我已经阅读了很多有关共享数组的问题,对于简单的数组来说这似乎很简单,但我仍然试图让它适用于我拥有的数组。
import numpy as np
data=np.zeros(250,dtype='float32, (250000,2)float32')
我尝试以某种方式将其转换为共享数组 mp.Array
接受 data
,我也尝试使用ctypes创建数组:
import multiprocessing as mp
data=mp.Array('c_float, (250000)c_float',250)
我设法使代码工作的唯一方法是不将数据传递给函数,而是将编码的字符串传递给未压缩/解码,但这最终会导致被调用的n(字符串数)进程看起来多余。我希望的实现基于将二进制字符串列表切片为x(进程数)并传递此块, data
和 index
除了那之外的工作过程 data
在本地修改,因此问题 如何分享任何使用自定义(嵌套)numpy数组的例子都会有很大的帮助。
PS:这个问题是跟进来的 Python多处理
请注意,您可以从一个复杂的dtype数组开始:
In [4]: data = np.zeros(250,dtype='float32, (250000,2)float32')
并将其视为同源dtype数组:
In [5]: data2 = data.view('float32')
然后,将其转换回复杂的dtype:
In [7]: data3 = data2.view('float32, (250000,2)float32')
更改dtype是一种非常快速的操作;它不会影响基础数据,只会影响NumPy解释它的方式。所以改变dtype几乎是无成本的。
因此,您所读到的关于具有简单(同质)dtypes的数组的内容可以通过上述技巧轻松应用于复杂的dtype。
下面的代码借鉴了许多想法 J.F.塞巴斯蒂安的回答,在这里。
import numpy as np
import multiprocessing as mp
import contextlib
import ctypes
import struct
import base64
def decode(arg):
chunk, counter = arg
print len(chunk), counter
for x in chunk:
peak_counter = 0
data_buff = base64.b64decode(x)
buff_size = len(data_buff) / 4
unpack_format = ">%dL" % buff_size
index = 0
for y in struct.unpack(unpack_format, data_buff):
buff1 = struct.pack("I", y)
buff2 = struct.unpack("f", buff1)[0]
with shared_arr.get_lock():
data = tonumpyarray(shared_arr).view(
[('f0', '<f4'), ('f1', '<f4', (250000, 2))])
if (index % 2 == 0):
data[counter][1][peak_counter][0] = float(buff2)
else:
data[counter][1][peak_counter][1] = float(buff2)
peak_counter += 1
index += 1
counter += 1
def pool_init(shared_arr_):
global shared_arr
shared_arr = shared_arr_ # must be inherited, not passed as an argument
def tonumpyarray(mp_arr):
return np.frombuffer(mp_arr.get_obj())
def numpy_array(shared_arr, peaks):
"""Fills the NumPy array 'data' with m/z-intensity values acquired
from b64 decoding and unpacking the binary string read from the
mzXML file, which is stored in the list 'peaks'.
The m/z values are assumed to be ordered without validating this
assumption.
Note: This function uses multi-processing
"""
processors = mp.cpu_count()
with contextlib.closing(mp.Pool(processes=processors,
initializer=pool_init,
initargs=(shared_arr, ))) as pool:
chunk_size = int(len(peaks) / processors)
map_parameters = []
for i in range(processors):
counter = i * chunk_size
# WARNING: I removed -1 from (i + 1)*chunk_size, since the right
# index is non-inclusive.
chunk = peaks[i*chunk_size : (i + 1)*chunk_size]
map_parameters.append((chunk, counter))
pool.map(decode, map_parameters)
if __name__ == '__main__':
shared_arr = mp.Array(ctypes.c_float, (250000 * 2 * 250) + 250)
peaks = ...
numpy_array(shared_arr, peaks)
如果可以保证执行分配的各种进程
if (index % 2 == 0):
data[counter][1][peak_counter][0] = float(buff2)
else:
data[counter][1][peak_counter][1] = float(buff2)
永远不会竞争改变相同位置的数据,那么我相信你实际上可以放弃使用锁
with shared_arr.get_lock():
但是我不能很好地理解你的代码以确保,所以为了安全起见,我把锁包括在内。
from multiprocessing import Process, Array
import numpy as np
import time
import ctypes
def fun(a):
a[0] = -a[0]
while 1:
time.sleep(2)
#print bytearray(a.get_obj())
c=np.frombuffer(a.get_obj(),dtype=np.float32)
c.shape=3,3
print 'haha',c
def main():
a = np.random.rand(3,3).astype(np.float32)
a.shape=1*a.size
#a=np.array([[1,3,4],[4,5,6]])
#b=bytearray(a)
h=Array(ctypes.c_float,a)
print "Originally,",h
# Create, start, and finish the child process
p = Process(target=fun, args=(h,))
p.start()
#p.join()
a.shape=3,3
# Print out the changed values
print 'first',a
time.sleep(3)
#h[0]=h[0]+1
print 'main',np.frombuffer(h.get_obj(), dtype=np.float32)
if __name__=="__main__":
main()