File:Quadratic-function-x2-minus4x-plus2.svg
Summary
| Description |
English: Quadratic function f(x) := x2−4x+2. |
| Date | |
| Source | Own work |
| Author | Rumil |
Licensing
I, the copyright holder of this work, hereby publish it under the following license:
  |
This file is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication. |
| The person who associated a work with this deed has dedicated the work to the public domain by waiving all of their rights to the work worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law. You can copy, modify, distribute and perform the work, even for commercial purposes, all without asking permission.
|
Source code
import numpy as np
from numpy import arange, array
import matplotlib as mp
import matplotlib.pyplot as pyplot
minus = u"\u2212"
blue = [0.2,0.4,0.6,1.0]
green = [0,0.46,0,0.8]
magenta = [0.6,0,0.4,0.8]
axes_color = "#505050"
def label_to_str(x):
if type(x) is str:
return x
else:
return minus+str(abs(x)) if x<0 else str(x)
def arrow(ax,x,y,dx,dy,lw=2,w=1,h=1):
ax.arrow(x,y,dx,dy, shape='full', lw=lw, length_includes_head=True,
head_width=0.22*w, head_length=0.5*h, color=axes_color,
joinstyle='bevel', clip_on=False)
def plot(f,X=[-5,5],Y=[-5,5],name="plot",inc=1,incy=None,aspect=1,xticks=[],yticks=[],
xsize=None, xshift=[0,0],yshift=[0,0], out=False, ticks_off=False,
con=0.5,dx=0.01,lw_line=2.6,color=blue,xlabels=False,ylabels=False):
lw_grid = 1.8
fontsize = 14
if xsize is None: xsize = abs(X[1]-X[0])
if incy is None: incy = inc
style = {
"axes.linewidth": lw_grid,
"grid.linewidth": lw_grid,
"grid.linestyle": "solid",
"grid.color": "#e0e0da",
"lines.linewidth": 2,
# "lines.markersize": 10,
"xtick.labelsize": 12,
"ytick.labelsize": 12,
"figure.figsize": (4*xsize/8,20)
}
mp.rcParams.update(style)
fig = pyplot.figure()
ax = fig.add_subplot(1,1,1)
ax.spines['bottom'].set_color(axes_color)
ax.spines['top'].set_color(axes_color)
ax.spines['right'].set_color(axes_color)
ax.spines['left'].set_color(axes_color)
ax.spines['bottom'].set_zorder(2)
ax.spines['top'].set_zorder(2)
ax.spines['right'].set_zorder(2)
ax.spines['left'].set_zorder(2)
ax.spines['top'].set_color('none')
ax.spines['right'].set_color('none')
ax.xaxis.set_ticks_position('bottom')
ax.yaxis.set_ticks_position('left')
if not out:
ax.spines['bottom'].set_position('zero')
ax.spines['left'].set_position('zero')
ax.xaxis.grid()
ax.yaxis.grid()
ax.set_axisbelow(True)
ax.xaxis.set_tick_params(width=lw_grid, length=10,
pad=8,color=axes_color,direction='inout')
ax.yaxis.set_tick_params(width=lw_grid, length=10,
pad=8,color=axes_color,direction='inout')
ax.set_aspect(aspect)
ax.axis(X+Y)
if out:
ax.set_xticks(list(arange(X[0],X[1]+inc,inc)))
ax.set_yticks(list(arange(Y[0],Y[1]+incy,incy)))
else:
ax.set_xticks(list(arange(X[0],0,inc))+xticks+list(arange(inc,X[1]+inc,inc)))
ax.set_yticks(list(arange(Y[0],0,incy))+yticks+list(arange(incy,Y[1]+incy,incy)))
if xlabels is not False:
ax.set_xticklabels([label_to_str(x) for x in xlabels])
if ylabels is not False:
ax.set_yticklabels([label_to_str(y) for y in ylabels])
a = f if type(f) is list else [f]
for f in a:
x = arange(X[0], X[1], dx)
y = array(map(f,x))
pos = np.where(np.abs(np.diff(y)) >= con)[0]+1
x = np.insert(x, pos, np.nan)
y = np.insert(y, pos, np.nan)
ax.plot(x,y, color=color, zorder=3,linewidth=lw_line)
xposx = X[1]+(xshift[0]-0.5)*inc; xposy = (xshift[1]-0.68)*incy
yposx = (yshift[0]+0.28)*inc; yposy = Y[1]+(yshift[1]-0.55)*incy
if out:
xposy = Y[0]+(xshift[1]-0.5)*incy
yposx = X[0]+(yshift[0]-0.5)*inc
else:
arrow(ax,X[1]-inc,0,1,0,lw=lw_grid,w=incy,h=incy*aspect)
arrow(ax,0,Y[1]-incy,0,incy,lw=lw_grid,w=incy*aspect,h=incy)
ax.text(xposx,xposy,"x",fontsize=fontsize,style="italic",color="#202020")
ax.text(yposx,yposy,"y",fontsize=fontsize,style="italic",color="#202020")
# pyplot.savefig(name+".png",bbox_inches='tight')
pyplot.savefig(name+".svg",bbox_inches='tight')
plot(lambda x: x*x-4*x+2, [-2,5], [-4,4], "plot",
xlabels=["",-1,1,2,3,4],
ylabels=["",-3,-2,-1,1,2,3])