Thanks again to everyone who helped. The code is now working well and has
been reduced to:
def printSeries(expIn):
from sympy import degree
expOut = Add(*sorted(expIn.evalf(5).args, key=sympy.degree),
evaluate=False)
print(latex(expOut, order='none'))
Based on the post from Chris Smith, I tried the chatGPT. Specifically, I
used the newest version of Bing, which in turn used a new version of
chatGPT.
Here is a problem that I had
https://docs.sympy.org/latest/modules/printing.html#module-sympy.printing.latex
shows
sympy.printing.latex.latex
but
doprintLatex = sympy.printing.latex.latex(settings={'order':'None'}).doprint
raises
AttributeError: '_PrintFunction' object has no attribute 'latex'
Also
doprintLatex =
sympy.printing.latex.LatexPrinter(settings={'order':'None'}).doprint
raises
AttributeError: '_PrintFunction' object has no attribute 'LatexPrinter'
I gave that to the Bing chat that uses chatGPT and got this suggestion:
I see. It seems you are trying to create a custom instance of LatexPrinter
with your own settings. According to one of the web search results1, you
need to import LatexPrinter explicitly from sympy.printing.latex before
using it. For example:
from sympy import *
from sympy.printing.latex import LatexPrinter
my_printer = LatexPrinter(settings={"mul_symbol": "dot"})
var('x y z')
print(my_printer.doprint(x*y+y*z))
This should output:
x \cdot y + y \cdot z
Alternatively, you can use the latex() function with the same settings as
an argument. For example:
from sympy import *
var('x y z')
print(latex(x*y+y*z, mul_symbol="dot"))
The first suggestion reduces my code to
def printSeries(expIn):
from sympy import degree #, StrPrinter #, LatexPrinter
from sympy.printing.str import StrPrinter
from sympy.printing.latex import LatexPrinter
doprintStr = StrPrinter(settings={'order':'none'}).doprint
doprintLatex = LatexPrinter(settings={'order':'none'}).doprint
expOut = Add(*sorted(expIn.evalf(5).args, key=sympy.degree),
evaluate=False)
print(doprintStr(expOut))
print(doprintLatex(expOut))
But, I only wanted to print LaTeX, so the second suggestion reduces my code
to
def printSeries(expIn):
from sympy import degree
expOut = Add(*sorted(expIn.evalf(5).args, key=sympy.degree),
evaluate=False)
print(latex(expOut, order='none'))
On Tuesday, March 7, 2023 at 4:17:05 AM UTC+1 [email protected] wrote:
> When I pointed out " This gives an error. You have to split the ordered
> terms into coefficients and factors first with `as_coeff_Mul()`" it
> identified why the previous answer was incorrect and gave this modified
> line:
>
> expList = [(round(coeff, 5), t.as_poly()) for coeff, t in
> (term.as_coeff_Mul() for term in expList)]
>
> On Monday, March 6, 2023 at 9:08:45 PM UTC-6 Chris Smith wrote:
>
>> I thought I would try this in ChatGPT since one of the answers sounded
>> gpt-ish. Quite surprised by the results in terms of level of detail about
>> what is going on in the routine that it presented. I marked the line that
>> was needed to make the function of the gpt-answer work:
>>
>> def printSeries(expIn):
>> expOut = expIn
>> expOut = collect(expOut, t)
>> expList = expOut.as_ordered_terms() # convert expression to list
>> expList = [i.as_coeff_Mul() for i in expList] # <---- needed this
>> line
>> expList = [(t, round(coeff, 5)) for coeff, t in expList] # round
>> coefficients to 5 digits
>> expList.sort(key=lambda term: term[0].as_poly().degree(),
>> reverse=True) # sort terms by degree of t
>> expStr = ' '.join([f"{coeff:.5g} {t}" for t, coeff in expList]) #
>> format terms as strings
>> print(expStr)
>>
>> /c
>> On Monday, March 6, 2023 at 10:45:51 AM UTC-6 Oscar wrote:
>>
>>> The degree function can be imported like
>>>
>>> from sympy import degree
>>>
>>> It is used to get the degree of a polynomial expression.
>>>
>>> On Mon, 6 Mar 2023 at 14:53, Thomas Ligon <[email protected]> wrote:
>>> >
>>> > Thanks! That's a big help, but I am not finished yet. Here is where I
>>> am now:
>>> >
>>> > Step 1: Use your code.
