import numpy as np
import math
print -1/2*np.log2(1/2)-1/2*np.log2(1/2)
prints nan
Can you explain?
change python version as well
The first is python 2.7, the second is python 3.5
>>> import numpy as np
>>> print(-1/2*np.log2(1/2)-1/2*np.log2(1/2))
nan
>>> print(-1/2*np.log2(1/2)-1/2*np.log2(1/2))
1.0
More information requested...
>>> import numpy as np
>>> print(-1/2*np.log2(1/2)-1/2*np.log2(1/2))
__main__:1: RuntimeWarning: divide by zero encountered in log2
__main__:1: RuntimeWarning: invalid value encountered in double_scalars
nan
Now this can be avoided by floating your terms... the easiest ways is to do it directly...
>>> import numpy as np
>>> print(-1/2.*np.log2(1/2.)-1/2.*np.log2(1/2.))
1.0
Same numpy version, just python has changed between 2.7 and 3.5
In python 2.x division between ints is euclidean division, so 1/2 is 0, and np.log(0) returns nan.
Using python 3:
Python 3.5.2 |Anaconda 4.2.0 (64-bit)| (default, Jul 2 2016, 17:53:06)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux
>>> 1/2
0.5
whereas in python 2:
Python 2.7.12 |Continuum Analytics, Inc.| (default, Jul 2 2016, 17:42:40)
[GCC 4.4.7 20120313 (Red Hat 4.4.7-1)] on linux2
>>> 1/2
0
>>> 1./2
0.5
>>> from __future__ import division
>>> 1/2
0.5
I have included two ways to get ordinary division in python 2: using a float (1. instead of 1) or importing division from __future __
Related
I´m trying to read a shapefile with geopandas
Quito_full =gpd.read_file('./shapefiles/administraciones_zonales.shp')
Simple as that but I keep getting the following error
CRSError: Invalid projection: epsg:32717: (Internal Proj Error: proj_create: SQLite error on SELECT name, coordinate_system_auth_name, coordinate_system_code, geodetic_crs_auth_name, geodetic_crs_code, conversion_auth_name, conversion_code, area_of_use_auth_name, area_of_use_code, text_definition, deprecated FROM projected_crs WHERE auth_name = ? AND code = ?: no such column: area_of_use_auth_name)
This are my versions
print(sys.version)
3.8.12 (default, Oct 12 2021, 03:01:40) [MSC v.1916 64 bit (AMD64)]
import pyproj
print(pyproj.__version__)
2.6.1.post1
import geopandas
print(geopandas.__version__)
0.9.0
Is there anyway to fix this error, I have been trying everything!.
have downloaded shape file from here https://hub.arcgis.com/datasets/esrimarketing::administraciones-zonales/explore?location=-0.167571%2C-78.559309%2C10.38
it is epsg:4326, but then projected to epsg:32717. No issues
your pyproj and geopandas versions are a bit outdated. Your error primarily points to an issue with pyproj
from pathlib import Path
import geopandas as gpd
gdf = gpd.read_file(list(Path.home().joinpath("Downloads").glob("**/Administraciones_Zonales.shp"))[0])
gdf.to_crs("epsg:32717").explore()
versions
import pyproj, sys
print(gpd.__version__, pyproj.__version__, sys.version)
0.10.2 3.3.0 3.9.10 (main, Jan 15 2022, 11:48:00)
[Clang 13.0.0 (clang-1300.0.29.3)]
I am working in Ubuntu 18.04. - Linux distro.
When I use Python I have no problem producing my graphs, tables and plots output.
When I switch to IPython instead of the expected table I get
Figure size 432x288 with 1 Axes
This is the script I am using from Dr. Hilpisch Python for finance O'Reilly books
Python 3.8.5 (default, Sep 4 2020, 07:30:14)
Type 'copyright', 'credits' or 'license' for more information
IPython 7.18.1 -- An enhanced Interactive Python. Type '?' for help.
