Generators can only yield ints?

[defn noob]

def letters():
a = xrange(ord('a'), ord('z')+1)
B = xrange(ord('A'), ord('Z')+1)
while True:
yield chr(a)
yield chr(B)


Traceback (most recent call last):
File "<pyshell#225>", line 1, in <module>
l.next()
File "<pyshell#223>", line 5, in letters
yield chr(a)
TypeError: an integer is required

Any way to get around this?

 

[bearophileHUGS]

defn noob:

Any way to get around this?

Your code is wrong, this is one of the correct versions:

from itertools import izip

def letters():
lower = xrange(ord('a'), ord('z')+1)
upper = xrange(ord('A'), ord('Z')+1)
for lc, uc in izip(lower, upper):
yield chr(lc)
yield chr(uc)

print list(letters())

There are other ways to do the same thing.

Bye,
bearophile

 

[Medardo Rodriguez (Merchise Group)]

def letters():
a = xrange(ord('a'), ord('z')+1)
B = xrange(ord('A'), ord('Z')+1)
while True:
yield chr(a)
yield chr(B)


TypeError: an integer is required

No. The problem is that "chr function" receives "int"
"a" and "B" are generators of "int" items.

What exactly you intent with that code?

Maybe:
#<code>
def letters():
for i in xrange(ord('a'), ord('z')+1):
yield chr(i)
for i in xrange(ord('A'), ord('Z')+1):
yield chr(i)

for letter in letters():
print letter
#</code>

Regards

 

[Steven D'Aprano]

def letters():
a = xrange(ord('a'), ord('z')+1)
B = xrange(ord('A'), ord('Z')+1)
while True:
yield chr(a)
yield chr(B)



Traceback (most recent call last):
File "<pyshell#225>", line 1, in <module>
l.next()
File "<pyshell#223>", line 5, in letters
yield chr(a)
TypeError: an integer is required

Any way to get around this?

Yes, write code that isn't buggy

Generators can return anything you want. Your problem is that you're
passing an xrange object to chr() instead of an int. Try this:

def letters():
a = xrange(ord('a'), ord('z')+1)
B = xrange(ord('A'), ord('Z')+1)
for t in zip(a, B):
yield chr(t[0])
yield chr(t[1])

But (arguably) a better way is:

def letters():
from string import ascii_letters as letters
for a,b in zip(letters[0:26], letters[26:]):
yield a
yield b


Note that it is important to use ascii_letters rather than letters,
because in some locales the number of uppercase and lowercase letters
differ.

 

[Lie]

def letters():
        a = xrange(ord('a'), ord('z')+1)
        B = xrange(ord('A'), ord('Z')+1)
        while True:
                yield chr(a)
                yield chr(B)


Traceback (most recent call last):
  File "<pyshell#225>", line 1, in <module>
    l.next()
  File "<pyshell#223>", line 5, in letters
    yield chr(a)
TypeError: an integer is required



Any way to get around this?

The most direct translation on what you've done, with corrections, is
either this:

def letters():
a = xrange(ord('a'), ord('z') + 1)
B = xrange(ord('A'), ord('Z') + 1)
while True:
yield a
yield B
xrange(97, 123)

or this:

def letters():
a = xrange(ord('a'), ord('z') + 1)
B = xrange(ord('A'), ord('Z') + 1)
while True:
yield [chr(char) for char in a]
yield [chr(char) for char in B]
['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z']

but my psychic ability guessed that you actually wanted this instead:


def letters():
a = xrange(ord('a'), ord('z') + 1)
B = xrange(ord('A'), ord('Z') + 1)
a = [chr(char) for char in a]
B = [chr(char) for char in B]
index = 0
while index < 26:
yield a[index]
yield B[index]
index += 1
'a'

or possibly in a more pythonic style, using for:

def letters():
a = xrange(ord('a'), ord('z') + 1)
B = xrange(ord('A'), ord('Z') + 1)
for lower, upper in zip(a, B):
yield chr(lower)
yield chr(upper)
'a'

paralelly, my psychic ability also tells me that you might prefer this
instead:

def letters():
a = xrange(ord('a'), ord('z') + 1)
B = xrange(ord('A'), ord('Z') + 1)
for lower, upper in zip(a, B):
yield chr(lower), chr(upper)
('a', 'A')