Mailman 3 February 2017 - NumPy-Discussion

Marten van Kerkwijk added to numpy team.
by Charles R Harris 14 Feb '17

14 Feb '17

Hi All, I'm pleased to welcome Marten to the numpy team. His reviews of PRs have been very useful in the past and I am happy that he has accepted our invitation to join the team. Cheers, Chuck

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zero values in the output of PyArray_AsCArray(
by Boukhdhir Amal 07 Feb '17

07 Feb '17

Hi, I am trying to access an array as a C-Type using the function 'PyArray_AsCArray'The problem is that I am getting many 0 values in the resulting C- array. Some of the indexedvalues are correct. This is my code: static PyObject* cos_func_np(PyObject* self, PyObject* args){ PyObject *in_array_object; PyObject *out_array; int** segs_2d_array; /* Parse single numpy array argument*/ if (! PyArg_ParseTuple(args, "O", &in_array_object)) return NULL; int typenum = NPY_INT64; PyArray_Descr *descr; descr = PyArray_DescrFromType(typenum); npy_intp dims[2]; PyArray_AsCArray(&in_array_object, (void**) &segs_2d_array, dims, 2, descr); printf("\n-segs_2d_array: %d --\n", segs_2d_array[1][5]); //return Py_BuildValue("O", in_array_object); } For example:segs_2d_array[0][0] and segs_2d_array[1][2] outputs the correct values, however, segs_2d_array[1][3] and segs_2d_array[1][5] are equal to zero. What is wrong with this code please ?

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composing Euler rotation matrices
by Seb 01 Feb '17

01 Feb '17

Hello, I'm trying to compose Euler rotation matrices shown in https://en.wikipedia.org/wiki/Euler_angles#Rotation_matrix. For example, The Z1Y2X3 Tait-Bryan rotation shown in the table can be represented in Numpy using the function: def z1y2x3(alpha, beta, gamma): """Rotation matrix given Euler angles""" return np.array([[np.cos(alpha) * np.cos(beta), np.cos(alpha) * np.sin(beta) * np.sin(gamma) - np.cos(gamma) * np.sin(alpha), np.sin(alpha) * np.sin(gamma) + np.cos(alpha) * np.cos(gamma) * np.sin(beta)], [np.cos(beta) * np.sin(alpha), np.cos(alpha) * np.cos(gamma) + np.sin(alpha) * np.sin(beta) * np.sin(gamma), np.cos(gamma) * np.sin(alpha) * np.sin(beta) - np.cos(alpha) * np.sin(gamma)], [-np.sin(beta), np.cos(beta) * np.sin(gamma), np.cos(beta) * np.cos(gamma)]]) which given alpha, beta, gamma as: angles = np.radians(np.array([30, 20, 10])) returns the following matrix: In [31]: z1y2x3(angles[0], angles[1], angles[2]) Out[31]: array([[ 0.81379768, -0.44096961, 0.37852231], [ 0.46984631, 0.88256412, 0.01802831], [-0.34202014, 0.16317591, 0.92541658]]) If I understand correctly, one should be able to compose this matrix by multiplying the rotation matrices that it is made of. However, I cannot reproduce this matrix via composition; i.e. by multiplying the underlying rotation matrices. Any tips would be appreciated. -- Seb

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ANN: xarray v0.9 released
by Stephan Hoyer 01 Feb '17

01 Feb '17

I'm pleased to announce the release of the latest major version of xarray, v0.9. xarray is an open source project and Python package that provides a toolkit and data structures for N-dimensional labeled arrays. Its approach combines an API inspired by pandas with the Common Data Model for self-described scientific data. This release includes five months worth of enhancements and bug fixes from 24 contributors, including some significant enhancements to the data model that are not fully backwards compatible. Highlights include: - Coordinates are now optional in the xarray data model, even for dimensions. - Changes to caching, lazy loading and pickling to improve xarray’s experience for parallel computing. - Improvements for accessing and manipulating pandas.MultiIndex levels. - Many new methods and functions, including quantile(), cumsum(), cumprod(), combine_firstset_index(), reset_index(), reorder_levels(), full_like(), zeros_like(), ones_like(), open_dataarray(), compute(), Dataset.info(), testing.assert_equal(), testing.assert_identical(), and testing.assert_allclose(). For more details, read the full release notes: http://xarray.pydata.org/en/latest/whats-new.html You can install xarray with pip or conda: pip install xarray conda install -c conda-forge xarray Best, Stephan

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Fwd: Installation Problem
by Naresh P 01 Feb '17

01 Feb '17

*Warm Regards,* *Naresh* *Developer * *Consumer Goods Myanmar Limited ( CGM )No.15, Junction Square Complex, 37-G, Pyay Road,**13041 Kamayut Township**, Yangon, Myanmar.* *Tel: +959979867914* http://www.cg-m.com ---------- Forwarded message ---------- From: <numpy-discussion-owner(a)scipy.org> Date: Wed, Feb 1, 2017 at 2:59 PM Subject: Fwd: Installation Problem To: naresh.p(a)okdollar.com This is a members-only list. Your message has been automatically rejected, since it came from a non-member's email address. Please make sure to use the email account that you used to join this list. ---------- Forwarded message ---------- From: Naresh P <naresh.p(a)okdollar.com> To: numpy-discussion(a)scipy.org Cc: Date: Wed, 1 Feb 2017 14:59:08 +0630 Subject: Fwd: Installation Problem *Warm Regards,* *Naresh* *Developer * *Consumer Goods Myanmar Limited ( CGM )No.15, Junction Square Complex, 37-G, Pyay Road,**13041 Kamayut Township**, Yangon, Myanmar.* *Tel: +959979867914* http://www.cg-m.com On Wed, Feb 1, 2017 at 2:54 PM, <numpy-discussion-owner(a)scipy.org> wrote: > This is a members-only list. Your message has been automatically > rejected, since it came from a non-member's email address. Please > make sure to use the email account that you used to join this list. > > > > ---------- Forwarded message ---------- > From: Naresh P <naresh.p(a)okdollar.com> > To: numpy-discussion(a)scipy.org > Cc: > Date: Wed, 1 Feb 2017 14:54:21 +0630 > Subject: Fwd: Installation Problem > Hi Team, > > i have still that problem , can please help me. > > let me know , i don't know how get ur membership , > > Thanks > > > > *Warm Regards,* > *Naresh* > *Developer * > *Consumer Goods Myanmar Limited ( CGM )No.15, Junction Square > Complex, 37-G, Pyay Road,**13041 Kamayut Township**, Yangon, Myanmar.* > *Tel: +959979867914* > http://www.cg-m.com > > ---------- Forwarded message ---------- > From: Naresh P <naresh.p(a)okdollar.com> > Date: Tue, Jan 31, 2017 at 3:20 PM > Subject: Installation Problem > To: numpy-discussion(a)scipy.org > > > > Hi , > i tried to somany times , but not install ,below msg are display. > help me > > > [image: Inline image 1] > > > *Warm Regards,* > *Naresh* > *Developer * > *Consumer Goods Myanmar Limited ( CGM )No.15, Junction Square > Complex, 37-G, Pyay Road,**13041 Kamayut Township**, Yangon, Myanmar.* > *Tel: +959979867914* > http://www.cg-m.com > > >

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NumPy-Discussion February 2017