[sage-support] Inconsistency between Sage and Python
I am plotting some graphs, but the plot becomes cluttered because of the long labels. The labels are result of a conversion from a Real number to a string. The problem here is that Sage is not consistent with Python, as shown in the example below. Python: multiplier = [1.0e0, 1.0e1, 1.0e2] multiplier [1.0, 10.0, 100.0] str(multiplier[-1]) '100.0' Sage: sage: multiplier = [1.0e0, 1.0e1, 1.0e2] sage: multiplier [1.00, 10.0, 100.] sage: str(multiplier[-1]) '100.' Is this a correct behavior of Sage? at least for me, the excess of trailing zeros is causing some trouble. -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
Re: [sage-support] Inconsistency between Sage and Python
Hi João,
If you want precise control on the output, you might use the python
formatting (see
https://docs.python.org/2/library/string.html#formatstrings)
sage: x = RR(pi)
sage: print x
3.14159265358979
sage: print {:.3}.format(x)
3.1
sage: print {:.5}.format(x)
3.141
But perhaps it is not an answer to your question, is it?
Vincent
2014-10-06 18:03 UTC+02:00, João Alberto joa...@gmail.com:
I am plotting some graphs, but the plot becomes cluttered because of
the long labels. The labels are result of a conversion from a Real
number to a string. The problem here is that Sage is not consistent
with Python, as shown in the example below.
Python:
multiplier = [1.0e0, 1.0e1, 1.0e2]
multiplier
[1.0, 10.0, 100.0]
str(multiplier[-1])
'100.0'
Sage:
sage: multiplier = [1.0e0, 1.0e1, 1.0e2]
sage: multiplier
[1.00, 10.0, 100.]
sage: str(multiplier[-1])
'100.'
Is this a correct behavior of Sage? at least for me, the excess of
trailing zeros is causing some trouble.
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[sage-support] Re: Inconsistency between Sage and Python
João Alberto Ferreira wrote: I am plotting some graphs, but the plot becomes cluttered because of the long labels. The labels are result of a conversion from a Real number to a string. The problem here is that Sage is not consistent with Python, as shown in the example below. Python: multiplier = [1.0e0, 1.0e1, 1.0e2] multiplier [1.0, 10.0, 100.0] str(multiplier[-1]) '100.0' Sage: sage: multiplier = [1.0e0, 1.0e1, 1.0e2] sage: multiplier [1.00, 10.0, 100.] sage: str(multiplier[-1]) '100.' Is this a correct behavior of Sage? at least for me, the excess of trailing zeros is causing some trouble. One option is to work with RDF: sage: multiplier = [1.0e0, 1.0e1, 1.0e2] sage: multiplier = [RDF(x) for x in multiplier] sage: multiplier [1.0, 10.0, 100.0] sage: str(multiplier[-1]) '100.0' -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
Re: [sage-support] Inconsistency between Sage and Python
On 2014-10-06 18:03, João Alberto wrote: Is this a correct behavior of Sage? It's a feature, not a bug. The reason is that the number of digits gives an idea about the precision of the number. Compare sage: RealField(20)(1) 1. sage: RealField(100)(1) 1. If both these would be printed as 1.0, you would lose this information about the precision. Python has a fixed precision of 53 bits and prints a minimal number of digits. -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
[sage-support] Unsafe directory at startup
Installed pre-compiled Sage-6.3.app on Mac OS X 10.9.5 At startup of Terminal Session, there is this ~$ /Applications/Sage-6.3.app/Contents/Resources/sage/sage; exit sys:1: RuntimeWarning: not adding directory '' to sys.path since everybody can write to it. Untrusted users could put files in this directory which might then be imported by your Python code. As a general precaution from similar exploits, you should not execute Python code from this directory any ideas how to fix this? -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
Re: [sage-support] Unsafe directory at startup
