这是我遇到的问题的示例代码：
import numba, numpy as np
@numba.jit
def f_plain(x):
return x * (x - 1)
@numba.jit
def integrate_f_numba(a, b, N):
s = 0
dx = (b - a) / N
for i in range(N):
s += f_plain(a + i * dx)
return s * dx
@numba.jit
def apply_integrate_f_numba(col_a, col_b, col_N):
n = len(col_N)
result = np.empty(n, dtype='float64')
assert len(col_a) == len(col_b) == n
for i in range(n):
result[i] = integrate_f_numba(col_a[i], col_b[i], col_N[i])
new = result
#return result
del result
def compute_numba(df):
result = apply_integrate_f_numba(df['a'].values, df['b'].values, df['N'].values)
return Series(result, index=df.index, name='result')
使用以下命令运行它：
import pandas as pd
from pandas import DataFrame, Series
from numpy.random import randn, randint
import numpy as np
df = DataFrame({'a': randn(1000), 'b': randn(1000),'N': randint(100, 1000, (1000)), 'x': 'x'})
%timeit compute_numba(df)
但是当我得到＆＃39; del结果时，我会收到此错误。在＆＃39; apply_integrate_f_numba＆＃39;功能：
---------------------------------------------------------------------------
NotImplementedError Traceback (most recent call last)
<ipython-input-31-6c46b74dae81> in <module>()
8
9 df = DataFrame({'a': randn(1000), 'b': randn(1000),'N': randint(100, 1000, (1000)), 'x': 'x'})
---> 10 get_ipython().magic(u'timeit compute_numba(df)')
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\IPython\core\interactiveshell.pyc in magic(self, arg_s)
2203 magic_name, _, magic_arg_s = arg_s.partition(' ')
2204 magic_name = magic_name.lstrip(prefilter.ESC_MAGIC)
-> 2205 return self.run_line_magic(magic_name, magic_arg_s)
2206
2207 #-------------------------------------------------------------------------
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\IPython\core\interactiveshell.pyc in run_line_magic(self, magic_name, line)
2124 kwargs['local_ns'] = sys._getframe(stack_depth).f_locals
2125 with self.builtin_trap:
-> 2126 result = fn(*args,**kwargs)
2127 return result
2128
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\IPython\core\magics\execution.pyc in timeit(self, line, cell)
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\IPython\core\magic.pyc in <lambda>(f, *a, **k)
191 # but it's overkill for just that one bit of state.
192 def magic_deco(arg):
--> 193 call = lambda f, *a, **k: f(*a, **k)
194
195 if callable(arg):
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\IPython\core\magics\execution.pyc in timeit(self, line, cell)
1011 number = 1
1012 for _ in range(1, 10):
-> 1013 if timer.timeit(number) >= 0.2:
1014 break
1015 number *= 10
C:\Program Files\Python\python-2.7.9.amd64\lib\timeit.pyc in timeit(self, number)
193 gc.disable()
194 try:
--> 195 timing = self.inner(it, self.timer)
196 finally:
197 if gcold:
<magic-timeit> in inner(_it, _timer)
<ipython-input-30-f288c9b5ebe9> in compute_numba(df)
25
26 def compute_numba(df):
---> 27 result = apply_integrate_f_numba(df['a'].values, df['b'].values, df['N'].values)
28 return Series(result, index=df.index, name='result')
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\numba\dispatcher.pyc in _compile_for_args(self, *args, **kws)
151 assert not kws
152 sig = tuple([self.typeof_pyval(a) for a in args])
--> 153 return self.jit(sig)
154
155 def inspect_types(self, file=None):
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\numba\dispatcher.pyc in jit(self, sig, **kws)
142 """Alias of compile(sig, **kws)
143 """
--> 144 return self.compile(sig, **kws)
145
146 def _compile_for_args(self, *args, **kws):
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\numba\dispatcher.pyc in compile(self, sig, locals, **targetoptions)
277 self.py_func,
278 args=args, return_type=return_type,
--> 279 flags=flags, locals=locs)
280
281 # Check typing error if object mode is used
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\numba\compiler.pyc in compile_extra(typingctx, targetctx, func, args, return_type, flags, locals, library)
550 pipeline = Pipeline(typingctx, targetctx, library,
551 args, return_type, flags, locals)
--> 552 return pipeline.compile_extra(func)
553
554
C:\Program Files\Python\python-2.7.9.amd64\lib\site-packages\numba\compiler.pyc in compile_extra(self, func)
265 return self.stage_compile_interp_mode()
266 else:
--> 267 raise res.exception
268
269 def compile_bytecode(self, bc, lifted=(),
NotImplementedError: offset=142 opcode=0x7e opname=DELETE_FAST
不确定现在该怎么办？我需要那个del命令，就像我原来的代码一样，我需要释放一些内存，因为我正处理大量的数据集。
答案 0 :(得分：2)
当numba即时编译器（jit）尝试编译此函数时出现问题（NB编辑为我认为OP意图围绕del）
@numba.jit
def apply_integrate_f_numba(col_a, col_b, col_N):
n = len(col_N)
result = np.empty(n, dtype='float64')
assert len(col_a) == len(col_b) == n
for i in range(n):
result[i] = integrate_f_numba(col_a[i], col_b[i], col_N[i])
new_res = result
del result
return new_res
具体而言 - 问题在于
行del result
JIT实际上是在告诉您错误消息中的问题：
NotImplementedError: offset=142 opcode=0x7e opname=DELETE_FAST
即。 numba编译器还没有实现编译DELETE_FAST python操作码的方法。如果您对代码感兴趣 - 它看起来像是thrown from here，并且该文件包含numba可以处理的字节码列表。
你会注意到，我确定，如果你只是从result返回apply_integrate_f_numba，一切正常，你可以在不使用{{{{{{ 1}}（假设您将另一个函数保留为numba.jit注释。
我认为您可能正试图通过@numba.jit声明来实现不可能实现的目标。 This answer to a more general question解释了del的作用 - 它删除了对象的绑定（引用）。您似乎试图通过删除刚刚指定了其他名称的对象（即del）来释放内存。所以 - 你的代码实际上不会释放内存，因为它仍然是对它的引用，你需要返回它。请注意，退出函数时，无论如何都会删除对象的所有本地引用，new是result函数的本地引用 - 因此apply_integrate_f_numba实际上是多余的。
如果你有一个如此大的数据集，那么记忆就是一个问题，你可以在完成它之后del - 例如一旦你把它写到文件，绘制它或你想用它做任何其他事情。只需为其分配另一个名称并del原始版本就不会这样做 - 增加了负面影响，您将收到此del错误。