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Merge pull request #3 from cdeil/patch-1

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Python 3 !
This commit is contained in:
Nicolas P. Rougier 2015-08-19 07:24:58 +02:00
commit 7cdef30736
1 changed files with 62 additions and 62 deletions
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README.rst
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@ -18,7 +18,7 @@ is:
# Author: Somebody
print np.nonzero([1,2,0,0,4,0])
print(np.nonzero([1,2,0,0,4,0]))
Here is what the page looks like so far:
@ -41,7 +41,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
print np.__version__
print(np.__version__)
np.__config__.show()
@ -50,7 +50,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.zeros(10)
print Z
print(Z)
#. Create a null vector of size 10 but the fifth value which is 1
@ -59,7 +59,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.zeros(10)
Z[4] = 1
print Z
print(Z)
#. Create a vector with values ranging from 10 to 49
@ -67,7 +67,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.arange(10,50)
print Z
print(Z)
#. Create a 3x3 matrix with values ranging from 0 to 8
@ -75,7 +75,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.arange(9).reshape(3,3)
print Z
print(Z)
#. Find indices of non-zero elements from [1,2,0,0,4,0]
@ -83,7 +83,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
nz = np.nonzero([1,2,0,0,4,0])
print nz
print(nz)
#. Create a 3x3 identity matrix
@ -91,7 +91,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.eye(3)
print Z
print(Z)
#. Create a 5x5 matrix with values 1,2,3,4 just below the diagonal
@ -99,7 +99,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.diag(1+np.arange(4),k=-1)
print Z
print(Z)
#. Create a 3x3x3 array with random values
@ -107,7 +107,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.random.random((3,3,3))
print Z
print(Z)
#. Create a 8x8 matrix and fill it with a checkerboard pattern
@ -116,7 +116,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.zeros((8,8),dtype=int)
Z[1::2,::2] = 1
Z[::2,1::2] = 1
print Z
print(Z)
#. Create a 10x10 array with random values and find the minimum and maximum values
@ -125,7 +125,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.random.random((10,10))
Zmin, Zmax = Z.min(), Z.max()
print Zmin, Zmax
print(Zmin, Zmax)
#. Create a checkerboard 8x8 matrix using the tile function
@ -133,7 +133,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.tile( np.array([[0,1],[1,0]]), (4,4))
print Z
print(Z)
#. Normalize a 5x5 random matrix (between 0 and 1)
@ -141,9 +141,9 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.random.random((5,5))
Zmax,Zmin = Z.max(), Z.min()
Zmax, Zmin = Z.max(), Z.min()
Z = (Z - Zmin)/(Zmax - Zmin)
print Z
print(Z)
#. Multiply a 5x3 matrix by a 3x2 matrix (real matrix product)
@ -151,7 +151,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.dot(np.ones((5,3)), np.ones((3,2)))
print Z
print(Z)
#. Create a 5x5 matrix with row values ranging from 0 to 4
@ -160,7 +160,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.zeros((5,5))
Z += np.arange(5)
print Z
print(Z)
#. Create a vector of size 10 with values ranging from 0 to 1, both excluded
@ -168,7 +168,7 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
Z = np.linspace(0,1,12,endpoint=True)[1:-1]
print Z
print(Z)
#. Create a random vector of size 10 and sort it
@ -177,7 +177,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.random.random(10)
Z.sort()
print Z
print(Z)
#. Consider two random array A anb B, check if they are equal.
@ -187,7 +187,7 @@ Thanks to Michiaki Ariga, there is now a
A = np.random.randint(0,2,5)
B = np.random.randint(0,2,5)
equal = np.allclose(A,B)
print equal
print(equal)
#. Create a random vector of size 30 and find the mean value
@ -196,7 +196,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.random.random(30)
m = Z.mean()
print m
print(m)
#. Make an array immutable (read-only)
@ -217,8 +217,8 @@ Thanks to Michiaki Ariga, there is now a
X,Y = Z[:,0], Z[:,1]
R = np.sqrt(X**2+Y**2)
T = np.arctan2(Y,X)
print R
print T
print(R)
print(T)
