At My Fingertips
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Switzerland has an extensive hiking trail network with 65000 kilometers of signed hiking trails. There are three kinds of trails: hiking trails (marked in yellow), mountain hiking trails (marked in yellow-red-white), and alpine hiking trails (marked in white and blue).
The trails are signed with four kinds of signs, amongst them hiking signposts.
Let's compose those signs with PyTamaro! Before doing this activity you should do the Swiss Hiking Direction Pointers activity, as you will need to reuse some functions that you have developed there.
The hiking signpost colors are specified in the handbook of hiking trail signage, and are the following:
Let's assign these colors to variables in our code below. This way instead of generating the color every time it's needed, you can just use one of the variables that holds its value.
The official measurements for the signpost are specified in the handbook of hiking trail signage.
As you can see the measurements for signs with a different number of destinations don't always follow logical rules.
For example, the width of the sign is always the same, but the height sometimes changes.
Let's start by creating constants for the values that remain constant in all signposts.
The variable aspects are:
Let's represent these mappings using dictionaries. In python, a dictionary is a data structure that stores pairs composed by keys and their corresponding values. In a Python dictionary, you use a key to quickly find its associated value.
Fill the incomplete dictionaries below and check out how they are used!
On the signpost, destinations are indicated from the top to the bottom, and the maximum number of destinations per signpost is 4. They are divided in 3 categories:
Nearest Destination:
Corresponds to the nearest intermediate destination and is listed at the top of the signpost
Intermediate Destinations:
Places of greater importance, interfaces with public transport, important junctions and intersections of routes
Route Destination:
Corresponds to the end of the route and is listed at the bottom of the signpost.
To each destination is assigned a distance represented in terms of hours and minutes.
How can we represent a destination in terms of its name and distance?
We can use a data class. In Python, a data class is a special type of class that is primarily
used to store and manage data. You can create a data class using the @dataclass
decorator
from the dataclasses
module.
The code below defines a dataclass that can be used to represent destinations:
Let's implement a collection of small reusable functions to simplify our complex problem.
render_text
FunctionThe render_text
function should generate an
image where the given content
is rendered as text
of the given text_color
with size points
on a background of color background_color
of the
exact same size of the rendered text.
The font of the text should be "ASTRA-frutiger standard", as specified by the original documentation, but due to its rarity it is not available for our text function. Use the font "Roboto Condensed" instead, it is quite similar but still not the same.
Hint: you can also implement a get_background
function,
whose purpose is to generate a rectangle with the wanted color
,
with the same width and height of the given graphic
:
you will find it useful in the future!
You can use graphic_width and graphic_height.
render_time
FunctionEach destination has a time information specifying the distance. The time (units h, min) is rounded to 5 min. Starting from a time specification of three hours, specifications with x h 5 min or x h 55 min are rounded to the full hour.
The render_time
function should generate an
image where the given minutes
are rendered as text of the given text_color
on a background with color background_color
of the exact same size of the rendered text.
Ensure that the specifications described are satisfied, by making the correct roundings.
Zeros are not represented, instead the time should be left empty.
Hint: you can convert integers to strings using the python str(integer_value)
function!
You can implement the functions suggested below, or come up with your own.
render_destination
FunctionImplement the render_destination
function so that it returns a graphic representing the
given object of type Destination
.
Remember that Destination
is a dataclass with attributes name
and duration_minutes
.
The text should be of the given text_color
and have size of the constant content_points
px
(we assigned a value to it at the beginning of the activity!).
A route is a list of destinations, ordered from closest destination to the final route destination.
render_route
FunctionImplement the render_route
function so that it returns a graphic representing
the given list of destinations.
Notice that the result has no empty space on the top or bottom!
separator
FunctionThere can be multiple routes developing from a location (maximum four), and they can be represented on a signpost separated by a route separation dash.
The separator
function should return a horizontal separation line of the given text_color
,
on a background of the given width
, height
and background_color
.
On a signpost there can be just one route or multiple (maximum 4). Each route is a list of destinations, and the maximum number of destinations on a signpost is 4.
render_routes
FunctionImplement the render_routes
function that renders the given list of routes route_list
, where each route is
separated by a separator.
Notice that route_list
is a list of routes, therefore a list of lists of destinations (routes).
The result should be enclosed between a top gap and a bottom gap of the given gap_height
. There should be gaps on the sides as well,
width gap_height
as their width.
IMPORTANT: note that the total width of the result should be width
, therefore the width of the text part
should be
width - 2 * gap_height
The location field of a signpost informs about the altitude above sea level and the location name of where the signpost is located.
These are the measurements
location_info
FunctionThe location_info
function should generate a location field with the given location
.
You are given a Location
dataclass to contain the location's information.
The background color should be traffic_white
and the text color should be black
.
The points
of the text should measure
location_points
(defined at the beginning of the activity),
and between the location
name
and the location altitude
there should be a gap with height 16
.
The hiking trail signpost is a yellow sign.
You have developed a right_sign
function in the
Swiss Hiking Direction Pointers, that allows you to generate a sign with the wanted width
, height
, point_width
and color
.
Import the right_sign
function using your toolbox, and
combine it with the render_routes
function and the location_info
function,
to generate a hiking trail signpost with the wanted information.
Use the official measurements, assigned to constants and dictionaries at the beginning of the activity, in the Measurements section.
Also implement the count_destinations
function that takes a list of routes
and returns the total number of destinations in the routes.
Use it to assert the number of destinations is maximum 4 and minimum 1.
The mountain trail signpost is a yellow sign with a white-red-white point.
You have developed a striped_right_sign
function in the
Swiss Hiking Direction Pointers, that allows you to generate a sign
with the wanted width
, height
, point_width
, arrow_height
,
body_color
and arrow_color
(The body_color
is the
color of the rectangular part of the sign).
Import the striped_right_sign
function using your toolbox,
and combine it with the render_routes
function and the location_info
function,
to generate a mountain trail signpost with the wanted information.
Use the official measurements, assigned to constants and dictionaries at the beginning of the activity, in the Measurements section.
Use the count_destinations
function you implemented to ensure that
the number of destinations is between 1 and 4.
The red color is constant traffic_red
.
The alpine trail signpost is very similar to the mountain trail one, except it is blue with a white-blue-white point.
Use the striped_right_sign
function you imported from toolbox,
the render_routes
function and the location_info
function,
to generate a alpine trail signpost with the wanted information,
pointing to the wanted direction (right if parameter right
is True
)
Use the official measurements, assigned to constants and dictionaries at the beginning of the activity, in the Measurements section.
Use the count_destinations
function you implemented to ensure that
the number of destinations is between 1 and 4.
The blue color is constant sky_blue
. Note that the text is written in traffic_white
!
You learned about one type of signage you encounter on the Swiss hiking trail network.xw
You also (hopefully) practiced to structure your code so you can reuse functionality. Implementing all those helper functions in the beginning may have seemed useless or confusing, but in the end it allowed you to decompose a bigger problem into simpler and reusable code.
This activity has been created by LuCE Research Lab and is licensed under CC BY-SA 4.0.
Swiss Hiking Signposts
PyTamaro is a project created by the Lugano Computing Education Research Lab at the Software Institute of USI
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