本文整理汇总了Python中numpy.core.numeric.where函数的典型用法代码示例。如果您正苦于以下问题:Python where函数的具体用法?Python where怎么用?Python where使用的例子?那么恭喜您, 这里精选的函数代码示例或许可以为您提供帮助。
在下文中一共展示了where函数的14个代码示例,这些例子默认根据受欢迎程度排序。您可以为喜欢或者感觉有用的代码点赞,您的评价将有助于我们的系统推荐出更棒的Python代码示例。
示例1: __train__
def __train__(self, data, labels):
l = labels.reshape((-1,1))
self.__trainingData__ = data
self.__trainingLabels__ = l
N = len(l)
H = zeros((N,N))
for i in range(N):
for j in range(N):
H[i,j] = self.__trainingLabels__[i]*self.__trainingLabels__[j]*self.__kernelFunc__(self.__trainingData__[i],self.__trainingData__[j])
f = -1.0*ones(labels.shape)
lb = zeros(labels.shape)
ub = self.C * ones(labels.shape)
Aeq = labels
beq = 0.0
suppressOut = True
if suppressOut:
devnull = open('/dev/null', 'w')
oldstdout_fno = os.dup(sys.stdout.fileno())
os.dup2(devnull.fileno(), 1)
p = QP(matrix(H),f.tolist(),lb=lb.tolist(),ub=ub.tolist(),Aeq=Aeq.tolist(),beq=beq)
r = p.solve('cvxopt_qp')
if suppressOut:
os.dup2(oldstdout_fno, 1)
lim = 1e-4
r.xf[where(abs(r.xf)<lim)] = 0
self.__lambdas__ = r.xf
nonzeroindexes = where(r.xf>lim)[0]
# l1 = nonzeroindexes[0]
# self.w0 = 1.0/labels[l1]-dot(self.w,data[l1])
self.numSupportVectors = len(nonzeroindexes)
开发者ID:yk,项目名称:patternhs12,代码行数:30,代码来源:classifiers.py
示例2: triu
def triu(m, k=0):
"""
Upper triangle of an array.
Return a copy of a matrix with the elements below the `k`-th diagonal
zeroed.
Please refer to the documentation for `tril` for further details.
See Also
--------
tril : lower triangle of an array
Examples
--------
>>> np.triu([[1,2,3],[4,5,6],[7,8,9],[10,11,12]], -1)
array([[ 1, 2, 3],
[ 4, 5, 6],
[ 0, 8, 9],
[ 0, 0, 12]])
"""
m = asanyarray(m)
mask = tri(*m.shape[-2:], k=k-1, dtype=bool)
return where(mask, zeros(1, m.dtype), m)
开发者ID:AlerzDev,项目名称:Brazo-Proyecto-Final,代码行数:26,代码来源:twodim_base.py
示例3: calcN
def calcN(classKernels, trainLabels):
N = zeros((len(trainLabels), len(trainLabels)))
for i, l in enumerate(unique(trainLabels)):
numExamplesWithLabel = len(where(trainLabels == l)[0])
Idiff = identity(numExamplesWithLabel, Float64) - (1.0 / numExamplesWithLabel) * ones(numExamplesWithLabel, Float64)
firstDot = dot(classKernels[i], Idiff)
labelTerm = dot(firstDot, transpose(classKernels[i]))
N += labelTerm
N = nan_to_num(N)
#make N more numerically stable
#if I had more time, I would train this parameter, but I don't
additionToN = ((mean(diag(N)) + 1) / 100.0) * identity(N.shape[0], Float64)
N += additionToN
#make sure N is invertable
for i in range(1000):
try:
inv(N)
except LinAlgError:
#doing this to make sure the maxtrix is invertable
#large value supported by section titled
#"numerical issues and regularization" in the paper
N += additionToN
return N
开发者ID:Primer42,项目名称:TuftComp136,代码行数:25,代码来源:main.py
示例4: train
def train(self, data, labels):
l = labels.reshape((-1,1))
xy = data * l
H = dot(xy,transpose(xy))
f = -1.0*ones(labels.shape)
lb = zeros(labels.shape)
ub = self.C * ones(labels.shape)
Aeq = labels
beq = 0.0
p = QP(matrix(H),f.tolist(),lb=lb.tolist(),ub=ub.tolist(),Aeq=Aeq.tolist(),beq=beq)
r = p.solve('cvxopt_qp')
r.xf[where(r.xf<1e-3)] = 0
self.w = dot(r.xf*labels,data)
nonzeroindexes = where(r.xf>1e-4)[0]
l1 = nonzeroindexes[0]
self.w0 = 1.0/labels[l1]-dot(self.w,data[l1])
self.numSupportVectors = len(nonzeroindexes)
开发者ID:yk,项目名称:patternhs12,代码行数:17,代码来源:classifiers.py
示例5: bartlett
def bartlett(M):
"""bartlett(M) returns the M-point Bartlett window.