#. Create random vector of size 10 and replace the maximum value by 0
@ -227,7 +227,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.random.random(10)
Z[Z.argmax()] = 0
print Z
print(Z)
#. Create a structured array with ``x`` and ``y`` coordinates covering the
@ -238,7 +238,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.zeros((10,10), [('x',float),('y',float)])
Z['x'], Z['y'] = np.meshgrid(np.linspace(0,1,10),
np.linspace(0,1,10))
print Z
print(Z)
#. Print the minimum and maximum representable value for each numpy scalar type
@ -246,12 +246,12 @@ Thanks to Michiaki Ariga, there is now a
.. code-block:: python
for dtype in [np.int8, np.int32, np.int64]:
print np.iinfo(dtype).min
print np.iinfo(dtype).max
print(np.iinfo(dtype).min)
print(np.iinfo(dtype).max)
for dtype in [np.float32, np.float64]:
print np.finfo(dtype).min
print np.finfo(dtype).max
print np.finfo(dtype).eps
print(np.finfo(dtype).min)
print(np.finfo(dtype).max)
print(np.finfo(dtype).eps)
#. Create a structured array representing a position (x,y) and a color (r,g,b)
@ -263,7 +263,7 @@ Thanks to Michiaki Ariga, there is now a
('color', [ ('r', float, 1),
('g', float, 1),
('b', float, 1)])])
print Z
print(Z)
#. Consider a random vector with shape (100,2) representing coordinates, find
@ -274,13 +274,13 @@ Thanks to Michiaki Ariga, there is now a
Z = np.random.random((10,2))
X,Y = np.atleast_2d(Z[:,0]), np.atleast_2d(Z[:,1])
D = np.sqrt( (X-X.T)**2 + (Y-Y.T)**2)
print D
print(D)
# Much faster with scipy
import scipy
Z = np.random.random((10,2))
D = scipy.spatial.distance.cdist(Z,Z)
print D
print(D)
#. Generate a generic 2D Gaussian-like array
@ -291,7 +291,7 @@ Thanks to Michiaki Ariga, there is now a
D = np.sqrt(X*X+Y*Y)
sigma, mu = 1.0, 0.0
G = np.exp(-( (D-mu)**2 / ( 2.0 * sigma**2 ) ) )
print G
print(G)
#. Subtract the mean of each row of a matrix
@ -316,7 +316,7 @@ Thanks to Michiaki Ariga, there is now a
# Author: Warren Weckesser
Z = np.random.randint(0,3,(3,10))
print (~Z.any(axis=0)).any()
print((~Z.any(axis=0)).any())
#. Find the nearest value from a given value in an array
@ -325,7 +325,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.random.uniform(0,1,10)
z = 0.5
m = Z.flat[np.abs(Z - z).argmin()]
print m
print(m)
#. Consider the following file::
@ -350,7 +350,7 @@ Thanks to Michiaki Ariga, there is now a
for x in xrange(10):
yield x
Z = np.fromiter(generate(),dtype=float,count=-1)
print Z
print(Z)
#. Consider a given vector, how to add 1 to each element indexed by a second
@ -363,7 +363,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.ones(10)
I = np.random.randint(0,len(Z),20)
Z += np.bincount(I, minlength=len(Z))
print Z
print(Z)
#. How to accumulate elements of a vector (X) to an array (F) based on an index
@ -376,7 +376,7 @@ Thanks to Michiaki Ariga, there is now a
X = [1,2,3,4,5,6]
I = [1,3,9,3,4,1]
F = np.bincount(I,X)
print F
print(F)
#. Considering a (w,h,3) image of (dtype=ubyte), compute the number of unique
@ -390,7 +390,7 @@ Thanks to Michiaki Ariga, there is now a
I = np.random.randint(0,2,(h,w,3)).astype(np.ubyte)
F = I[...,0]*256*256 + I[...,1]*256 +I[...,2]
n = len(np.unique(F))
print np.unique(I)
print(np.unique(I))
#. Considering a four dimensions array, how to get sum over the last two axis at once ?
@ -399,7 +399,7 @@ Thanks to Michiaki Ariga, there is now a
A = np.random.randint(0,10,(3,4,3,4))
sum = A.reshape(A.shape[:-2] + (-1,)).sum(axis=-1)
print
print(sum)
#. Considering a one-dimensional vector D, how to compute means of subsets of D
@ -414,7 +414,7 @@ Thanks to Michiaki Ariga, there is now a
D_sums = np.bincount(S, weights=D)
D_counts = np.bincount(S)
D_means = D_sums / D_counts
print D_means
print(D_means)
I often need to compute the equivalent of
@ -445,7 +445,7 @@ Thanks to Michiaki Ariga, there is now a
nz = 3
Z0 = np.zeros(len(Z) + (len(Z)-1)*(nz))
Z0[::nz+1] = Z
print Z0
print(Z0)
#. Consider an array of dimension (5,5,3), how to mulitply it by an array with
@ -455,7 +455,7 @@ Thanks to Michiaki Ariga, there is now a
A = np.ones((5,5,3))
B = 2*np.ones((5,5))
print A * B[:,:,None]
print(A * B[:,:,None])
#. How to swap two rows of an array ?
