Is there a way to sum over all values in a python dict except one by using a selector in
>>> x = dict(a=1, b=2, c=3)
>>> np.sum(x.values())
6
? My current solution is a loop based one:
>>> x = dict(a=1, b=2, c=3)
>>> y = 0
>>> for i in x:
... if 'a' != i:
... y += x[i]
...
>>> y
5
EDIT:
import numpy as np
from scipy.sparse import *
x = dict(a=csr_matrix(np.array([1,0,0,0,0,0,0,0,0]).reshape(3,3)), b=csr_matrix(np.array([0,0,0,0,0,0,0,0,1]).reshape(3,3)), c=csr_matrix(np.array([0,0,0,0,0,0,0,0,1]).reshape(3,3)))
y = csr_matrix((3,3))
for i in x:
if 'a' != i:
y = y + x[i]
print y
returns (2, 2) 2.0
and
print np.sum(value for key, value in x.iteritems() if key != 'a')
raises
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site- packages/numpy/core/fromnumeric.py", line 1446, in sum
res = _sum_(a)
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/scipy/sparse/compressed.py", line 187, in __radd__
return self.__add__(other)
File "/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/scipy/sparse/compressed.py", line 173, in __add__
raise NotImplementedError('adding a scalar to a CSC or CSR '
NotImplementedError: adding a scalar to a CSC or CSR matrix is not supported
你可以遍历dict为sum
方法创建一个生成器:
np.sum(value for key, value in x.iteritems() if key != 'a')
尝试:
np.sum(x.values()) - x['a']
You need to supply an accumulator or initial value for the sum
method:
sum((value for key, value in x.iteritems() if key != 'a'), csr_matrix((3, 3)))
Note that this is using the builtin sum
method. It's almost identical in effect to your loop-based solution.
Using np.sum
won't work because np.sum
doesn't pass the out
argument, and is anyway designed for dense matrices.
np.sum((value for key, value in x.iteritems() if key != 'a'),
out=csr_matrix((3, 3))) # doesn't work
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