in one-shot.

All the above commands creates two files:

file(wltp_excel_runner.xlsm)

The python-enabled excel-file where input and output data are written, as seen in the screenshot below:

After opening it the first tie, enable the macros on the workbook, select the python-code at the left and click the menuselection(Run Selection as Pyhon) button; one sheet per vehicle should be created.

The excel-file contains additionally appropriate VBA modules allowing you to invoke Python code present in selected cells with a click of a button, and python-functions declared in the python-script, below, using the mypy namespace.

To add more input-columns, you need to set as column Headers the json-pointers path of the desired model item (see ref: python-usage below,).

file(wltp_excel_runner.py)

Utility python functions used by the above xls-file for running a batch of experiments.

The particular functions included reads multiple vehicles from the input table with various vehicle characteristics and/or experiment parameters, and then it adds a new worksheet containing the cycle-run of each vehicle . Of course you can edit it to further fit your needs.

Note

You may reverse the procedure described above and run the python-script instead. The script will open the excel-file, run the experiments and add the new sheets, but in case any errors occur, this time you can debug them, if you had executed the script through LiClipse, or IPython!

Some general notes regarding the python-code from excel-cells:

• On each invocation, the predefined VBA module pandalon executes a dynamically generated python-script file in the same folder where the excel-file resides, which, among others, imports the “sister” python-script file. You can read & modify the sister python-script to import libraries such as ‘numpy’ and ‘pandas’, or pre-define utility python functions.

• The name of the sister python-script is automatically calculated from the name of the Excel-file, and it must be valid as a python module-name. Therefore do not use non-alphanumeric characters such as spaces(`` ), dashes(-) and dots(.``) on the Excel-file.

• On errors, a log-file is written in the same folder where the excel-file resides, for as long as the message-box is visible, and it is deleted automatically after you click ‘ok’!

• Read http://docs.xlwings.org/quickstart.html

Python usage

Example python REPL (Read-Eval-Print Loop) example-commands are given below that setup and run an experiment.

First run command(python) or command(ipython) and try to import the project to check its version:

code-block:

>>> import wltp

>>> wltp.__version__            ## Check version once more.
'0.1.2a0'

>>> wltp.__file__               ## To check where it was installed.         # doctest: +SKIP
/usr/local/lib/site-package/wltp-...

If everything works, create the pandas-model that will hold the input-data (strings and numbers) of the experiment. You can assemble the model-tree by the use of:

• sequences,

• dictionaries,

• class(pandas.DataFrame),

• class(pandas.Series), and

• URI-references to other model-trees.

For instance:

code-block:

>>> from wltp import model
>>> from wltp.experiment import Experiment
>>> from collections import OrderedDict as odic         ## It is handy to preserve keys-order.

>>> mdl = odic(
...   vehicle = odic(
...     unladen_mass = 1430,
...     test_mass    = 1500,
...     v_max        = 195,
...     p_rated      = 100,
...     n_rated      = 5450,
...     n_idle       = 950,
...     n_min        = None,                            ## Manufacturers my overridde it
...     gear_ratios         = [120.5, 75, 50, 43, 37, 32],
...     resistance_coeffs   = [100, 0.5, 0.04],
...   )
... )

For information on the accepted model-data, check its JSON-schema:

code-block:

>>> model.json_dumps(model.model_schema(), indent=2)                                # doctest: +SKIP
{
  "properties": {
    "params": {
      "properties": {
        "f_n_min_gear2": {
          "description": "Gear-2 is invalid when N :< f_n_min_gear2 * n_idle.",
          "type": [
            "number",
            "null"
          ],
          "default": 0.9
        },
        "v_stopped_threshold": {
          "description": "Velocity (Km/h) under which (<=) to idle gear-shift (Annex 2-3.3, p71).",
          "type": [
...

You then have to feed this model-tree to the class(~wltp.experiment.Experiment) constructor. Internally the class(~wltp.pandel.Pandel) resolves URIs, fills-in default values and validates the data based on the project’s pre-defined JSON-schema:

code-block:

>>> processor = Experiment(mdl)         ## Fills-in defaults and Validates model.

Assuming validation passes without errors, you can now inspect the defaulted-model before running the experiment:

code-block:

>>> mdl = processor.model               ## Returns the validated model with filled-in defaults.
>>> sorted(mdl)                         ## The "defaulted" model now includes the `params` branch.
['params', 'vehicle']
>>> 'full_load_curve' in mdl['vehicle'] ## A default wot was also provided in the `vehicle`.
True

Now you can run the experiment:

code-block:

>>> mdl = processor.run()               ## Runs experiment and augments the model with results.
>>> sorted(mdl)                         ## Print the top-branches of the "augmented" model.
['cycle_run', 'params', 'vehicle']

To access the time-based cycle-results it is better to use a class(pandas.DataFrame):

code-block:

