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Cuchulainn
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Re: Python tricks

August 20th, 2019, 7:54 am

Undocumented code?(?)
 
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Cuchulainn
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Re: Python tricks

August 21st, 2019, 4:35 pm

np.allclose() is kind of handy
 
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Cuchulainn
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Re: Python tricks

September 3rd, 2019, 8:37 pm

Indentation is scary; 2 code block that run but give different answers
one TAB too many means 0.5 versus 0.98
for n in range(N):
        ynP1 = y + h*f(x+h/2, y + h*f(x,y)/2)

		# Go to next level
        x += h;
        y = ynP1;

    return ynP1

OR

 for n in range(N):
        ynP1 = y + h*f(x+h/2, y + h*f(x,y)/2)

		# Go to next level
        x += h;
        y = ynP1;

        return ynP1
 
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FaridMoussaoui
Posts: 412
Joined: June 20th, 2008, 10:05 am
Location: Genève, Genf, Ginevra, Geneva

Re: Python tricks

September 4th, 2019, 7:17 pm

my everything editor is emacs. The (right) tabing is done automagically through plugins.
For python, I use Tim Peters plugin available here https://launchpad.net/python-mode
Last edited by FaridMoussaoui on September 6th, 2019, 7:30 am, edited 1 time in total.
 
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ISayMoo
Posts: 1987
Joined: September 30th, 2015, 8:30 pm

Re: Python tricks

September 4th, 2019, 11:11 pm

Indentation is scary; 2 code block that run but give different answers
one TAB too many means 0.5 versus 0.98
for n in range(N):
        ynP1 = y + h*f(x+h/2, y + h*f(x,y)/2)

 # Go to next level
        x += h;
        y = ynP1;

    return ynP1

OR

 for n in range(N):
        ynP1 = y + h*f(x+h/2, y + h*f(x,y)/2)

 # Go to next level
        x += h;
        y = ynP1;

        return ynP1
The first one would not pass the linter. No indentation without an if, for etc.
 
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Cuchulainn
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Location: Amsterdam
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Re: Python tricks

September 11th, 2019, 10:05 am

scipy.optimize is super to use.
Now why can't the C++ folk (Boost) just do the same by creating a wrapper for those original Fortran and C libraries.
Named parameters are a godsend. Boost has them but not {C++11,C++20]??
 
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Cuchulainn
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Re: Python tricks

September 11th, 2019, 10:21 am

Indentation is scary; 2 code block that run but give different answers
one TAB too many means 0.5 versus 0.98

The first one would not pass the linter. No indentation without an if, for etc.
Can we see the linter as a pre-compiler that we need to 'execute' before running?
 
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ISayMoo
Posts: 1987
Joined: September 30th, 2015, 8:30 pm

Re: Python tricks

September 11th, 2019, 10:27 am

Yes, And mypy for type annotations.
 
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ISayMoo
Posts: 1987
Joined: September 30th, 2015, 8:30 pm

Re: Python tricks

September 11th, 2019, 10:28 am

scipy.optimize is super to use.
Now why can't the C++ folk (Boost) just do the same by creating a wrapper for those original Fortran and C libraries.
I am sure you know this library: https://nlopt.readthedocs.io/en/latest/
 
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Cuchulainn
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Re: Python tricks

September 11th, 2019, 4:48 pm

scipy.optimize is super to use.
Now why can't the C++ folk (Boost) just do the same by creating a wrapper for those original Fortran and C libraries.
I am sure you know this library: https://nlopt.readthedocs.io/en/latest/
Cool. I installed it from Python and ran a POC test. Looks good. Just that
def myfunc(x, grad):

    return -1

not work while (invalid argument)
def myfunc(x, grad):

    return -1.0

did.

hmmm..
 
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FaridMoussaoui
Posts: 412
Joined: June 20th, 2008, 10:05 am
Location: Genève, Genf, Ginevra, Geneva

Re: Python tricks

September 11th, 2019, 7:13 pm

If you check the source code on github,  it expects a double as an output for the function. If not,  it will throw an invalid argument error message.
 
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Cuchulainn
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Re: Python tricks

September 12th, 2019, 7:49 am

If you check the source code on github,  it expects a double as an output for the function. If not,  it will throw an invalid argument error message.
I used 1. instead of 1 myself (in FORTRAN REAL*x = 1.0,  x .EQ. 1 always FALSE afair), newbies might get confused. I wonder where and by whom this type checking takes place?
I manage to pip nlopt directly.
Looks like a nice library.
 
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FaridMoussaoui
Posts: 412
Joined: June 20th, 2008, 10:05 am
Location: Genève, Genf, Ginevra, Geneva

Re: Python tricks

September 12th, 2019, 8:23 am

Looking to source code, you can also see how to use SWIG to interface the C library to python.

If possible, I always install "packages" from source code. That's a good practise I learned working on Linux.
 
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Cuchulainn
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Joined: July 16th, 2004, 7:38 am
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Re: Python tricks

September 12th, 2019, 9:33 am

Looking to source code, you can also see how to use SWIG to interface the C library to python.

If possible, I always install "packages" from source code. That's a good practise I learned working on Linux.
Good point. 

Having precise black-box contract specifications would obviate the need for source code inspection.
 
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Cuchulainn
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Joined: July 16th, 2004, 7:38 am
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Re: Python tricks

September 12th, 2019, 8:18 pm

any one use scipy.interpolate.KroghInterpolate?
a bit quaint or maybe lost in action?
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