"""
if M < 1:
return array([])
if M == 1:
return ones(1, float)
n = arange(0,M)
return where(less_equal(n,(M-1)/2.0),2.0*n/(M-1),2.0-2.0*n/(M-1))
开发者ID:ruschecker,项目名称:DrugDiscovery-Home,代码行数:9,代码来源:function_base.py
示例6: getClassKernels
def getClassKernels(fullKernelMatrix, trainLabels):
#create a matrix where rows correspond to all examples
#and columns correspond to examples of a specific class
#so if l is the total number of examples, and lj is the number of examples in class j
#then we're creating an l x lj matrix
uniqueLabels = unique(trainLabels)
ret = []
for l in uniqueLabels:
labelIndexes = where(trainLabels == l)[0]
k = zeros((len(fullKernelMatrix), len(labelIndexes)))
for r in range(len(k)):
for c in range(len(k[r])):
k[r][c] = fullKernelMatrix[r][labelIndexes[c]]
ret.append(k)
return ret
开发者ID:Primer42,项目名称:TuftComp136,代码行数:15,代码来源:main.py
示例7: fix
def fix(x, y=None):
"""
Round to nearest integer towards zero.
Round an array of floats element-wise to nearest integer towards zero.
The rounded values are returned as floats.
Parameters
----------
x : array_like
An array of floats to be rounded
y : ndarray, optional
Output array
Returns
-------
out : ndarray of floats
The array of rounded numbers
See Also
--------
trunc, floor, ceil
around : Round to given number of decimals
Examples
--------
>>> np.fix(3.14)
3.0
>>> np.fix(3)
3.0
>>> np.fix([2.1, 2.9, -2.1, -2.9])
array([ 2., 2., -2., -2.])
"""
x = nx.asanyarray(x)
y1 = nx.floor(x)
y2 = nx.ceil(x)
if y is None:
y = nx.asanyarray(y1)
y[...] = nx.where(x >= 0, y1, y2)
return y
开发者ID:258073127,项目名称:MissionPlanner,代码行数:41,代码来源:ufunclike.py
示例8: tril
def tril(m, k=0):
"""
Lower triangle of an array.
Return a copy of an array with elements above the `k`-th diagonal zeroed.
Parameters
----------
m : array_like, shape (M, N)
Input array.
k : int, optional
Diagonal above which to zero elements. `k = 0` (the default) is the
main diagonal, `k < 0` is below it and `k > 0` is above.
Returns
-------
tril : ndarray, shape (M, N)
Lower triangle of `m`, of same shape and data-type as `m`.
See Also
--------
triu : same thing, only for the upper triangle
Examples
--------
>>> np.tril([[1,2,3],[4,5,6],[7,8,9],[10,11,12]], -1)
array([[ 0, 0, 0],
[ 4, 0, 0],
[ 7, 8, 0],
[10, 11, 12]])
"""
m = asanyarray(m)
mask = tri(*m.shape[-2:], k=k, dtype=bool)
return where(mask, m, zeros(1, m.dtype))
开发者ID:AlerzDev,项目名称:Brazo-Proyecto-Final,代码行数:36,代码来源:twodim_base.py
示例9: mask_indices
def mask_indices(n, mask_func, k=0):
"""
Return the indices to access (n, n) arrays, given a masking function.
Assume `mask_func` is a function that, for a square array a of size
``(n, n)`` with a possible offset argument `k`, when called as
``mask_func(a, k)`` returns a new array with zeros in certain locations
(functions like `triu` or `tril` do precisely this). Then this function
returns the indices where the non-zero values would be located.
Parameters
----------
n : int
The returned indices will be valid to access arrays of shape (n, n).
mask_func : callable
A function whose call signature is similar to that of `triu`, `tril`.
That is, ``mask_func(x, k)`` returns a boolean array, shaped like `x`.
`k` is an optional argument to the function.
k : scalar
An optional argument which is passed through to `mask_func`. Functions
like `triu`, `tril` take a second argument that is interpreted as an
offset.
