mod, modulo and % under 2.4 and 2.5

[W. eWatson]

About a year ago, I wrote a program that used mod() for modulo under
2.5. Apparently, % is also acceptable, but the program works quite well.
I turned the program over to someone who is using 2.4, and apparently
2.4 knows nothing about mod(). Out of curiosity, what library is
mod(a,b)(two args) in? It doesn't seem to be in numpy. It seems to be
built-in. If so, why isn't it both 2.4 and 2.5?

 

[Steven D'Aprano]

About a year ago, I wrote a program that used mod() for modulo under
2.5. Apparently, % is also acceptable, but the program works quite well.
I turned the program over to someone who is using 2.4, and apparently
2.4 knows nothing about mod(). Out of curiosity, what library is
mod(a,b)(two args) in? It doesn't seem to be in numpy. It seems to be
built-in.

No it doesn't.

[steve@sylar ~]$ python2.5
Python 2.5 (r25:51908, Nov 6 2007, 16:54:01)
[GCC 4.1.2 20070925 (Red Hat 4.1.2-27)] on linux2
Type "help", "copyright", "credits" or "license" for more information.Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'mod' is not defined

 

[Jan Kaliszewski]

About a year ago, I wrote a program that used mod() for modulo under
2.5. Apparently, % is also acceptable, but the program works quite well.
I turned the program over to someone who is using 2.4, and apparently
2.4 knows nothing about mod(). Out of curiosity, what library is
mod(a,b)(two args) in? It doesn't seem to be in numpy. It seems to be
built-in. If so, why isn't it both 2.4 and 2.5?

???

There is no builtin mod() function at all, but there are (in Py 2.4, 2.5,
2.6, 3.0 and 3.1):
* builtin '%' and '%=' operators
* builtin divmod()
* in 'operator' module: mod() or __mod__() [the same] -- equivalents of
'%' operator
* in 'math' module: fmod() function

Additionaly, since Py 2.5 in 'operator' module there is imod() and
__imod__() [the same] -- equivalents of '%=' operator.

Cheers,
*j

 

[W. eWatson]

About a year ago, I wrote a program that used mod() for modulo under
2.5. Apparently, % is also acceptable, but the program works quite well.
I turned the program over to someone who is using 2.4, and apparently
2.4 knows nothing about mod(). Out of curiosity, what library is
mod(a,b)(two args) in? It doesn't seem to be in numpy. It seems to be
built-in.

No it doesn't.

[steve@sylar ~]$ python2.5
Python 2.5 (r25:51908, Nov 6 2007, 16:54:01)
[GCC 4.1.2 20070925 (Red Hat 4.1.2-27)] on linux2
Type "help", "copyright", "credits" or "license" for more information.Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'mod' is not defined

So where is it? Here are the choices.
import sys, os, glob
import string
from numpy import *
from datetime import datetime, timedelta
import time

In the 2.4 version, I change nmnpy to Numeric

 

[MRAB]

About a year ago, I wrote a program that used mod() for modulo under
2.5. Apparently, % is also acceptable, but the program works quite
well. I turned the program over to someone who is using 2.4, and
apparently 2.4 knows nothing about mod(). Out of curiosity, what
library is mod(a,b)(two args) in? It doesn't seem to be in numpy. It
seems to be built-in. If so, why isn't it both 2.4 and 2.5?

mod() not is a built-in.

It is, however, in the 'operator' module, and also as __mod__() in that
same module. Both are equivalent to '%'.

It has been there since at least Python v2.0.

As for why something might not be in an earlier version, well, that
would be because it hadn't been added yet!

 

[MRAB]

About a year ago, I wrote a program that used mod() for modulo under
2.5. Apparently, % is also acceptable, but the program works quite well.
I turned the program over to someone who is using 2.4, and apparently
2.4 knows nothing about mod(). Out of curiosity, what library is
mod(a,b)(two args) in? It doesn't seem to be in numpy. It seems to be
built-in.

No it doesn't.

[steve@sylar ~]$ python2.5
Python 2.5 (r25:51908, Nov 6 2007, 16:54:01)
[GCC 4.1.2 20070925 (Red Hat 4.1.2-27)] on linux2
Type "help", "copyright", "credits" or "license" for more information.

mod

Traceback (most recent call last):
File "<stdin>", line 1, in <module>
NameError: name 'mod' is not defined

If you think it's built-in then you've probably imported it from a
module using the form "from some_module import *".

So where is it? Here are the choices.
import sys, os, glob
import string
from numpy import *

Aha, there you are!

from datetime import datetime, timedelta
import time

In the 2.4 version, I change nmnpy to Numeric

'numpy' does contain a function called 'mod'.
<ufunc 'remainder'>

Does 'Numeric'?

 

[Steven D'Aprano]

If you use ‘from foo import *’ you forfeit any way of saying where a
name in your code gets bound.

Not quite:
'math'

But this only works with functions and classes, not arbitrary objects:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'float' object has no attribute '__module__'

Hence, don't do that.

Avoiding "from module import *" is generally excellent advice. There's
one or two exceptions, but if you have to ask what they are, you don't
need to know *wink*

 

[W. eWatson]

If you use ‘from foo import *’ you forfeit any way of saying where a
name in your code gets bound.

Hence, don't do that.

Good idea!