Hello, What do you mean by fix? This is not a bug. I see at least two possibilities: - how to manage the rights on your computer: this is done with the chmod command. See for example http://en.wikipedia.org/wiki/Chmod - force ipython to add the current directory to sys.path: you can do that inside the console with sage: import sys sage: import os sage: sys.path.append(os.getcwd()) If it is something else, please be precise in your question. Vincent 2014-10-06 20:34 UTC+02:00, robert berne...@sbcglobal.net: Installed pre-compiled Sage-6.3.app on Mac OS X 10.9.5 At startup of Terminal Session, there is this ~$ /Applications/Sage-6.3.app/Contents/Resources/sage/sage; exit sys:1: RuntimeWarning: not adding directory '' to sys.path since everybody can write to it. Untrusted users could put files in this directory which might then be imported by your Python code. As a general precaution from similar exploits, you should not execute Python code from this directory any ideas how to fix this? -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
[sage-support] Re: Inconsistency between Sage and Python
Thank you, Samuel. The conversion to RDF worked because it coerces the other types to RDF (I think). If I convert the multiplier values to RR, RLF or float, the conversion does not help anymore. On Monday, October 6, 2014 1:30:03 PM UTC-3, slelievre wrote: João Alberto Ferreira wrote: I am plotting some graphs, but the plot becomes cluttered because of the long labels. The labels are result of a conversion from a Real number to a string. The problem here is that Sage is not consistent with Python, as shown in the example below. Python: multiplier = [1.0e0, 1.0e1, 1.0e2] multiplier [1.0, 10.0, 100.0] str(multiplier[-1]) '100.0' Sage: sage: multiplier = [1.0e0, 1.0e1, 1.0e2] sage: multiplier [1.00, 10.0, 100.] sage: str(multiplier[-1]) '100.' Is this a correct behavior of Sage? at least for me, the excess of trailing zeros is causing some trouble. One option is to work with RDF: sage: multiplier = [1.0e0, 1.0e1, 1.0e2] sage: multiplier = [RDF(x) for x in multiplier] sage: multiplier [1.0, 10.0, 100.0] sage: str(multiplier[-1]) '100.0' -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
Re: [sage-support] Inconsistency between Sage and Python
Yes, I know Vincent, thank you, but this would complicate my code
unnecessarily.
I used Samuel idea. But I still think that the extra trailing zeros have no
reason to exist.
On Monday, October 6, 2014 1:08:23 PM UTC-3, vdelecroix wrote:
Hi João,
If you want precise control on the output, you might use the python
formatting (see
https://docs.python.org/2/library/string.html#formatstrings)
sage: x = RR(pi)
sage: print x
3.14159265358979
sage: print {:.3}.format(x)
3.1
sage: print {:.5}.format(x)
3.141
But perhaps it is not an answer to your question, is it?
Vincent
2014-10-06 18:03 UTC+02:00, João Alberto joa...@gmail.com javascript::
I am plotting some graphs, but the plot becomes cluttered because of
the long labels. The labels are result of a conversion from a Real
number to a string. The problem here is that Sage is not consistent
with Python, as shown in the example below.
Python:
multiplier = [1.0e0, 1.0e1, 1.0e2]
multiplier
[1.0, 10.0, 100.0]
str(multiplier[-1])
'100.0'
Sage:
sage: multiplier = [1.0e0, 1.0e1, 1.0e2]
sage: multiplier
[1.00, 10.0, 100.]
sage: str(multiplier[-1])
'100.'
Is this a correct behavior of Sage? at least for me, the excess of
trailing zeros is causing some trouble.
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Re: [sage-support] Re: Typo in provided documentation
Yes Vincent, that sounds much better,
Cheers,
Nishan
On Saturday, 4 October 2014 05:21:15 UTC-4, vdelecroix wrote:
Hello,
Is it better worded as follows?
The issue: plot(h(x), 0, 4) plots the line y=x−2, not the multi-line
function defined by h. The reason? In the command plot(h(x), 0, 4),
first h(x) is evaluated: this means plugging the symbolic variable x
into the function h. The inequality x 2 evaluates to ``False`` and
hence ``h(x)`` evaluates to ``x - 2`` as it can be seen with
{{{
sage: bool(x 2)
False
sage: h(x)
x - 2
}}}
I also find misleading to have a Python argument (the x in def
h(x):) and a symbolic variable (here x) having the same name. At
least it should be mentioned.
Vincent
2014-10-02 20:32 UTC+02:00, NahsiN nishan.s...@gmail.com javascript::
@slelievre I was just pointing out what I think is a typo.
@slelievre You are right, the clause after the statement clarifies the
situation. When a symbolic equation is evaluated, as in the definition
of
h,
if it is not obviously true, then it returns False. Thus h(x) evaluates
to
x-2, and this is the function that gets plotted But I still feel the
whole
thing can be worded slightly better and more concisely. The if clause is
evaluated anyway when one calls h(x) so there is no point in saying x2
is
evaluated.
