py3: towards docbuild, more details

[chapoton]

New commits:

​6685b17

py3: more details, towards docbuild

[jdemeyer]

What's wrong with

P = sum([arrow2d((0,0), (cos(x*0.1),sin(x*0.1)), hue=x/(20*pi)) for x in range(0,20*pi+1)])

[chapoton]

[dochtml] [plotting ] During handling of the above exception, another exception occurred:
[dochtml] [plotting ] Traceback (most recent call last):
[dochtml] [plotting ] File "/home/chapoton/sage3/local/lib/python3.6/site-packages/matplotlib/sphinxext/plot_directive.py", line 525, in run_code
[dochtml] [plotting ] six.exec_(code, ns)
[dochtml] [plotting ] File "<string>", line 1, in <module>
[dochtml] [plotting ] File "sage/symbolic/expression.pyx", line 5721, in sage.symbolic.expression.Expression.__index__ (build/cythonized/sage/symbolic/expression.cpp:35714)
[dochtml] [plotting ] File "sage/symbolic/expression.pyx", line 1073, in sage.symbolic.expression.Expression._integer_ (build/cythonized/sage/symbolic/expression.cpp:9100)
[dochtml] [plotting ] TypeError: unable to convert 20*pi + 1 to an integer

[jdemeyer]

Well, that's a genuine problem. Why shouldn't we no longer be allowed to use symbolic expressions in plots?

[jdemeyer]

I reverted that because it tries to fix the doctest instead of the bug.

The other change gets positive review.

---

New commits:

​a9abcc8

py3: more details, towards docbuild

[chapoton]

Jeroen, see your own comment here: ​https://trac.sagemath.org/ticket/24758#comment:2

[chapoton]

And the range behaviour itself is not working with python3. I do not think we should change that.

sage: list(range(20*pi+3))
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
/home/chapoton/sage3/local/lib/python3.6/site-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression._integer_ (build/cythonized/sage/symbolic/expression.cpp:9051)()

/home/chapoton/sage3/local/lib/python3.6/site-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression.pyobject (build/cythonized/sage/symbolic/expression.cpp:6090)()

TypeError: self must be a numeric expression

During handling of the above exception, another exception occurred:

TypeError                                 Traceback (most recent call last)
<ipython-input-1-3c6188e69b81> in <module>()
----> 1 list(range(Integer(20)*pi+Integer(3)))

/home/chapoton/sage3/local/lib/python3.6/site-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression.__index__ (build/cythonized/sage/symbolic/expression.cpp:35714)()

/home/chapoton/sage3/local/lib/python3.6/site-packages/sage/symbolic/expression.pyx in sage.symbolic.expression.Expression._integer_ (build/cythonized/sage/symbolic/expression.cpp:9100)()

TypeError: unable to convert 20*pi + 3 to an integer

[chapoton]

Jeroen, would you accept this change that you refused here (in another ticket):

-        P = sum([arrow2d((0,0), (cos(x*0.1),sin(x*0.1)), hue=x/(20*pi)) for x in range(0,20*pi+1)])
+        P = sum([arrow2d((0,0), (cos(x*0.1),sin(x*0.1)), hue=x/(20*pi)) for x in range(floor(20*pi)+1)])

It seems to me that there is no issue in sage, only the fact that python3 is more strict on what it accepts inside range.

[jdemeyer]

Replying to chapoton:

Jeroen, would you accept this change that you refused here (in another ticket):

-        P = sum([arrow2d((0,0), (cos(x*0.1),sin(x*0.1)), hue=x/(20*pi)) for x in range(0,20*pi+1)])
+        P = sum([arrow2d((0,0), (cos(x*0.1),sin(x*0.1)), hue=x/(20*pi)) for x in range(floor(20*pi)+1)])

That's not precisely the change that I rejected. You changed 20*pi by 63 originally in multiple places.

Anyway, let me figure out exactly what range() accepts on Python 2 and Python 3 and then I'll comment back.

[jdemeyer]

Replying to chapoton:

It seems to me that there is no issue in sage, only the fact that python3 is more strict on what it accepts inside range.

I agree. Python 2 essentially replaces range(foo) by range(int(foo)). Python 3 requires an integer as argument to range().

[chapoton]

Ok. I have made the ticket in #25578