Non-corso Python Esercizi di lettura
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Chi ha difficolta' a scrivere codice Python puo' provare a fare questi esercizi di "lettura" di codice Python.
Gli esercizi proposti sono programmi funzionanti.
Come svolgimento dell'esercizio si deve:
- determinare lo scopo del programma
- spiegare il significato di ogni riga (non banale) del codice
1
def dd(s):
d,m,y=s.split('.')
d,m,y=int(d),int(m),int(y)
md=[0,31,28,31,30,31,30,31,31,30,31,30,31]
if y % 4 == 0: md[2]=29
dy=d
for i in range(1,m):
dy += md[i]
return dy
if __name__=="__main__":
data=input("Dammi una data (es. 14.03.2014) ")
print("il risultato della funzione misteriosa e' ",dd(data))
2
def imin(l):
im,mn=0,l[0]
for i in range(1,len(l)):
if l[i]<mn: im,mn=i,l[i]
return im
if __name__="__main__":
l=input('dammi in input una lista di elementi (es: [1,2,3]): ')
print("l'output della funzione misteriosa e': ",imin(l))
3
def r13(s):
e=''
for c in s:
if 'A'<=c<='Z':
e+=chr(((ord(c)-ord('A'))+13)%26+ord('A'))
elif 'a'<=c<='z':
e+=chr(((ord(c)-ord('a'))+13)%26+ord('a'))
else:
e+=c
return e
if __name__=="__main__":
s=input("scrivi una semplice frase (es: 'Ciao Mondo') ")
r=r13(s)
print("il risultato della funzione misteriosa e': ",r)
print("consiglio: prova a eseguire nuovamente il programma scrivendo")
print("la frase: ",r)
4
def pf(n):
f=[]
for i in range(2,n+1):
while n % i == 0:
f.append(i)
n //= i
if n == 1:
break
return f
if __name__=="__main__":
n=int(input("dammi un numero (consigliato da 2 a 1000): "))
print("il risultato della funzione misteriosa e' ",pf(n))
5
(richiede il modulo turtle)
import turtle
def cy(r):
turtle.setup(400,400)
turtle.penup()
turtle.hideturtle()
turtle.speed(0)
for i in range(1000):
x,y=random.randint(-200,200),random.randint(-200,200)
if (x*x+y*y)**0.5 < r:
color="red"
else:
color="blue"
turtle.goto(x,y)
turtle.dot(5,color)
if __name__=="__main__":
r=float(input("scrivi un numero (consigliato da 100 a 200): "))
print("guarda il risultato della funzione misteriosa")
cy(r)
turtle.exitonclick()
6
(richiede il modulo turtle)
import turtle
def poly(n):
for i in range(n):
turtle.forward(50)
turtle.left(360/n)
if __name__=="__main__":
n=int(input("dammi un intero (consigliato da 3 a 12): "))
poly(n)
turtle.exitonclick()
7
Questo e' contorto. Se vi piace... iniziate a preoccuparvi: state diventando informatici ;-)
f="f={0}{1}{0};print(f.format(chr(34),f))";print(f.format(chr(34),f))
NB: non e' necessario capire questo programma, e' solo per chi si vuole cimentare in una sfida...
8
def pf(n):
f=[]
for i in range(2,n+1):
while n % i == 0:
f.append(i)
n //= i
if n == 1:
break
return f
def fgcd(a,b):
def rgcd(fa,fb):
if fa and fb:
if fa[0]==fb[0]:
return fa[:1]+rgcd(fa[1:],fb[1:])
elif fa[0]<fb[0]:
return rgcd(fa[1:],fb)
else:
return rgcd(fa,fb[1:])
else:
return []
return rgcd(pf(a),pf(b))
def flcm(a,b):
def rlcm(fa,fb):
if fa and fb:
if fa[0]==fb[0]:
return fa[:1]+rlcm(fa[1:],fb[1:])
elif fa[0]<fb[0]:
return fa[:1]+rlcm(fa[1:],fb)
else:
return fa[:1]+rlcm(fa,fb[1:])
else:
return fa if fa else fb
return rlcm(pf(a),pf(b))
def mul(l):
rv=1
for el in l:
rv *= el
return rv
def gcd(x,y):
return mul(fgcd(x,y))
def lcm(x,y):
return mul(flcm(x,y))
if __name__=="__main__":
a,b=input("Inserisci due numeri (es: 48 36): ").split()
a,b=int(a),int(b)
print("pf({})={}".format(a,pf(a)))
print("pf({})={}".format(b,pf(b)))
print("fgcd({},{})={}".format(a,b,fgcd(a,b)))
print("flcm({},{})={}".format(a,b,flcm(a,b)))
print("gcd({},{})={}".format(a,b,gcd(a,b)))
print("lcm({},{})={}".format(a,b,lcm(a,b)))
9
def div(n):
