turtleplot.py

# -*- coding: utf-8 -*-
"""
Created on Tue Dec  1 18:34:46 2020

@author: Roneet
"""

import matplotlib.pyplot as plt
import numpy as np

def turtlePlot(turtleCommands):
    
    # TURTLEPLOT Creates and displays a matplotlib pyplot based on the 
    # turtleCommands. 
    #
    # Usage: turtlePlot(turtleCommands)
    #
    # Takes an array 'turtleCommands' generated by the turtleGraph function as
    # an argument. Calculates X and Y coordinates for points, which are passed 
    # to the matplotlib.pyplot.plot function as two arrays, one for X and one
    # for Y coordinates. 
    #
    # Author: Roneet V. Nagale, s204091@dtu.dk, 2020
    
    angleSpecArray = []
    
    # Initialize an array of direction-vectors with an initial vector (1,0), 
    # the canonical basis vector.
    arrayOfDirections=np.array([[1,0]])
    
    # Initialize an array if points with the origin for the planar coordinate-
    # system.
    arrayOfPoints=np.array([[0,0]])
    
    # Assign the length specification to a variable. It is the 0th element of 
    # the turtleCommands array (as well as all elements with even indices). 
    # Because of how it's calculated in the turtleGraph function, the length
    # specification is constant throughout the turtleCommands array and thus
    # only needs to be read once.
    lengthSpec=turtleCommands[0]
    
    #Based on the structure of the turtleCommands array, create a new array
    #with only the angle specifications (elements of the turtleCommands array
    # with odd indices). 
    for specIndex in range(0, len(turtleCommands)):
        
        if specIndex%2 != 0:
            angleSpecArray=np.append(angleSpecArray, turtleCommands[specIndex])
    
    # Use the array of angle specifications, iterate through it using a for 
    # loop and calculate the values of new points. 
    for angleSpec in angleSpecArray:  
        
        # Pick the last/latest added element in the array of points.
        currentPoint=arrayOfPoints[-1]
        
        # Calculate a new point, based on the current point, the length 
        # specification and the latest direction vector in the array of 
        # directions. 
        newPoint = currentPoint+lengthSpec*arrayOfDirections[-1]
        
        # Add the new point to the array of points.
        arrayOfPoints=np.vstack((arrayOfPoints, newPoint))
        
        # Calculate a new direction, by taking a dot product of a matrix of
        # cosine, -sine, sine and cosine of the angle specification, with
        # the last direction vector recorded in the array of directions. 
        newDirection=np.array([np.dot([[np.cos(angleSpec),-np.sin(angleSpec)],
                   [np.sin(angleSpec),np.cos(angleSpec)]],arrayOfDirections[-1])])
        
        # Add the new direction vector to the array of directions. Reiterate
        # loop until all angle specifications are used.
        arrayOfDirections=np.vstack((arrayOfDirections, newDirection))
    
    # After the loop is done and the array of points is filled, add an ending
    # point, based again on the canonincal basis vector and the latest point
    # added to the array of points. (*This might not be the correct solution
    # to have the graph appear symmetrical)
    arrayOfPoints=np.vstack((arrayOfPoints, arrayOfPoints[-1]+lengthSpec*
                             arrayOfDirections[0]))
    
    # Transpose the array of points (which are arrays themselves), to split it
    # into an array of X values and an array of Y values.
    plotArray = np.transpose(arrayOfPoints)

    # Pass the two arrays of X and Y values to the matplotlib.pyplot.plot 
    # function, and show the plot. 
    plt.plot(plotArray[0], plotArray[1])  
    #Save the figure to a variable, as it is deleted once plt.show() is called.
    currentFigure = plt.gcf()
    plt.show()
    #Give the user an option to save the plot.
    while True:
        saveChoice = input("""Do you want to save the figure?
                             (Input 1 to save, else press return to skip.)
                             (Note: There is no check in place for existing
                              files. Choose a new name each time to avoid 
                              overwriting.)
                             """)
   
        if saveChoice == '1':
        
            filename = input("Please name the file.")
            
            try: 
                filename = str(filename)
            except:
                print("Please enter a string!")
                continue
            else:
                try:
                    currentFigure.savefig(filename+".svg")
                except: 
                    print("Unable to save file.")
                else:
                    print("Saved successfully to "+filename+".svg")
                    break
        else: 
            break

    input("Returning to main menu.")
    return