syntax error in sum(). Please explicate.

[Michael Press]

I have not written python codes nor run any. I saw this
code posted and decided to try it. It fails. I read the
tutorial and the entry for the built in function sum,
but still do not see the problem. The code was cut and
paste. Please help. Thanks.

_______________ __________BEGIN _CODE__________ _______________
#!/usr/bin/python

ps = [none, 2,3,5,7,11,13,1 7,19,23,29]

def phi(x, a):
return x - sum(phi(x // ps[i+1], i) for i in range(a))

def pi(n):
from math import sqrt
if n <= 1:
return 0
a = pi(int(sqrt(n)) )
return phi(n, a) + a - 1
_______________ ___________END_ CODE___________ _______________

Here is the result of running it:

File "/Users/mdp/source/prime_counter_p ython", line 6
return x - sum(phi(x // ps[i+1], i) for i in range(a))
^
SyntaxError: invalid syntax

Here are some lines from python -v:

Python 2.3 (#1, Sep 13 2003, 00:49:11)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1495)] on darwin
Type "help", "copyright" , "credits" or "license" for more information

--
Michael Press

[tom]

Re: syntax error in sum(). Please explicate.

Michael Press wrote:

I have not written python codes nor run any. I saw this
code posted and decided to try it. It fails. I read the
tutorial and the entry for the built in function sum,
but still do not see the problem. The code was cut and
paste. Please help. Thanks.
>
_______________ __________BEGIN _CODE__________ _______________
#!/usr/bin/python
>
ps = [none, 2,3,5,7,11,13,1 7,19,23,29]
>
>

None has a capital N ^

def phi(x, a):
return x - sum(phi(x // ps[i+1], i) for i in range(a))
>
def pi(n):
from math import sqrt
if n <= 1:
return 0
a = pi(int(sqrt(n)) )
return phi(n, a) + a - 1
_______________ ___________END_ CODE___________ _______________
>
Here is the result of running it:
>
File "/Users/mdp/source/prime_counter_p ython", line 6
return x - sum(phi(x // ps[i+1], i) for i in range(a))
^
SyntaxError: invalid syntax
>
>

can you paste the complete code? I'm not sure why that's a syntax error
there. with a bit of fudging it seems to run in the interpreter ok...

Here are some lines from python -v:
>
Python 2.3 (#1, Sep 13 2003, 00:49:11)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1495)] on darwin
Type "help", "copyright" , "credits" or "license" for more information
>
>

[Matt Moriarity]

Re: syntax error in sum(). Please explicate.

try surrounding your sum argument in brackets:

sum([phi(x // ps[i+1], i) for i in range(a)])

instead of:

sum(phi(x // ps[i+1], i) for i in range(a))

On Nov 18, 5:23 pm, Michael Press <j...@abc.netwr ote:

I have not written python codes nor run any. I saw this
code posted and decided to try it. It fails. I read the
tutorial and the entry for the built in function sum,
but still do not see the problem. The code was cut and
paste. Please help. Thanks.
>
_______________ __________BEGIN _CODE__________ _______________
#!/usr/bin/python
>
ps = [none, 2,3,5,7,11,13,1 7,19,23,29]
>
def phi(x, a):
return x - sum(phi(x // ps[i+1], i) for i in range(a))
>
def pi(n):
from math import sqrt
if n <= 1:
return 0
a = pi(int(sqrt(n)) )
return phi(n, a) + a - 1
_______________ ___________END_ CODE___________ _______________
>
Here is the result of running it:
>
File "/Users/mdp/source/prime_counter_p ython", line 6
return x - sum(phi(x // ps[i+1], i) for i in range(a))
^
SyntaxError: invalid syntax
>
Here are some lines from python -v:
>
Python 2.3 (#1, Sep 13 2003, 00:49:11)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1495)] on darwin
Type "help", "copyright" , "credits" or "license" for more information
>
--
Michael Press

[Paul Rubin]

Re: syntax error in sum(). Please explicate.

Michael Press <jack@abc.netwr ites:

File "/Users/mdp/source/prime_counter_p ython", line 6
return x - sum(phi(x // ps[i+1], i) for i in range(a))
^
SyntaxError: invalid syntax
>
Here are some lines from python -v:
>
Python 2.3 (#1, Sep 13 2003, 00:49:11)

Generator comprehensions like you used weren't introduced til
Python 2.4, so 2.3 will raise a syntax error like you got.

[John Machin]

Re: syntax error in sum(). Please explicate.


Michael Press wrote:

I have not written python codes nor run any. I saw this
code posted and decided to try it. It fails. I read the
tutorial and the entry for the built in function sum,
but still do not see the problem. The code was cut and
paste.

I doubt it -- "none" should be "None"

Please help. Thanks.

>
_______________ __________BEGIN _CODE__________ _______________
#!/usr/bin/python
>
ps = [none, 2,3,5,7,11,13,1 7,19,23,29]
>
def phi(x, a):
return x - sum(phi(x // ps[i+1], i) for i in range(a))
>
def pi(n):
from math import sqrt
if n <= 1:
return 0
a = pi(int(sqrt(n)) )
return phi(n, a) + a - 1
_______________ ___________END_ CODE___________ _______________
>
Here is the result of running it:
>
File "/Users/mdp/source/prime_counter_p ython", line 6
return x - sum(phi(x // ps[i+1], i) for i in range(a))
^
SyntaxError: invalid syntax
>
Here are some lines from python -v:
>
Python 2.3 (#1, Sep 13 2003, 00:49:11)
[GCC 3.3 20030304 (Apple Computer, Inc. build 1495)] on darwin
Type "help", "copyright" , "credits" or "license" for more information

New syntax. Python 2.3 is *two* versions behind the current production
version. Either (a) run it on Python 2.4 or 2.5 or (b) enclose the
argument to sum in square brackets i.e.

sum([blah blah blah]) instead of sum(blah blah blah)

Cheers,
John

[Michael Press]

Re: syntax error in sum(). Please explicate.

In article
<1163889196.135 008.126970@h54g 2000cwb.googleg roups.com>
,
"Matt Moriarity" <matt.moriarity @gmail.comwrote :

try surrounding your sum argument in brackets:
>
sum([phi(x // ps[i+1], i) for i in range(a)])
>
instead of:
>
sum(phi(x // ps[i+1], i) for i in range(a))

Thank you. That makes it work.

--
Michael Press

[Tim Peters]

Re: syntax error in sum(). Please explicate.

[Matt Moriarity]

>try surrounding your sum argument in brackets:
>>
>sum([phi(x // ps[i+1], i) for i in range(a)])
>>
>instead of:
>>
>sum(phi(x // ps[i+1], i) for i in range(a))

[Michael Press]

Thank you. That makes it work.

But is a wrong solution ;-) As others have suggested, it's almost
certainly the case that you were using a too-old version of Python.
2.5 is current, and 2.4.4 (the current bugfix release in the 2.4 line)
would also work. You must have been using a version before 2.4, and
if you're just starting with Python, it's a Bad Idea to artificially
burden yourself with an old version where current examples can't work
;-)

[Bjoern Schliessmann]

Re: syntax error in sum(). Please explicate.

Paul Rubin wrote:

Generator comprehensions

Are generator comprehensions and generator expressions the same?

Regards,


Björn

--
BOFH excuse #35:

working as designed

[Fredrik Lundh]

Re: syntax error in sum(). Please explicate.

Bjoern Schliessmann wrote:

Are generator comprehensions and generator expressions the same?

the documentation uses the word "expression ", not comprehension.

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