>>> > name 'StrPrinter' is not defined
>>> > changed StrPrinter to sympy.printing.str.StrPrinter
>>> > https://docs.sympy.org/latest/modules/printing.html
>>> > name 'degree' is not defined
>>> > I tried key=sympy.printing.str.degree, but that gave me
>>> > module 'sympy.printing.str' has no attribute 'degree'
>>> > Then I tried key=sympy.degree and that worked.
>>> > Now the two series are being printed in the desired order.
>>> >
>>> > Step 2: Use latex
>>> > I tried changing print(doprint(series)) to
>>> print(latex(doprint(series)))
>>> > and the result is
>>> > \mathtt{\text{-2.565*t + 147.94*t**3 - 2867.7*t**5}}
>>> > which doesn't format correctly in Word's equation editor or in
>>> www.overleaf.com,
>>> > where it formats correctly, but issues an error
>>> > Undefined control sequence.
>>> > LaTeX Error: \mathtt allowed only in math mode.
>>> > I tried changing the string to
>>> > -2.565*t + 147.94*t**3 - 2867.7*t**5
>>> > and this formats correctly in Word and in Overleaf.
>>> > Then I tried
>>> > doprint =
>>> sympy.printing.latex.LatexPrinter(settings={'order':'none'}).doprint
>>> > but that throws an exception
>>> > '_PrintFunction' object has no attribute 'LatexPrinter'
>>> > even though the class
>>> > class sympy.printing.latex.LatexPrinter(settings=None)
>>> > is defined in
>>> >
>>> https://docs.sympy.org/latest/modules/printing.html#module-sympy.printing.latex
>>>
>>> >
>>> > Still to do:
>>> > Learn how this works.
>>> > Learn why evalf(5) works. The documentation at
>>> > https://docs.sympy.org/latest/modules/evalf.html
>>> > doesn't make it clear to me what the possible arguments are and what
>>> they mean.
>>> > Find documentation for sorted and key=degree.
>>> > I searched for sympy degree and found polynomials and angles, but
>>> still don't understand this one.
>>> >
>>> >
>>> > On Sunday, March 5, 2023 at 8:53:32 PM UTC+1 Oscar wrote:
>>> >
>>> > On Sun, 5 Mar 2023 at 08:32, Thomas Ligon <[email protected]>
>>> wrote:
>>> > >
>>> > > I have a lot of power series that look like this (but going up to
>>> t**12):
>>> > > exp1 = -2867.70035529489*t**5 + 147.938724526848*t**3 -
>>> 2.56500070531002*t
>>> > > While trying to gain some insight into the mathematics that creates
>>> them, I want to print a shorter version, such as
>>> > > - 2.565 t + 147.93872 t**3- 2867.70036 t**5
>>> > > but the best I have achieved is
>>> > > - 2867.70036 t^{5} + \left(147.93872 t^{3} - 2.565 t\right)
>>> > > Rounding the numbers was easy, but I would prefer to round to 5
>>> digits total, not 5 digits after the decimal point. I was able to convert
>>> the expression to a list and sort the list, but when I converted the list
>>> back to an expression, I didn't succeed in producing the order I wanted.
>>> >
>>> > You can get 5 digits by using exp1.evalf(5).
>>> >
>>> > It is surprisingly difficult to control the order of terms in sympy's
>>> > printing functionality but it is possible:
>>> >
>>> > In [1]: exp1 = -2867.70035529489*t**5 + 147.938724526848*t**3 -
>>> > 2.56500070531002*t
>>> >
>>> > In [2]: doprint = StrPrinter(settings={'order':'none'}).doprint
>>> >
>>> > In [3]: series = Add(*sorted(exp1.evalf(5).args, key=degree),
>>> evaluate=False)
>>> >
>>> > In [4]: print(doprint(series))
>>> > -2.565*t + 147.94*t**3 - 2867.7*t**5
>>> >
>>> > There are two steps to controlling the order:
>>> >
>>> > - Ordering the terms in the expression itself (the series variable
>>> above).
>>> > - Getting the printer to respect that ordering ('order':'none').
>>> >
>>> > It should be possible to set order=None with init_printing and that
>>> > does work for the pretty printer but not for string printing (i.e.
>>> > print(expr) or str(expr)).
>>> >
>>> > --
>>> > Oscar
>>> >
>>> > --
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>>> Groups "sympy" group.
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>>> https://groups.google.com/d/msgid/sympy/d48be44a-e979-41fd-aa37-1fabadde9b7an%40googlegroups.com.
>>>
>>>
>>>
>>
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