On Thursday, 2 October 2014 13:42:25 UTC-4, slelievre wrote:
Le mercredi 1 octobre 2014 22:06:50 UTC+2, NahsiN a écrit :
Hello, I don't know where to post this so redirect me as needed. I
believe I have found a typo in the sage tutorial. Under Sage Tutorial
v6.3
A Guided Tour Some Common Issues with Functions we have the
lines
def h(x):
if x2:
return 0
else:
return x-2
The issue: plot(h(x), 0, 4) plots the line y=x−2, not the multi-line
function defined by h. The reason? In the command plot(h(x),0, 4),
first
h(x) is evaluated: this means plugging x into the function h, *which
means that **x2** is evaluated*.
I think the else clause is evaluated and not the if x2 clause.
Thanks,
Nishan
You can work around this as follows:
plot(lambda x: h(x), 0, 4)
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Re: [sage-support] Inconsistency between Sage and Python
Ok, I had to make a huge effort to accept this, but it's more clear now. One last question: Why RDF does not incorporate this feature? because it comes from the GSL library, that is an independent project? or because its precision is known a priori, like the float type in Python? On Monday, October 6, 2014 3:39:32 PM UTC-3, Jeroen Demeyer wrote: On 2014-10-06 18:03, João Alberto wrote: Is this a correct behavior of Sage? It's a feature, not a bug. The reason is that the number of digits gives an idea about the precision of the number. Compare sage: RealField(20)(1) 1. sage: RealField(100)(1) 1. If both these would be printed as 1.0, you would lose this information about the precision. Python has a fixed precision of 53 bits and prints a minimal number of digits. -- You received this message because you are subscribed to the Google Groups sage-support group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
Re: [sage-support] Re: Typo in provided documentation
Dear Nishan,
I created a ticket for that, you can have a look at:
http://trac.sagemath.org/ticket/17107
Hopefully, this will be corrected in the next release of Sage.
Thanks for the report!
Vincent
2014-10-06 20:53 UTC+02:00, NahsiN nishan.singh.m...@gmail.com:
Yes Vincent, that sounds much better,
Cheers,
Nishan
On Saturday, 4 October 2014 05:21:15 UTC-4, vdelecroix wrote:
Hello,
Is it better worded as follows?
The issue: plot(h(x), 0, 4) plots the line y=x−2, not the multi-line
function defined by h. The reason? In the command plot(h(x), 0, 4),
first h(x) is evaluated: this means plugging the symbolic variable x
into the function h. The inequality x 2 evaluates to ``False`` and
hence ``h(x)`` evaluates to ``x - 2`` as it can be seen with
{{{
sage: bool(x 2)
False
sage: h(x)
x - 2
}}}
I also find misleading to have a Python argument (the x in def
h(x):) and a symbolic variable (here x) having the same name. At
least it should be mentioned.
Vincent
2014-10-02 20:32 UTC+02:00, NahsiN nishan.s...@gmail.com javascript::
@slelievre I was just pointing out what I think is a typo.
@slelievre You are right, the clause after the statement clarifies the
situation. When a symbolic equation is evaluated, as in the definition
of
h,
if it is not obviously true, then it returns False. Thus h(x) evaluates
to
x-2, and this is the function that gets plotted But I still feel the
whole
thing can be worded slightly better and more concisely. The if clause is
evaluated anyway when one calls h(x) so there is no point in saying x2
is
evaluated.
On Thursday, 2 October 2014 13:42:25 UTC-4, slelievre wrote:
Le mercredi 1 octobre 2014 22:06:50 UTC+2, NahsiN a écrit :
Hello, I don't know where to post this so redirect me as needed. I
believe I have found a typo in the sage tutorial. Under Sage Tutorial
v6.3
A Guided Tour Some Common Issues with Functions we have the
lines
def h(x):
if x2:
return 0
else:
return x-2
The issue: plot(h(x), 0, 4) plots the line y=x−2, not the multi-line
function defined by h. The reason? In the command plot(h(x),0, 4),
first
h(x) is evaluated: this means plugging x into the function h, *which
means that **x2** is evaluated*.
I think the else clause is evaluated and not the if x2 clause.
Thanks,
Nishan
You can work around this as follows:
plot(lambda x: h(x), 0, 4)
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