问题
I need to make a program that asks for the amount of Fibonacci numbers printed and then prints them like 0, 1, 1, 2... but I can\'t get it to work. My code looks the following:
a = int(raw_input(\'Give amount: \'))
def fib():
a, b = 0, 1
while 1:
yield a
a, b = b, a + b
a = fib()
a.next()
0
for i in range(a):
print a.next(),
回答1:
I would use this method:
Python 2
a = int(raw_input('Give amount: '))
def fib(n):
a, b = 0, 1
for _ in xrange(n):
yield a
a, b = b, a + b
print list(fib(a))
Python 3
a = int(input('Give amount: '))
def fib(n):
a, b = 0, 1
for _ in range(n):
yield a
a, b = b, a + b
print(list(fib(a)))
回答2:
You are giving a too many meanings:
a = int(raw_input('Give amount: '))
vs.
a = fib()
You won't run into the problem (as often) if you give your variables more descriptive names (3 different uses of the name a in 10 lines of code!):
amount = int(raw_input('Give amount: '))
and change range(a) to range(amount).
回答3:
Since you are writing a generator, why not use two yields, to save doing the extra shuffle?
import itertools as it
num_iterations = int(raw_input('How many? '))
def fib():
a,b = 0,1
while True:
yield a
b = a+b
yield b
a = a+b
for x in it.islice(fib(), num_iterations):
print x
.....
回答4:
Your a is a global name so-to-say.
a = int(raw_input('Give amount: '))
Whenever Python sees an a, it thinks you are talking about the above one. Calling it something else (elsewhere or here) should help.
回答5:
Also you can use enumerate infinite generator:
for i,f in enumerate(fib()):
print i, f
if i>=n: break
回答6:
Also you can try the closed form solution (no guarantees for very large values of n due to rounding/overflow errors):
root5 = pow(5, 0.5)
ratio = (1 + root5)/2
def fib(n):
return int((pow(ratio, n) - pow(1 - ratio, n))/root5)
回答7:
You had the right idea and a very elegant solution, all you need to do fix is your swapping and adding statement of a and b. Your yield statement should go after your swap as well
a, b = b, a + b #### should be a,b = a+b,a #####
`###yield a`
回答8:
def fibonacci(n):
fn = [0, 1,]
for i in range(2, n):
fn.append(fn[i-1] + fn[i-2])
return fn
回答9:
Simple way to print Fibonacci series till n number
def Fib(n):
i=a=0
b=1
while i<n:
print (a)
i=i+1
c=a+b
a=b
b=c
Fib(input("Please Enter the number to get fibonacci series of the Number : "))
回答10:
To get the fibonacci numbers till any number (100 in this case) with generator, you can do this.
def getFibonacci():
a, b = 0, 1
while True:
yield b
b = a + b
a = b - a
for num in getFibonacci():
if num > 100:
break
print(num)
回答11:
Python is a dynamically typed language. the type of a variable is determined at runtime and it can vary as the execution is in progress. Here at first, you have declared a to hold an integer type and later you have assigned a function to it and so its type now became a function.
you are trying to apply 'a' as an argument to range() function which expects an int arg but you have in effect provided a function variable as argument.
the corrected code should be
a = int(raw_input('Give amount: '))
def fib():
a, b = 0, 1
while 1:
yield a
a, b = b, a + b
b = fib()
b.next()
for i in range(a):
print b.next(),
this will work
回答12:
I've build this a while ago:
a = int(raw_input('Give amount: '))
fab = [0, 1, 1]
def fab_gen():
while True:
fab.append(fab[-1] + fab[-2])
yield fab[-4]
fg = fab_gen()
for i in range(a): print(fg.next())
No that fab will grow over time, so it isn't a perfect solution.
回答13:
It looks like you are using the a twice. Try changing that to a different variable name.
The following seems to be working great for me.
def fib():
a, b = 0, 1
while True:
yield a
a, b = b, a+b
f = fib()
for x in range(100):
print(f.next())
回答14:
i like this version:
array = [0,1]
for i in range(20):
x = array[0]+array[1]
print(x)
array[0] = array[1]
array[1] = x
回答15:
def genFibanocciSeries():
a=0
b=1
for x in range(1,10):
yield a
a,b = b, a+b
for fib_series in genFibanocciSeries():
print(fib_series)
回答16:
Below are two solution for fiboncci generation:
def fib_generator(num):
'''
this will works as generator function and take yield into account.
'''
assert num > 0
a, b = 1, 1
while num > 0:
yield a
a, b = b, a+b
num -= 1
times = int(input('Enter the number for fib generaton: '))
fib_gen = fib_generator(times)
while(times > 0):
print(next(fib_gen))
times = times - 1
def fib_series(num):
'''
it collects entires series and then print it.
'''
assert num > 0
series = []
a, b = 1, 1
while num > 0:
series.append(a)
a, b = b, a+b
num -= 1
print(series)
times = int(input('Enter the number for fib generaton: '))
fib_series(times)
来源：https://stackoverflow.com/questions/3953749/python-fibonacci-generator