return {x for x in range(1,n+1) if n % x == 0}
#alternativa:
#def div(n):
# d=set()
# for x in range(1,n+1):
# if n % x == 0: d.add(x)
# return d
def gcd(a,b):
return max(div(a) & div(b))
def mul(n,limit):
return {x*n for x in range(1,limit//n + 1)}
#alternativa
#def mul(n,limit):
# d=set()
# for x in range(1,limit//n + 1):
# d.add(x*n)
# return d
def lcm(a,b):
return min(mul(a,a*b) & mul(b,a*b))
if __name__=="__main__":
a,b=input("Inserisci due numeri (es: 48 36): ").split()
a,b=int(a),int(b)
print("div({})={}".format(a,div(a)))
print("div({})={}".format(b,div(b)))
print("mul({},{})={}".format(a,a*b,mul(a,a*b)))
print("mul({},{})={}".format(b,a*b,mul(b,a*b)))
print("gcd({},{})={}".format(a,b,gcd(a,b)))
print("lcm({},{})={}".format(a,b,lcm(a,b)))
10
def sdiv(n):
return {x for x in range(2,n) if n % x == 0}
#alternativa:
#def sdiv(n):
# d=set()
# for x in range(2,n):
# if n % x == 0: d.add(x)
# return d
def pr(n):
return not sdiv(n)
def pdiv(n):
return {x for x in sdiv(n) if pr(x)}
#alternativa:
#def pdiv(n):
# d=set()
# for x in sdiv(n):
# if pr(x): d.add(x)
# return d
def gcd(a,b):
csdiv=pdiv(a) & pdiv(b)
r=1
for x in csdiv:
while a % (r*x) == 0 and b % (r*x) == 0:
r *= x
return r
def lcm(a,b):
return a * b // gcd(a,b)
if __name__=="__main__":
a,b=input("Inserisci due numeri (es: 48 36): ").split()
a,b=int(a),int(b)
print("pdiv({})={}".format(a,pdiv(a)))
print("pdiv({})={}".format(b,pdiv(b)))
print("gcd({},{})={}".format(a,b,gcd(a,b)))
print("lcm({},{})={}".format(a,b,lcm(a,b)))
11
def tartline(l):
l[:0]=[1]
for i in range(1,len(l)-1):
l[i] += l[i+1]
l=[]
for i in range(12):
tartline(l)
print("{:^60}".format(l))
12
def sdiv(n):
return {x for x in range(2,n) if n % x == 0}
#alternativa:
#def sdiv(n):
# d=set()
# for x in range(2,n):
# if n % x == 0: d.add(x)
# return d
def pr(n):
return not sdiv(n)
N=int(input("dammi il numero massimo (es 100): "))
print("ecco i numeri ***** fino a",N,":",[n for n in range(1,N+1) if pr(n)])
13
vf=[("Nella vecchia fattoria","Quante bestie ha zio Tobia","C'e' la capra","capra","ca"),
("Attaccato a un carrettino","C'è un quadrupede piccino","L'asinel","nel","nè"),
("Tra le casse e i ferri rotti", "Dove i topi son grassotti","C'è un bel gatto","gatto","ga"),
("Tanto grasso e tanto grosso", "Sempre sporco a più non posso", "C'è il maiale","iale","ia"),
("Poi sull'argine del fosso", "Alle prese con un osso", "C'è un bel cane","cane","ca"),
("Nella stalla silenziosa", "Dopo aver mangiato a iosa", "Dorme il bue","bue","bu")]
refrain="ia ia o"
def recverse(m,n):
v1,v2,an1,an2,an3=vf[m]
if n==m:
print(v1,refrain)
print(v2,refrain)
else:
recverse(m+1,n)
print(an1,an2,an3,an3,an2)
for i in range(len(vf)):
recverse(0,i)
print(vf[0][0],refrain)
print()
14
import turtle
def hser(size, level):
if level==0:
turtle.forward(size)
else:
hser(size,level-1)
turtle.left(45)
turtle.forward(size * 2**0.5)
turtle.left(45)
hser(size,level-1)
turtle.right(90)
turtle.forward(size)
turtle.right(90)
hser(size,level-1)
turtle.left(45)
turtle.forward(size * 2**0.5)
turtle.left(45)
hser(size,level-1)
def ser(size, level):
turtle.penup()
pos=(2**(level+2)-3) * size // 2 #posizione iniziale
turtle.setpos(-pos,pos)
turtle.pendown()
hser(size,level)
turtle.right(90)
hser(size,level)
turtle.right(90)
hser(size,level)
turtle.right(90)
hser(size,level)
turtle.right(90)
turtle.speed(0)
turtle.hideturtle()
ser(2,1)
ser(2,2)
ser(2,3)
ser(2,4)
turtle.exitonclick()
15
import turtle
import colorsys
import sys
def arrowstep(level, length, angle):
if level:
arrowstep(level-1, length/2, -angle)
turtle.left(angle)
arrowstep(level-1, length/2, angle)