>>> import pandas as pd
>>> df = pd.DataFrame(mdl['cycle_run']); df.index.name = 't'
>>> df.shape                            ## ROWS(time-steps) X COLUMNS.
(1801, 11)
>>> df.columns
Index(['v_class', 'v_target', 'clutch', 'gears_orig', 'gears', 'v_real', 'p_available', 'p_required', 'rpm', 'rpm_norm', 'driveability'], dtype='object')
>>> 'Mean engine_speed: %s' % df.rpm.mean()
'Mean engine_speed: 1940.72109939'
>>> df.describe()
           v_class     v_target     clutch   gears_orig        gears  \
count  1801.000000  1801.000000       1801  1801.000000  1801.000000
mean     46.506718    46.506718  0.0660744     3.794003     3.683509
std      36.119280    36.119280  0.2484811     2.278959     2.278108
...
<BLANKLINE>
            v_real  p_available   p_required          rpm     rpm_norm
count  1801.000000  1801.000000  1801.000000  1801.000000  1801.000000
mean     50.356222    28.846639     4.991915  1940.721099     0.214898
std      32.336908    15.833262    12.139823   840.959339     0.195142
...

>>> processor.driveability_report()                                             # doctest: +SKIP
...
  12: (a: X-->0)
  13: g1: Revolutions too low!
  14: g1: Revolutions too low!
...
  30: (b2(2): 5-->4)
...
  38: (c1: 4-->3)
  39: (c1: 4-->3)
  40: Rule e or g missed downshift(40: 4-->3) in acceleration?
...
  42: Rule e or g missed downshift(42: 3-->2) in acceleration?
...

You can export the cycle-run results in a CSV-file with the following pandas command:

>>> df.to_csv('cycle_run.csv')                                                      # doctest: +SKIP

For more examples, download the sources and check the test-cases found under the file(/wltp/test/) folder.

IPython notebook usage

The list of IPython notebooks for wltp is maintained at the wiki of the project.

Requirements

In order to run them interactively, ensure that the following requirements are satisfied:

1. A ipython-notebook server >= v2.x.x is installed for python-3, it is up, and running.

2. The wltp is installed on your system (see doc(install) above).

Instructions

• Visit each notebook from the wiki-list that you wish to run and download it as file(ipynb) file from the menu (menuselection(File|Download as…|IPython Notebook(.ipynb))).

• Locate the downloaded file with your file-browser and drag n’ drop it on the landing page of your notebook’s server (the one with the folder-list).

Enjoy!

Getting Involved

This project is hosted in github. To provide feedback about bugs and errors or questions and requests for enhancements, use github’s Issue-tracker.

Sources & Dependencies

To get involved with development, you need a POSIX environment to fully build it (Linux, OSX or Cygwin on Windows).

First you need to download the latest sources:

$ git clone https://github.com/JRCSTU/wltp.git wltp.git
$ cd wltp.git

Virtualenv

You may choose to work in a virtualenv (isolated Python environment), to install dependency libraries isolated from system’s ones, and/or without admin-rights (this is recommended for Linux/Mac OS).

Attention!

If you decide to reuse stystem-installed packages using option(–system-site-packages) with virtualenv <= 1.11.6 (to avoid, for instance, having to reinstall numpy and pandas that require native-libraries) you may be bitten by bug #461 which prevents you from upgrading any of the pre-installed packages with command(pip).

Liclipse IDE

Within the sources there are two sample files for the comprehensive LiClipse IDE:

• file(eclipse.project)

• file(eclipse.pydevproject)

Remove the eclipse prefix, (but leave the dot(.)) and import it as “existing project” from Eclipse’s File*` menu.

Another issue is caused due to the fact that LiClipse contains its own implementation of Git, EGit, which badly interacts with unix symbolic-links, such as the file(docs/docs), and it detects working-directory changes even after a fresh checkout. To workaround this, Right-click on the above file menuselection(Properties –> Team –> Advanced –> Assume Unchanged)

Then you can install all project’s dependencies in `development mode using the file(setup.py) script:

$ python setup.py --help                           ## Get help for this script.
Common commands: (see '--help-commands' for more)

  setup.py build      will build the package underneath 'build/'
  setup.py install    will install the package

Global options:
  --verbose (-v)      run verbosely (default)
  --quiet (-q)        run quietly (turns verbosity off)
  --dry-run (-n)      don't actually do anything
...

$ python setup.py develop                           ## Also installs dependencies into project's folder.
$ python setup.py build                             ## Check that the project indeed builds ok.

You should now run the test-cases (see doc(metrics)) to check that the sources are in good shape:

$ python setup.py test

Note

The above commands installed the dependencies inside the project folder and for the virtual-environment. That is why all build and testing actions have to go through samp(python setup.py {some_cmd}).

If you are dealing with installation problems and/or you want to permantly install dependant packages, you have to deactivate the virtual-environment and start installing them into your base python environment:

$ deactivate
$ python setup.py develop

or even try the more permanent installation-mode:

$ python setup.py install                # May require admin-rights

Development procedure

For submitting code, use UTF-8 everywhere, unix-eol(LF) and set git --config core.autocrlf = input.

The typical development procedure is like this:

1. Modify the sources in small, isolated and well-defined changes, i.e. adding a single feature, or fixing a specific bug.

