11 functions with pixel-by-pixel plotting, auto-scaling Y axis, pan/zoom controls, grid and axes

# Function Plotter - NumWorks
# Created by Alvar Laigna - https://alvarlaigna.com
# Arrows:pan/zoom OK:choose Back:back
from kandinsky import fill_rect as F,draw_string as D
from ion import keydown as K
from time import sleep as Z
from math import pi,sqrt,sin,cos,tan,log,exp
SW,SH=320,222
BK=(0,)*3;WH=(255,)*3
BL=(50,110,230);TL=(0,190,190)
YL=(220,200,60);GN=(60,190,60)
DG=(120,)*3
GR=(40,40,40);LG=(30,30,30)
okv=1 if K(4)or K(52) else 0
def okd(): return K(4)or K(52)
def okp():
 global okv
 d=okd()
 if d and not okv:
  okv=1
  return True
 if not d:okv=0
 return False
def wup():
 while okd():Z(0.02)
 Z(0.12)
# Plot area
PL,PT=10,2
PW,PH=300,190
PB=PT+PH
# Function definitions
def f_x2(x):return x*x
def f_x3(x):return x*x*x
def f_sin(x):return sin(x)
def f_cos(x):return cos(x)
def f_tan(x):
 c=cos(x)
 if abs(c)<1e-10:return None
 return tan(x)
def f_inv(x):
 if abs(x)<1e-10:return None
 return 1.0/x
def f_sqrt(x):
 if x<0:return None
 return sqrt(x)
def f_exp2(x):return 2.0**x
def f_abs(x):return abs(x)
FNS=[
 ("x^2",f_x2),
 ("x^3",f_x3),
 ("sin(x)",f_sin),
 ("cos(x)",f_cos),
 ("tan(x)",f_tan),
 ("1/x",f_inv),
 ("sqrt(x)",f_sqrt),
 ("2^x",f_exp2),
 ("|x|",f_abs),
 ("ax2+bx+c",None),
 ("a*sin(bx+c)",None),
]
def get_params(kind):
 F(0,0,SW,SH,BK)
 if kind==0:
  D("Custom Quadratic",10,10,TL,BK)
  D("y = ax^2 + bx + c",10,30,WH,BK)
 else:
  D("Custom Sine Wave",10,10,TL,BK)
  D("y = a*sin(bx + c)",10,30,WH,BK)
 D("Enter a:",10,60,YL,BK)
 a=input()
 D("Enter b:",10,80,YL,BK)
 b=input()
 D("Enter c:",10,100,YL,BK)
 c=input()
 try:
  a,b,c=float(a),float(b),float(c)
 except:
  a,b,c=1.0,0.0,0.0
 return a,b,c
def make_quad(a,b,c):
 def fn(x):return a*x*x+b*x+c
 return fn
def make_asin(a,b,c):
 def fn(x):return a*sin(b*x+c)
 return fn
def draw_axes(xn,xx,yn,yx):
 # Grid lines
 ix=1
 rng=xx-xn
 if rng>20:ix=5
 elif rng>10:ix=2
 iy=ix
 # Vertical grid
 gx=int(xn)-1
 while gx<=int(xx)+1:
  if gx%ix==0:
   px=PL+int((gx-xn)*PW/(xx-xn))
   if PL<=px<PL+PW:
    for yy in range(PT,PB,2):
     F(px,yy,1,1,LG)
  gx+=1
 # Horizontal grid
 gy=int(yn)-1
 while gy<=int(yx)+1:
  if gy%iy==0:
   py=PB-int((gy-yn)*PH/(yx-yn))
   if PT<=py<PB:
    for xx2 in range(PL,PL+PW,2):
     F(xx2,py,1,1,LG)
  gy+=1
 # X axis
 if yn<=0<=yx:
  ay=PB-int((0-yn)*PH/(yx-yn))
  if PT<=ay<PB:
   F(PL,ay,PW,1,DG)
 # Y axis
 if xn<=0<=xx:
  ax=PL+int((0-xn)*PW/(xx-xn))
  if PL<=ax<PL+PW:
   F(ax,PT,1,PH,DG)
 # Origin label
 if xn<=0<=xx and yn<=0<=yx:
  ox=PL+int((0-xn)*PW/(xx-xn))
  oy=PB-int((0-yn)*PH/(yx-yn))
  if PL+5<=ox<PL+PW-10 and PT+2<=oy<PB-12:
   D("0",ox+2,oy+1,DG,BK)
