我有一个3GB的CSV文件,想用Python读取,并需要按列计算中位数。
from numpy import *
def data():
return genfromtxt('All.csv',delimiter=',')
data = data() # This is where it fails already.
med = zeros(len(data[0]))
data = data.T
for i in xrange(len(data)):
m = median(data[i])
med[i] = 1.0/float(m)
print med
我得到的错误是这样的:
Python(1545) malloc: *** mmap(size=16777216) failed (error code=12)
*** error: can't allocate region
*** set a breakpoint in malloc_error_break to debug
Traceback (most recent call last):
File "Normalize.py", line 40, in <module>
data = data()
File "Normalize.py", line 39, in data
return genfromtxt('All.csv',delimiter=',')
File "/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-
packages/numpy/lib/npyio.py", line 1495, in genfromtxt
for (i, line) in enumerate(itertools.chain([first_line, ], fhd)):
MemoryError
我认为这只是一个内存不足的错误。我正在运行64位的MacOSX,具有4GB的内存,并且numpy和Python都以64位模式编译。
我该如何解决这个问题?我应该尝试分布式处理来管理内存吗?
谢谢。
编辑:我也尝试了这个方法,但没有成功...
genfromtxt('All.csv',delimiter=',', dtype=float16)