Udpated

constants.py

@@ -1,3 +1,4 @@
 PLOT_HEIGHT = 400
 PLOT_WIDTH = 400
+PLOT_PADDING = 20
 TICK_LENGTH = 5

movement.py

@@ -1,6 +0,0 @@
-from turtle import *
-
-def flyto(x, y):
-    penup()
-    goto(x, y)
-    pendown()

plotting.py

@@ -0,0 +1,48 @@
+# plotting.py
+# ------------
+# By MWC Contributors
+# The functions in this module draw parts of a scatter plot. 
+# These functions are all complete; you don't need to edit this file.
+
+from turtle import *
+import constants
+
+def flyto(x, y):
+    penup()
+    goto(x, y)
+    pendown()
+
+def prepare_screen():
+    """Sets up the screen for a plot.
+    """
+    screensize(constants.PLOT_WIDTH, constants.PLOT_HEIGHT)
+    setworldcoordinates(
+        -constants.PLOT_PADDING, 
+        -constants.PLOT_PADDING, 
+        constants.PLOT_WIDTH + constants.PLOT_PADDING,
+        constants.PLOT_HEIGHT + constants.PLOT_PADDING,
+    )
+
+def draw_point(x, y, color, size):
+    "Draws a dot at (x, y) screen position, using the color and size provided."
+    flyto(x, y)
+    dot(size, color)
+
+def draw_x_axis():
+    flyto(0, 0)
+    goto(constants.PLOT_WIDTH, 0)
+
+def draw_y_axis():
+    flyto(0, 0)
+    goto(0, constants.PLOT_HEIGHT)
+
+def draw_y_tick(position, label):
+    flyto(0, position)
+    goto(-constants.TICK_LENGTH, position)
+    write(label, align='right')
+
+def draw_x_tick(position, label):
+    flyto(position, 0)
+    goto(position, -constants.TICK_LENGTH)
+    flyto(position, -constants.TICK_LENGTH - 10)
+    write(label, align='center')

scatterplot.py

@@ -1,22 +1,31 @@
-# What needs to be taught?
-# - return values
-#   - unpacking multiple return values 
-# - list comprehensions
-# - named function arguments
-#   - after positional
-#   - like dictionaries
-#   - 
-# - modules
-
-# Parameters: 
-# - the actual drawing will be 
+# scatterplot.py
+# ------------
+# By MWC Contributors
+# Uses lots of helper functions in other modules to draw a scatter plot.
 
 from turtle import *
-from math import floor, ceil, log
-import constants
-from movement import flyto
 from superturtle.movement import no_delay
+import constants
 from generate_data import generate_data
+from ticks import get_tick_values
+from plotting import (
+    prepare_screen, 
+    draw_x_axis, 
+    draw_y_axis,
+    draw_x_tick, 
+    draw_y_tick,
+    draw_point, 
+)
+from transform import (
+    maximum, 
+    minimum,
+    bounds, 
+    clamp,
+    ratio, 
+    scale,
+    get_x_values,
+    get_y_values,
+)
 
 def draw_scatterplot(data, size=5, color="black"):
     "Draws a scatter plot, showing the data"
@@ -24,90 +33,14 @@ def draw_scatterplot(data, size=5, color="black"):
     draw_axes(data)
     draw_points(data, color, size)
 
-def prepare_screen():
-    """Sets up the 
-    """
-    screensize(400, 400)
-    setworldcoordinates(-20, -20, 420, 420)
-
 def draw_axes(data):
-    """Draws the scatter plot's axes.
-    """
-    flyto(0, 0)
-    goto(0, constants.PLOT_HEIGHT)
-    flyto(0, 0)
-    goto(constants.PLOT_WIDTH, 0)
-
-    y_values = get_y_values(data)
-    ymin, ymax = get_bounds(y_values)
-    draw_y_tick(0, ymin)
-    draw_y_tick(constants.PLOT_HEIGHT, ymax)
-    for tick in get_tick_range(y_values):
-        position = scale(tick, ymin, ymax, 0, constants.PLOT_HEIGHT)
-        draw_y_tick(position, tick)
-
-    x_values = get_x_values(data)
-    xmin, xmax = get_bounds(x_values)
-    draw_x_tick(0, xmin)
-    draw_x_tick(constants.PLOT_WIDTH, xmax)
-    for tick in get_tick_range(x_values):
-        position = scale(tick, xmin, xmax, 0, constants.PLOT_WIDTH)
-        draw_x_tick(position, tick)
-
-def get_tick_range(values):
-    "Returns a range of positions for ticks"
-    vmin, vmax = get_bounds(values)
-    tick_interval = get_tick_interval(values)
-    first_tick = ceil(vmin / tick_interval) * tick_interval
-    print(tick_interval)
-    print(first_tick)
-    print(vmax)
-    return range(first_tick, vmax, tick_interval)
-
-def get_tick_interval(values):
-    ""
-    vmin, vmax = get_bounds(values)
-    log_span = log(vmax - vmin, 10)
-    return 10 ** floor(log_span)
+    "Draws the scatter plot's axes."
 