In [1]: import matplotlib as mpl
In [2]: mpl.version
Out[2]: '3.3.2'
In [3]: import matplotlib.pyplot as plt
In [4]: plt.style.use('seaborn')
In [5]: mpl.rcParams['font.family'] = 'serif'
In [6]: %matplotlib inline
In [7]: import numpy as np
In [8]: np.random.seed(1000)
In [9]: y = np.random.standard_normal(20)
In [10]: x = np.arange(len(y))
In [11]: plt.plot(x, y);
Figure size 432x288 with 1 Axes
Thank You for your help
I'm trying to accelerate some numpy code with cupy, but I'm getting some unexpected results.
I'm running this on a Mac Pro Late 2013, OSX 10.13.6 using a NVIDIA GeForce GTX 1080 Ti.
I have been able to reproduce an error in ipython shown below. When determining a norm the multiplication of the conjugate with itself should give a real number. In numpy this is as expected, but using cupy I end up with an imaginary part.
In [54]: import numpy as np
In [55]: import cupy as cp
In [56]: q = np.arange(4)
In [57]: q.shape=[2,2]
In [58]: q=(0.23+0.33j)*(q+0.43)
In [59]: np.dot(np.conj(q).flatten(),q.flatten())
Out[59]: (3.21975528+0j)
In [60]: q_gpu = cp.asarray(q)
In [61]: cp.dot(cp.conj(q_gpu).flatten(),q_gpu.flatten())
Out[61]: array(3.21975528-1.93612215e-17j)
In [62]: cp.sum(cp.abs(q_gpu)**2)
Out[62]: array(3.21975528)
In [63]: sys.version
Out[63]: '3.7.3 | packaged by conda-forge | (default, Jul 1 2019, 14:38:56) \n[Clang 4.0.1 (tags/RELEASE_401/final)]'
In [64]: sys.version_info
Out[64]: sys.version_info(major=3, minor=7, micro=3, releaselevel='final', serial=0)
I have realized other inconsistencies in precision between running code in cupy vs. numpy.
What am I doing wrong?
I try to do the following
from scipy import *
from numpy import *
import scipy as s
import numpy as np
import math
import scipy.sparse as l
from plot import Graph3DSolution
import numpy.linalg as lin
currentSol=s.sparse.linalg.inv(I-C)*A*lastSol
Im missing out some code but the issue is this
Traceback (most recent call last):
File "explict1wave.py", line 62, in <module>
currentSol=s.sparse.linalg.inv(I-C)*A*lastSol
AttributeError: 'module' object has no attribute 'linalg'
Python 2.7.6 |Anaconda 1.9.1 (x86_64)| (default, Jan 10 2014, 11:23:15)
[GCC 4.0.1 (Apple Inc. build 5493)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
im>>> import scipy
>>> scipy.__version__
'0.14.0'
>>>
I look up the documentation and it seems these libraries existed since .12 . I dont know what the issue is, but im sure its something simple im not seeing.
>>> import scipy as s
>>> s.sparse
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
AttributeError: 'module' object has no attribute 'sparse'
>>>
>>> from scipy.sparse import linalg
>>> linalg.inv
<function inv at 0x19b1758>
>>>
General recommendations for importing functions from scipy .
On a side note, best avoid star imports. These from scipy import *, from numpy import * are not recommended and not needed here. Same for import scipy as s.
I am running ActiveState Python 3.2, and getting this cryptic error:
D:\code>python
ActivePython 3.2.1.2 (ActiveState Software Inc.) based on
Python 3.2.1 (default, Jul 18 2011, 14:31:09) [MSC v.1500 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import numpy as np
>>> x = np.array([[1, 1], [2, 1], [3, 1]])
>>> y = np.array([3, 4, 5])
>>> be = np.linalg.lstsq(x,y)
MKL ERROR: Parameter 5 was incorrect on entry to DGELSD
MKL ERROR: Parameter 5 was incorrect on entry to DGELSD
>>>
Does anyone know what might be going on?
There seems to be no answer to that. The best I can do is provide the link to my bug report to ActiveState which is now being looked into.