def plot(fn,name,xn,xx,yn,yx):
 F(0,0,SW,SH,BK)
 draw_axes(xn,xx,yn,yx)
 # Plot curve
 pr=-1
 for i in range(PW):
  x=xn+i*(xx-xn)/PW
  try:
   y=fn(x)
   if y is None:
    pr=-1
    continue
   py=PB-int((y-yn)*PH/(yx-yn))
   if PT<=py<PB:
    F(PL+i,py,2,2,TL)
    if pr>=0 and abs(py-pr)>2 and abs(py-pr)<PH:
     mn=min(py,pr);mx=max(py,pr)
     mn=max(mn,PT);mx=min(mx,PB-1)
     for yf in range(mn,mx+1):
      F(PL+i,yf,1,1,TL)
    pr=py
   else:
    pr=-1
  except:
   pr=-1
 # Info bar
 F(0,PB+1,SW,SH-PB-1,BK)
 D("y="+name,5,PB+4,YL,BK)
 rx="x:["+str(round(xn,1))+","+str(round(xx,1))+"]"
 D(rx,160,PB+4,DG,BK)
 D("Arrows:pan/zoom Back:menu",5,PB+18,DG,BK)
def auto_y(fn,xn,xx):
 mn=1e9;mx=-1e9
 for i in range(PW):
  x=xn+i*(xx-xn)/PW
  try:
   y=fn(x)
   if y is None:continue
   if abs(y)>1e6:continue
   if y<mn:mn=y
   if y>mx:mx=y
  except:
   pass
 if mn>=mx:mn=-5;mx=5
 mg=(mx-mn)*0.15
 if mg<0.5:mg=0.5
 return mn-mg,mx+mg
def viewer(fn,name):
 xn,xx=-5.0,5.0
 yn,yx=auto_y(fn,xn,xx)
 plot(fn,name,xn,xx,yn,yx)
 wup()
 while True:
  mv=False
  dx=(xx-xn)*0.15
  if K(0):
   xn-=dx;xx-=dx;mv=True
  if K(3):
   xn+=dx;xx+=dx;mv=True
  if K(1):
   cx=(xn+xx)/2;cy=(yn+yx)/2
   hw=(xx-xn)*0.35;hh=(yx-yn)*0.35
   xn=cx-hw;xx=cx+hw
   yn=cy-hh;yx=cy+hh
   mv=True
  if K(2):
   cx=(xn+xx)/2;cy=(yn+yx)/2
   hw=(xx-xn)*0.65;hh=(yx-yn)*0.65
   xn=cx-hw;xx=cx+hw
   yn=cy-hh;yx=cy+hh
   mv=True
  if K(17):
   Z(0.2);return
  if mv:
   plot(fn,name,xn,xx,yn,yx)
   Z(0.12)
  Z(0.03)
def menu():
 items=["x^2","x^3","sin(x)","cos(x)","tan(x)",
  "1/x","sqrt(x)","2^x","|x|","ax2+bx+c","a*sin(bx+c)"]
 N=len(items)
 sel=0
 sc=0
 VIS=9
 def draw_menu():
  F(0,0,SW,SH,BK)
  D("Function Plotter",60,5,TL,BK)
  D("Select function:",10,28,DG,BK)
  for i in range(VIS):
   idx=sc+i
   if idx>=N:break
   y=45+i*19
   if idx==sel:
    F(5,y-1,310,18,BL)
    D("y = "+items[idx],15,y,WH,BL)
   else:
    D("y = "+items[idx],15,y,WH,BK)
  D("OK:select Back:quit",60,SH-16,DG,BK)
 draw_menu()
 wup()
 while True:
  r=False
  if K(2):
   if sel<N-1:
    sel+=1
    if sel>=sc+VIS:sc+=1
    r=True
  if K(1):
   if sel>0:
    sel-=1
    if sel<sc:sc-=1
    r=True
  if okp():
   wup()
   if sel<9:
    fn=FNS[sel][1]
    nm=items[sel]
    viewer(fn,nm)
    draw_menu();wup()
   elif sel==9:
    a,b,c=get_params(0)
    fn=make_quad(a,b,c)
    nm=str(a)+"x2+"+str(b)+"x+"+str(c)
    viewer(fn,nm)
    draw_menu();wup()
   elif sel==10:
    a,b,c=get_params(1)
    fn=make_asin(a,b,c)
    nm=str(a)+"sin("+str(b)+"x+"+str(c)+")"
    viewer(fn,nm)
    draw_menu();wup()
  if K(17):
   Z(0.2);return
  if r:
   draw_menu()
   Z(0.15)
  Z(0.03)
def run():
 menu()
run()