 def draw_points(data, color, size):
-    xmin, xmax = get_bounds(get_x_values(data))
-    ymin, ymax = get_bounds(get_y_values(data))
-    for x, y in data:
-        sx = scale(x, xmin, xmax, 0, constants.PLOT_WIDTH)
-        sy = scale(y, ymin, ymax, 0, constants.PLOT_HEIGHT)
-        draw_point(sx, sy, color, size)
-
-def draw_point(x, y, color, size):
-    flyto(x, y)
-    dot(size, color)
-
-def get_bounds(data):
-    return min(data), max(data)
-
-def get_x_values(data):
-    return [x for x, y, in data]
-
-def get_y_values(data):
-    return [y for x, y in data]
-
-def draw_y_tick(position, label):
-    flyto(0, position)
-    goto(-constants.TICK_LENGTH, position)
-    write(label, align='right')
-
-def draw_x_tick(position, label):
-    flyto(position, 0)
-    goto(position, -constants.TICK_LENGTH)
-    flyto(position, -constants.TICK_LENGTH - 10)
-    write(label, align='center')
-
-def scale(value, domain_min, domain_max, range_min, range_max):
-    ratio = (value - domain_min) / (domain_max - domain_min)
-    return range_min + ratio * (range_max - range_min)
+    "Draws the scatter plot's points."
 
 with no_delay():
     data = generate_data(50, 10, 500, 5, 400, 1000)
     draw_scatterplot(data, size=5, color="blue")
     hideturtle()
-input()
+done()

test_transform.py

@@ -0,0 +1,34 @@
+from transform import (
+    maximum, 
+    minimum,
+    bounds, 
+    clamp,
+    ratio, 
+    scale,
+    get_x_values,
+    get_y_values,
+)
+
+def test(function, arguments, expected):
+    observed = function(*arguments)
+    if observed != expected:
+        args = ', '.join(str(arg) for arg in arguments) 
+        print(f"Error: Expected {function}({args}) to equal {expected}, but it was {observed}")
+
+test(maximum, [[0, 1, 2, 3]], 3)
+test(maximum, [[-10, -20, -30]], -10)
+test(minimum, [[0, 1, 2, 3]], 0)
+test(minimum, [[-10, -20, -30]], -30)
+test(bounds, [[0, 1, 2, 3]], [0, 3])
+test(bounds, [[-10, -20, -30]], [-30, -10])
+test(clamp, [[10, 0, 100]], 10)
+test(clamp, [[-10, 0, 100]], 0)
+test(clamp, [[104, 0, 100]], 100)
+test(ratio, [[5, 0, 10]], 0.5)
+test(ratio, [[167, 100, 200]], 0.67)
+test(ratio, [[8, 10, 0]], 0.2)
+test(ratio, [[4, 10, 20]], 0.0)
+test(scale, [[4, 0, 10, 0, 100]], 40)
+test(scale, [[160, 120, 240, 0, 100]], 100/3)
+test(get_x_values, [[[0, 5], [1, 5], [2, 5]]], [0, 1, 2])
+test(get_y_values, [[[0, 5], [1, 5], [2, 5]]], [5, 5, 5])

ticks.py

@@ -0,0 +1,26 @@
+# ticks.py
+# ------------
+# By MWC Contributors
+# The functions in this module calculate suitable placements 
+# for ticks on a plot axis which will display values. 
+# These functions are all complete; you don't need to edit this file.
+
+from math import floor, ceil, log
+from transform import bounds
+
+def get_tick_values(low, high):
+    """Returns a list of values to use for ticks (labeled points along an axis). 
+    Includes the lowest value, a bunch of "nice" intermediate values, and the highest value.
+    """
+    tick_interval = get_tick_interval(high - low)
+    first_tick = ceil(low / tick_interval) * tick_interval
+    return [low] + list(range(first_tick, high, tick_interval)) + [high]
+
+def get_tick_interval(span):
+    """Returns a 'nice' interval for ticks across span.
+    The interval is a power of ten (e.g. 1000, 100, 0.1)
+    scaled so that there will be between 0 and 10 internal ticks.
+    """
+    log_span = log(span, 10)
+    return 10 ** floor(log_span)
+

transform.py

@@ -0,0 +1,45 @@
+# transform.py
+# ------------
+# By MWC Contributors
+# The functions in this module transform data. 
+# None of them are finished; this is your job!
+
+def maximum(data):
+    "Returns the largest number in data"
+    raise NotImplementedError
+
+def minimum(data):
+    "Returns the smallest number in data"
+    raise NotImplementedError
+
+def bounds(data):
+    "Returns a list of the largest and smallest numbers in data"
+    raise NotImplementedError
+
+def clamp(value, low, high):
+    """Clamps a value to a range from low to high. 
+    Returns value if it is between low and high.
+    If value is lower than low, returns low. If value is higher than high, returns high.
+    """
+    raise NotImplementedError
+
+def ratio(value, start, end):
+    """Returns a number from 0.0 to 1.0, representing how far along value is from start to end.
+    The return value is clamped to [0, 1], so even if value is lower than start, the return 
+    value will not be lower than 0.0.
+    """
+    raise NotImplementedError
+
+def scale(value, domain_min, domain_max, range_min, range_max):
+    "Given a value within a domain, returns the scaled equivalent within range."
+    ratio = (value - domain_min) / (domain_max - domain_min)
+    return range_min + ratio * (range_max - range_min)
+    raise NotImplementedError
+
+def get_x_values(points):
+    "Returns the first value for each point in points."
+    raise NotImplementedError
+
+def get_y_values(points):
+    "Returns the second value for each point in points."
+    raise NotImplementedError