@ -467,7 +467,7 @@ Thanks to Michiaki Ariga, there is now a
A = np.arange(25).reshape(5,5)
A[[0,1]] = A[[1,0]]
print A
print(A)
#. Consider a one-dimensional array Z, build a two-dimensional array whose
@ -484,7 +484,7 @@ Thanks to Michiaki Ariga, there is now a
strides = (a.itemsize, a.itemsize)
return stride_tricks.as_strided(a, shape=shape, strides=strides)
Z = rolling(np.arange(10), 3)
print Z
print(Z)
#. Consider a set of 10 triplets describing 10 triangles (with shared
@ -500,7 +500,7 @@ Thanks to Michiaki Ariga, there is now a
F = np.sort(F,axis=1)
G = F.view( dtype=[('p0',F.dtype),('p1',F.dtype)] )
G = np.unique(G)
print G
print(G)
#. Given an array C that is a bincount, how to produce an array A such that
@ -512,7 +512,7 @@ Thanks to Michiaki Ariga, there is now a
C = np.bincount([1,1,2,3,4,4,6])
A = np.repeat(np.arange(len(C)), C)
print A
print(A)
#. How to compute averages using a sliding window over an array ?
@ -525,7 +525,7 @@ Thanks to Michiaki Ariga, there is now a
ret[n:] = ret[n:] - ret[:-n]
return ret[n - 1:] / n
Z = np.arange(20)
print moving_average(Z, n=3)
print(moving_average(Z, n=3))
#. How to get the documentation of the numpy add function from the command line ?
@ -555,8 +555,8 @@ Thanks to Michiaki Ariga, there is now a
Z = np.random.randint(0,5,(10,3))
E = np.logical_and.reduce(Z[:,1:] == Z[:,:-1], axis=1)
U = Z[~E]
print Z
print U
print(Z)
print(U)
#. Convert a vector of ints into a matrix binary representation.
@ -566,12 +566,12 @@ Thanks to Michiaki Ariga, there is now a
I = np.array([0, 1, 2, 3, 15, 16, 32, 64, 128])
B = ((I.reshape(-1,1) & (2**np.arange(8))) != 0).astype(int)
print B[:,::-1]
print(B[:,::-1])
# Author: Daniel T. McDonald
I = np.array([0, 1, 2, 3, 15, 16, 32, 64, 128], dtype=np.uint8)
print np.unpackbits(I[:, np.newaxis], axis=1)
print(np.unpackbits(I[:, np.newaxis], axis=1))
#. Consider 2 sets of points P0,P1 describing lines (2d) and a point p, how to
@ -590,7 +590,7 @@ Thanks to Michiaki Ariga, there is now a
P0 = np.random.uniform(-10,10,(10,2))
P1 = np.random.uniform(-10,10,(10,2))
p = np.random.uniform(-10,10,( 1,2))
print distance(P0, P1, p)
print(distance(P0, P1, p))
#. Consider 2 sets of points P0,P1 describing lines (2d) and a set of points P,
@ -632,8 +632,8 @@ Thanks to Michiaki Ariga, there is now a
r = [slice(start,stop) for start,stop in zip(R_start,R_stop)]
z = [slice(start,stop) for start,stop in zip(Z_start,Z_stop)]
R[r] = Z[z]
print Z
print R
print(Z)
print(R)
#. Consider an array Z = [1,2,3,4,5,6,7,8,9,10,11,12,13,14], how to generate an
@ -645,7 +645,7 @@ Thanks to Michiaki Ariga, there is now a
Z = np.arange(1,15,dtype=uint32)
R = stride_tricks.as_strided(Z,(11,4),(4,4))
print R
print(R)
#. Consider two arrays A and B of shape (8,3) and (2,2). How to find rows of A
@ -661,7 +661,7 @@ Thanks to Michiaki Ariga, there is now a
C = (A[..., np.newaxis, np.newaxis] == B)
rows = (C.sum(axis=(1,2,3)) >= B.shape[1]).nonzero()[0]
print rows
print(rows)
#. Extract all the contiguous 3x3 blocks from a random 10x10 matrix.
@ -675,7 +675,7 @@ Thanks to Michiaki Ariga, there is now a
i = 1 + (Z.shape[0]-3)
j = 1 + (Z.shape[1]-3)
C = stride_tricks.as_strided(Z, shape=(i, j, n, n), strides=Z.strides + Z.strides)
print C
print(C)
#. Create a 2D array subclass such that Z[i,j] == Z[j,i]
@ -695,7 +695,7 @@ Thanks to Michiaki Ariga, there is now a
S = symetric(np.random.randint(0,10,(5,5)))
S[2,3] = 42
print S
print(S)
#. Consider a set of p matrices wich shape (n,n) and a set of p vectors with shape (n,1).
How to compute the sum of of the p matrix products at once ? (result has shape (n,1))
@ -708,7 +708,7 @@ Thanks to Michiaki Ariga, there is now a
M = np.ones((p,n,n))
V = np.ones((p,n,1))
S = np.tensordot(M, V, axes=[[0, 2], [0, 1]])
print S
print(S)
# It works, because:
# M is (p,n,n)
@ -729,7 +729,7 @@ Thanks to Michiaki Ariga, there is now a
T = np.ascontiguousarray(Z).view(np.dtype((np.void, Z.dtype.itemsize * Z.shape[1])))
_, idx = np.unique(T, return_index=True)
uZ = Z[idx]
print uZ
print(uZ)
#. How to implement the Game of Life using numpy arrays ?