Returns
-------
indices : tuple of arrays.
The `n` arrays of indices corresponding to the locations where
``mask_func(np.ones((n, n)), k)`` is True.
See Also
--------
triu, tril, triu_indices, tril_indices
Notes
-----
.. versionadded:: 1.4.0
Examples
--------
These are the indices that would allow you to access the upper triangular
part of any 3x3 array:
>>> iu = np.mask_indices(3, np.triu)
For example, if `a` is a 3x3 array:
>>> a = np.arange(9).reshape(3, 3)
>>> a
array([[0, 1, 2],
[3, 4, 5],
[6, 7, 8]])
>>> a[iu]
array([0, 1, 2, 4, 5, 8])
An offset can be passed also to the masking function. This gets us the
indices starting on the first diagonal right of the main one:
>>> iu1 = np.mask_indices(3, np.triu, 1)
with which we now extract only three elements:
>>> a[iu1]
array([1, 2, 5])
"""
m = ones((n,n), int)
a = mask_func(m, k)
return where(a != 0)
开发者ID:RJSSimpson,项目名称:numpy,代码行数:68,代码来源:twodim_base.py
示例10: triu_indices
def triu_indices(n, k=0, m=None):
"""
Return the indices for the upper-triangle of an (n, m) array.
Parameters
----------
n : int
The size of the arrays for which the returned indices will
be valid.
k : int, optional
Diagonal offset (see `triu` for details).
m : int, optional
.. versionadded:: 1.9.0
The column dimension of the arrays for which the returned
arrays will be valid.
By default `m` is taken equal to `n`.
Returns
-------
inds : tuple, shape(2) of ndarrays, shape(`n`)
The indices for the triangle. The returned tuple contains two arrays,
each with the indices along one dimension of the array. Can be used
to slice a ndarray of shape(`n`, `n`).
See also
--------
tril_indices : similar function, for lower-triangular.
mask_indices : generic function accepting an arbitrary mask function.
triu, tril
Notes
-----
.. versionadded:: 1.4.0
Examples
--------
Compute two different sets of indices to access 4x4 arrays, one for the
upper triangular part starting at the main diagonal, and one starting two
diagonals further right:
>>> iu1 = np.triu_indices(4)
>>> iu2 = np.triu_indices(4, 2)
Here is how they can be used with a sample array:
>>> a = np.arange(16).reshape(4, 4)
>>> a
array([[ 0, 1, 2, 3],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11],
[12, 13, 14, 15]])
Both for indexing:
>>> a[iu1]
array([ 0, 1, 2, 3, 5, 6, 7, 10, 11, 15])
And for assigning values:
>>> a[iu1] = -1
>>> a
array([[-1, -1, -1, -1],
[ 4, -1, -1, -1],
[ 8, 9, -1, -1],
[12, 13, 14, -1]])
These cover only a small part of the whole array (two diagonals right
of the main one):
>>> a[iu2] = -10
>>> a
array([[ -1, -1, -10, -10],
[ 4, -1, -1, -10],
[ 8, 9, -1, -1],
[ 12, 13, 14, -1]])
"""
return where(~tri(n, m, k=k - 1, dtype=bool))
开发者ID:noclew,项目名称:numpy,代码行数:80,代码来源:twodim_base.py
示例11: sinhc
def sinhc(x):
x = np.asanyarray(x)
y = where(x == 0, 1.0e-20, x)
return np.sinh(y)/y
开发者ID:bogfjellmo,项目名称:bsplinelab,代码行数:4,代码来源:__init__.py
示例12: histogramdd
#.........这里部分代码省略.........
nbin = empty(D, int)
edges = D*[None]
dedges = D*[None]
if weights is not None:
weights = asarray(weights)
try:
M = len(bins)
if M != D:
raise AttributeError, 'The dimension of bins must be a equal to the dimension of the sample x.'
