import string

import pylab as plt

#Number line plotting with matplotlib.

#TODO

#Allow "barbell" plots like 2<x<4 or x<2 *intersection* x>4

class number_line(object):

def __init__(self, radius=10, tickmarks = 20):

self.radius = radius

self.span = radius * 1.1 #total span of the graph. leaves room for arrows

self.ceil = radius + 1 #if a plot goes to this point it means it is going to infinity

self.floor = -radius - 1 #if a plot goes to this point it means it is going to negative infinity

self.num_tickmarks = tickmarks

#constants

self.black_linewidth = 3

self.red_linewidth = 3

self.arrow_width = 3

self.circle_size = 11.5

self.circle_edge_width = 1.5

self.setup()

self.drawLine()

def setup(self):

#whole background is white

self.fig1 = plt.figure( facecolor='white')

#frame is hidden

self.ax = plt.axes(frameon=False)

# turn off y axis

self.ax.axes.get_yaxis().set_visible(False)

#disable ticks at top of plot

self.ax.get_xaxis().tick_bottom()

#sets ticks on bottom to blank

self.ax.axes.get_xaxis().set_ticks([])

# sets dimensions of axes

plt.axis([-self.span, self.span, -1, 1])

#draws the number line

def drawLine(self):

#plot the main line (slightly crooked so svg will render in webkit)

plt.plot([-self.radius,self.radius],[0,0.001],'k',linewidth=self.black_linewidth,zorder=1)

#find the interval for tickmarks/labels (divide by two to account for negative numbers)

tickmark_interval = self.radius/ (self.num_tickmarks/2)

#draw in appropriate places tick marks and labels

for i in [num for num in range(-self.radius,self.radius+1) if not num % tickmark_interval] :

length = .03

tick_y = -.1

if i==0:

length=.05

tick_y = -.13

#plot the tick marks (slightly crooked so svg will render in webkit)

plt.plot([i,i-.001],[-length,length],'k',linewidth=2, zorder=1)

#write the labels

plt.text(i,tick_y,str(i),horizontalalignment='center')

#draw the arrows

self.arrow((self.span,0),'k',facingRight = True)

self.arrow((-self.span,0),'k',facingRight = False)

#draw arrow on plot

def arrow(self, coord, color,facingRight=True):

tilt = 20 #horizontal left

if facingRight:

tilt = -20 #horizontal right

#use annotate to draw arrow

plt.annotate('', xy=coord, xycoords='data',

xytext=(tilt, 0), textcoords='offset points',

arrowprops=dict(arrowstyle="->", linewidth=self.arrow_width , mutation_scale=18,color=color))

#graph a series of inequalities

def graph(self, equations):

#make so the loop won't go through if equations is a string

if isinstance(equations, str):

equations = [equations]

#get coordinates to graph

toGraph = []

for eq in equations:

toGraph = self.solve(eq,toGraph)

for piece in toGraph:

#if this piece of the graph is a point

if len(piece)==1:

self.plot_point(piece)

#if this piece of the graph is a line

elif len(piece)==2:

#if line going to negative infinity with arrow draw

if piece[0]==self.floor:

plt.plot([piece[1]],[0],'or',markerfacecolor='white',markeredgecolor='r',markersize = self.circle_size, markeredgewidth = self.circle_edge_width, zorder=10)

plt.plot([-self.radius,piece[1]],[0,0],'-r',linewidth=self.red_linewidth,zorder=5)

self.arrow((-self.span,0),'r',facingRight = False)

#if line going to positive infinity with arrow

if piece[1]==self.ceil:

plt.plot([piece[0]],[0],'or',markerfacecolor='white',markeredgecolor='r',markersize = self.circle_size, markeredgewidth = self.circle_edge_width,zorder=10)

plt.plot([piece[0],self.radius],[0,0],'-r',linewidth=self.red_linewidth,zorder=5)

self.arrow((self.span,0),'r',facingRight = True)

for piece in toGraph:

#if this piece of the graph is a point

if len(piece)==1:

plt.plot(piece,[0],'or', markersize = self.circle_size, markeredgewidth = self.circle_edge_width, zorder=10)

#if this piece of the graph is a line

elif len(piece)==2:

#if line going to negative infinity with arrow draw

if piece[0]==self.floor:

plt.plot([piece[1]],[0],'or',markerfacecolor='white',markeredgecolor='r',markersize = self.circle_size, markeredgewidth = self.circle_edge_width, zorder=10)

plt.plot([-self.radius,piece[1]],[0,0],'-r',linewidth=self.red_linewidth,zorder=5)

self.arrow((-self.span,0),'r',facingRight = False)

#if line going to positive infinity with arrow

if piece[1]==self.ceil:

plt.plot([piece[0]],[0],'or',markerfacecolor='white',markeredgecolor='r',markersize = self.circle_size, markeredgewidth = self.circle_edge_width,zorder=10)

plt.plot([piece[0],self.radius],[0,0],'-r',linewidth=self.red_linewidth,zorder=5)

self.arrow((self.span,0),'r',facingRight = True)

#graphs a single point

def plot_point(self, p):

plt.plot(p,[0],'or', markersize = self.circle_size, markeredgewidth = self.circle_edge_width, zorder=10)

#graph a series of points

def plot_points(self, points):

for p in points:

self.plot_point(p)

#Turns an equation into coordinates to plot

def solve(self,eq, toGraph):

if '>' in eq:

toGraph.append([self.getAfter(eq,'>') , self.ceil])

elif '<' in eq:

toGraph.append([self.floor,self.getAfter(eq,'<')])

if '=' in eq:

toGraph.append([self.getAfter(eq,'=')])

return toGraph

#gets float of text in a string after the <, >, <=, or >= sign to help solve equation

def getAfter(self,s, splitchar ):

if'>=' in s:

splitchar = '>='

if '<=' in s:

splitchar = '<='

#check if number is valid

try:

number = float(string.split(s, splitchar)[-1])

except ValueError:

raise Exception("Error parsing equations. Make sure they are of the format x>1 where x is any variable and 1 is any number")

#check if within bounds

if number < -self.radius or number > self.radius:

raise Exception ("Some points are outside the number line's bounds. Try increasing the radius of the number line or choosing values inside the current radius.")

return number

#save figure to specified location

def save(self, filepath, format='png', transparent = True):

plt.savefig(filepath, format = format, bbox_inches ='tight',transparent = transparent)

#clears anything that is graphed

def clear(self):

plt.close()

self.setup()

self.drawLine()