turtle.left(angle)
arrowstep(level-1, length/2, -angle)
else:
turtle.forward(length)
def arrow(level, length):
if level & 1:
turtle.left(60)
arrowstep(level, length, -60)
else:
arrowstep(level, length, -60)
turtle.speed(0)
turtle.hideturtle()
turtle.colormode(1)
nmax=6
width=256
xmin= -width//2
ymin= -width*(3**0.5)//4
for n in range(nmax):
turtle.penup()
turtle.setposition(xmin,ymin)
turtle.setheading(0)
turtle.pencolor(colorsys.hls_to_rgb(1.0*n/6,0.5,1))
turtle.pendown()
arrow(n,256)
turtle.exitonclick()
16
def av(l):
return sum(l)/len(l)
def rg(l):
return max(l)-min(l)
def md(l):
lx=len(l)
ls=sorted(l)
if lx%2:
return ls[lx//2]
else:
return (ls[lx//2-1]+ls[lx//2])/2
if __name__=="__main__":
l=input("dammi una lista di numeri separati da virgole (es: 1,2,3,4.4): ")
l=[float(x) for x in l.split(',')]
print("i valori trovati dalle tre funzioni sono: {:.4f} {:.4f} {:.4f}".format(av(l),rg(l),md(l)))
17
import turtle
import sys
rows,cols=4,4
buttonsize=50
topdisplay=2*buttonsize
stack=[0]
fresh=True
def num(x):
global fresh,stack
if fresh:
stack[:0]=[x]
fresh=False
else:
stack[0]=stack[0]*10+x
enter,add,sub,mul,div=0,int.__add__,int.__sub__,int.__mul__,int.__floordiv__
def op(x):
global fresh,stack
if x!=enter and len(stack)>1:
stack=[x(stack[1],stack[0])]+stack[2:]
fresh=True
def off(x):
sys.exit(0)
buttons={
(0,0):('0',num,0), (1,0):('1',num,1), (1,1):('2',num,2), (1,2):('3',num,3), (2,0):('4',num,4),
(2,1):('5',num,5), (2,2):('6',num,6), (3,0):('7',num,7), (3,1):('8',num,8), (3,2):('9',num,9),
(3,3):('+',op,add), (2,3):('-',op,sub), (1,3):('*',op,mul), (0,3):('/',op,div),
(0,2):('ent',op,enter), (0,1):('off',off,0)}
def click(x,y):
col=x//buttonsize
row=y//buttonsize
if (row,col) in buttons:
label,op,val=buttons[row,col]
op(val)
drawcalc()
def drawcalc():
def drawbutton(col,row,label):
turtle.setpos(row*buttonsize,col*buttonsize)
turtle.pendown()
for _ in range(4):
turtle.forward(buttonsize)
turtle.left(90)
turtle.penup()
turtle.setpos(row*buttonsize+buttonsize//2,col*buttonsize+buttonsize//2)
turtle.write(label,align="center")
turtle.clear()
turtle.penup()
for row,col in buttons:
drawbutton(row,col,buttons[row,col][0])
turtle.setpos(row*buttonsize*(rows-1),col*buttonsize*(cols+1))
turtle.write(str(stack[0]),align="right")
turtle.update()
turtle.screensize(cols*buttonsize+1, rows*buttonsize+topdisplay+1)
turtle.setup(cols*buttonsize+1, rows*buttonsize+topdisplay+1)
turtle.setworldcoordinates(0,0,cols*buttonsize, rows*buttonsize+topdisplay)
turtle.hideturtle()
turtle.speed(10)
turtle.tracer(0)
drawcalc()
turtle.onscreenclick(click)
turtle.listen()
turtle.mainloop()
18
import turtle
import colorsys
import time
N=6
frompin=list(range(N,0,-1))
auxpin=[]
topin=[]
def rectangle(size, level, pin):
turtle.penup()
turtle.setpos(2*N*10*pin,level*10)
turtle.setheading(0)
turtle.pendown()
turtle.fillcolor(colorsys.hls_to_rgb(1.0*(size-1)/N,0.5,1))
turtle.begin_fill()
turtle.forward(size*10)
turtle.left(90)
turtle.forward(10)
turtle.left(90)
turtle.forward(size*20)
turtle.left(90)
turtle.forward(10)
turtle.left(90)
turtle.forward(size*10)
turtle.end_fill()
def showhanoi():
turtle.clear()
lf,la,lt=map(len,(frompin,auxpin,topin))
for i in range(lf):
rectangle(frompin[i], i, -1)
for i in range(la):
rectangle(auxpin[i], i, 0)
for i in range(lt):
rectangle(topin[i], i, 1)
turtle.update()
time.sleep(0.2)
def hanoi(n,f,a,t):
if n==1:
t.append(f.pop())
showhanoi()
else:
hanoi(n-1,f,t,a)
hanoi(1,f,a,t)
hanoi(n-1,a,f,t)
turtle.hideturtle()
turtle.speed(10)
turtle.tracer(0)
showhanoi()
hanoi(N,frompin,auxpin,topin)
turtle.exitonclick()