2. Add test-cases “proving” your code.

3. Rerun all test-cases to ensure that you didn’t break anything, and check their coverage remain above 80%:

   $ python setup.py nosetests --with-coverage --cover-package wltp.model,wltp.experiment --cover-min-percentage=80

   Tip

   You can enter just: python setup.py test_all instead of the above cmd-line since it has been aliased in the file(setup.cfg) file. Check this file for more example commands to use during development.

4. If you made a rather important modification, update also the doc(CHANGES) file and/or other documents (i.e. README.rst). To see the rendered results of the documents, issue the following commands and read the result html at file(build/sphinx/html/index.html):

   $ python setup.py build_sphinx                  # Builds html docs
   $ python setup.py build_sphinx -b doctest       # Checks if python-code embeded in comments runs ok.

5. If there are no problems, commit your changes with a descriptive message.

6. Repeat this cycle for other bugs/enhancements.

7. When you are finished, push the changes upstream to github and make a merge_request. You can check whether your merge-request indeed passed the tests by checking its build-status on the integration-server’s site (TravisCI).

   Hint

   Skim through the small IPython developer’s documentantion on the matter: The perfect pull request

Specs & Algorithm

This program was implemented from scratch based on this download(GTR specification <23.10.2013 ECE-TRANS-WP29-GRPE-2013-13 0930.docx>) (included in the file(docs/) folder). The latest version of this GTR, along with other related documents can be found at UNECE’s site:

• http://www.unece.org/trans/main/wp29/wp29wgs/wp29grpe/grpedoc_2013.html

• https://www2.unece.org/wiki/pages/viewpage.action?pageId=2523179

• Probably a more comprehensible but older spec is this one: https://www2.unece.org/wiki/display/trans/DHC+draft+technical+report

The WLTC-profiles for the various classes in the file(devtools/data/cycles/) folder were generated from the tables of the specs above using the file(devtools/csvcolumns8to2.py) script, but it still requires an intermediate manual step involving a spreadsheet to copy the table into ands save them as CSV.

Then use the file(devtools/buildwltcclass.py) to construct the respective python-vars into the mod(wltp/model.py) sources.

Data-files generated from Steven Heinz’s ms-access vehicle info db-table can be processed with the file(devtools/preprocheinz.py) script.

Cycles

Development team

• Author:

  • Kostis Anagnostopoulos

• Contributing Authors:

  • Heinz Steven (test-data, validation and review)

  • Georgios Fontaras (simulation, physics & engineering support)

  • Alessandro Marotta (policy support)

Glossary

rubric:

WLTP
    The `Worldwide harmonised Light duty vehicles Test Procedure <https://www2.unece.org/wiki/pages/viewpage.action?pageId=2523179>`_,
    a `GRPE` informal working group

UNECE
    The United Nations Economic Commission for Europe, which has assumed the steering role
    on the `WLTP`.

GRPE
    `UNECE` Working party on Pollution and Energy - Transport Programme

GTR
GTRs
    Any of the *Global Technical Regulation* documents of the `WLTP` .

GS Task-Force
    The Gear-shift Task-force of the `GRPE`. It is the team of automotive experts drafting
    the gear-shifting strategy for vehicles running the `WLTP` cycles.

WLTC
    The family of pre-defined *driving-cycles* corresponding to vehicles with different
    PMR (Power to Mass Ratio). Classes 1,2, 3a & 3b are split in 2, 4, 4 and 4 *parts* respectively.

Unladen mass
    *UM* or *Curb weight*, the weight of the vehicle in running order minus
    the mass of the driver.

Test mass
    *TM*, the representative weight of the vehicle used as input for the calculations of the simulation,
    derived by interpolating between high and low values for the |CO2|-family of the vehicle.

Downscaling
    Reduction of the top-velocity of the original drive trace to be followed, to ensure that the vehicle
    is not driven in an unduly high proportion of "full throttle".

pandas-model
    The *container* of data that the gear-shift calculator consumes and produces.
    It is implemented by class(`wltp.pandel.Pandel`) as a mergeable stack of `JSON-schema` abiding trees of
    strings and numbers, formed with sequences, dictionaries, mod(`pandas`)-instances and URI-references.

JSON-schema
    The `JSON schema <http://json-schema.org/>`_ is an `IETF draft <http://tools.ietf.org/html/draft-zyp-json-schema-03>`_
    that provides a *contract* for what JSON-data is required for a given application and how to interact
    with it.  JSON Schema is intended to define validation, documentation, hyperlink navigation, and
    interaction control of JSON data.
    You can learn more about it from this `excellent guide <http://spacetelescope.github.io/understanding-json-schema/>`_,
    and experiment with this `on-line validator <http://www.jsonschema.net/>`_.

JSON-pointer
    JSON Pointer(rfc(`6901`)) defines a string syntax for identifying a specific value within
    a JavaScript Object Notation (JSON) document. It aims to serve the same purpose as *XPath* from the XML world,
    but it is much simpler.