def tri(N, M=None, k=0, dtype=float):
""" returns a N-by-M array where all the diagonals starting from
lower left corner up to the k-th are all ones.
"""
if M is None: M = N
m = greater_equal(subtract.outer(arange(N), arange(M)), -k)
return m.astype(dtype)
def tri(N, M=None, k=0, dtype=float):
""" returns a N-by-M array where all the diagonals starting from
lower left corner up to the k-th are all ones.
"""
if M is None: M = N
m = greater_equal(subtract.outer(arange(N), arange(M)),-k)
return m.astype(dtype)
def eye(N, M=None, k=0, dtype=float):
""" eye returns a N-by-M 2-d array where the k-th diagonal is all ones,
and everything else is zeros.
"""
if M is None: M = N
m = equal(subtract.outer(arange(N), arange(M)), -k)
if m.dtype != dtype:
return m.astype(dtype)
def eye(N, M=None, k=0, dtype=float):
""" eye returns a N-by-M 2-d array where the k-th diagonal is all ones,
and everything else is zeros.
"""
if M is None: M = N
m = equal(subtract.outer(arange(N), arange(M)),-k)
if m.dtype != dtype:
return m.astype(dtype)
def eye(N, M=None, k=0, dtype=float):
"""
Return a 2-D array with ones on the diagonal and zeros elsewhere.
Parameters
----------
N : int
Number of rows in the output.
M : int, optional
Number of columns in the output. If None, defaults to `N`.
k : int, optional
Index of the diagonal: 0 refers to the main diagonal, a positive value
refers to an upper diagonal, and a negative value to a lower diagonal.
dtype : dtype, optional
Data-type of the returned array.
Returns
-------
I : ndarray (N,M)
An array where all elements are equal to zero, except for the `k`-th
diagonal, whose values are equal to one.
See Also
--------
diag : Return a diagonal 2-D array using a 1-D array specified by the user.
Examples
--------
>>> np.eye(2, dtype=int)
array([[1, 0],
[0, 1]])
>>> np.eye(3, k=1)
array([[ 0., 1., 0.],
[ 0., 0., 1.],
[ 0., 0., 0.]])
"""
if M is None:
M = N
m = equal(subtract.outer(arange(N), arange(M)), -k)
if m.dtype != dtype:
m = m.astype(dtype)
return m
def eye(N, M=None, k=0, dtype=float):
"""
Return a 2-D array with ones on the diagonal and zeros elsewhere.
Parameters
----------
N : int
Number of rows in the output.
M : int, optional
Number of columns in the output. If None, defaults to `N`.
k : int, optional
Index of the diagonal: 0 refers to the main diagonal, a positive value
refers to an upper diagonal, and a negative value to a lower diagonal.
dtype : dtype, optional
Data-type of the returned array.
Returns
-------
I : ndarray (N,M)
An array where all elements are equal to zero, except for the `k`-th
diagonal, whose values are equal to one.
See Also
--------
diag : Return a diagonal 2-D array using a 1-D array specified by the user.
Examples
--------
>>> np.eye(2, dtype=int)
array([[1, 0],
[0, 1]])
>>> np.eye(3, k=1)
array([[ 0., 1., 0.],
[ 0., 0., 1.],
[ 0., 0., 0.]])
"""
if M is None: M = N
m = equal(subtract.outer(arange(N), arange(M)),-k)
if m.dtype != dtype:
m = m.astype(dtype)
return m
def tri(N, M=None, k=0, dtype=float):
"""
An array with ones at and below the given diagonal and zeros elsewhere.
Parameters
----------
N : int
Number of rows in the array.
M : int, optional
Number of columns in the array.
By default, `M` is taken equal to `N`.
k : int, optional
The sub-diagonal at and below which the array is filled.
`k` = 0 is the main diagonal, while `k` < 0 is below it,
and `k` > 0 is above. The default is 0.
dtype : dtype, optional
Data type of the returned array. The default is float.
Returns
-------
tri : ndarray of shape (N, M)
Array with its lower triangle filled with ones and zero elsewhere;
in other words ``T[i,j] == 1`` for ``i <= j + k``, 0 otherwise.
Examples
--------
>>> np.tri(3, 5, 2, dtype=int)
array([[1, 1, 1, 0, 0],
[1, 1, 1, 1, 0],
[1, 1, 1, 1, 1]])
>>> np.tri(3, 5, -1)
array([[ 0., 0., 0., 0., 0.],
[ 1., 0., 0., 0., 0.],
[ 1., 1., 0., 0., 0.]])
"""
if M is None:
M = N
m = greater_equal(subtract.outer(arange(N), arange(M)),-k)
return m.astype(dtype)