except TypeError:
bins = D*[bins]
# Select range for each dimension
# Used only if number of bins is given.
if range is None:
smin = atleast_1d(array(sample.min(0), float))
smax = atleast_1d(array(sample.max(0), float))
else:
smin = zeros(D)
smax = zeros(D)
for i in arange(D):
smin[i], smax[i] = range[i]
# Make sure the bins have a finite width.
for i in arange(len(smin)):
if smin[i] == smax[i]:
smin[i] = smin[i] - .5
smax[i] = smax[i] + .5
# Create edge arrays
for i in arange(D):
if isscalar(bins[i]):
nbin[i] = bins[i] + 2 # +2 for outlier bins
edges[i] = linspace(smin[i], smax[i], nbin[i]-1)
else:
edges[i] = asarray(bins[i], float)
nbin[i] = len(edges[i])+1 # +1 for outlier bins
dedges[i] = diff(edges[i])
nbin = asarray(nbin)
# Compute the bin number each sample falls into.
Ncount = {}
for i in arange(D):
Ncount[i] = digitize(sample[:,i], edges[i])
# Using digitize, values that fall on an edge are put in the right bin.
# For the rightmost bin, we want values equal to the right
# edge to be counted in the last bin, and not as an outlier.
outliers = zeros(N, int)
for i in arange(D):
# Rounding precision
decimal = int(-log10(dedges[i].min())) +6
# Find which points are on the rightmost edge.
on_edge = where(around(sample[:,i], decimal) == around(edges[i][-1], decimal))[0]
# Shift these points one bin to the left.
Ncount[i][on_edge] -= 1
# Flattened histogram matrix (1D)
hist = zeros(nbin.prod(), float)
# Compute the sample indices in the flattened histogram matrix.
ni = nbin.argsort()
shape = []
xy = zeros(N, int)
for i in arange(0, D-1):
xy += Ncount[ni[i]] * nbin[ni[i+1:]].prod()
xy += Ncount[ni[-1]]
# Compute the number of repetitions in xy and assign it to the flattened histmat.
if len(xy) == 0:
return zeros(nbin-2, int), edges
flatcount = bincount(xy, weights)
a = arange(len(flatcount))
hist[a] = flatcount
# Shape into a proper matrix
hist = hist.reshape(sort(nbin))
for i in arange(nbin.size):
j = ni[i]
hist = hist.swapaxes(i,j)
ni[i],ni[j] = ni[j],ni[i]
# Remove outliers (indices 0 and -1 for each dimension).
core = D*[slice(1,-1)]
hist = hist[core]
# Normalize if normed is True
if normed:
s = hist.sum()
for i in arange(D):
shape = ones(D, int)
shape[i] = nbin[i]-2
hist = hist / dedges[i].reshape(shape)
hist /= s
return hist, edges
开发者ID:ruschecker,项目名称:DrugDiscovery-Home,代码行数:101,代码来源:function_base.py
示例13: sinc
def sinc(x):
"""sinc(x) returns sin(pi*x)/(pi*x) at all points of array x.
"""
y = pi* where(x == 0, 1.0e-20, x)
return sin(y)/y
开发者ID:ruschecker,项目名称:DrugDiscovery-Home,代码行数:5,代码来源:function_base.py
示例14: mask_indices
def mask_indices(n,mask_func,k=0):
"""Return the indices to access (n,n) arrays, given a masking function.
Assume mask_func() is a function that, for a square array a of size (n,n)
with a possible offset argument k, when called as mask_func(a,k) returns a
new array with zeros in certain locations (functions like triu() or tril()
do precisely this). Then this function returns the indices where the
non-zero values would be located.
Parameters
----------
n : int
The returned indices will be valid to access arrays of shape (n,n).
mask_func : callable
A function whose api is similar to that of numpy.tri{u,l}. That is,
mask_func(x,k) returns a boolean array, shaped like x. k is an optional
argument to the function.
k : scalar
An optional argument which is passed through to mask_func(). Functions
like tri{u,l} take a second argument that is interpreted as an offset.
Returns
-------
indices : an n-tuple of index arrays.
The indices corresponding to the locations where mask_func(ones((n,n)),k)
is True.
Notes
-----
.. versionadded:: 1.4.0
Examples
--------
These are the indices that would allow you to access the upper triangular
part of any 3x3 array:
>>> iu = mask_indices(3,np.triu)
For example, if `a` is a 3x3 array:
>>> a = np.arange(9).reshape(3,3)
>>> a
array([[0, 1, 2],
[3, 4, 5],
[6, 7, 8]])
Then:
>>> a[iu]
array([0, 1, 2, 4, 5, 8])
An offset can be passed also to the masking function. This gets us the
indices starting on the first diagonal right of the main one:
>>> iu1 = mask_indices(3,np.triu,1)
with which we now extract only three elements:
>>> a[iu1]
array([1, 2, 5])
"""
m = ones((n,n),int)
a = mask_func(m,k)
return where(a != 0)
开发者ID:GunioRobot,项目名称:numpy-refactor,代码行数:61,代码来源:twodim_base.py
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