Python 使用 numpy.load 从文件加载压缩数据 (.npz)
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Load compressed data (.npz) from file using numpy.load
提问by atomh33ls
I have an array:
我有一个数组：
>>> data = np.ones((1,3,128))
I save it to file using savez_compressed:
我使用savez_compressed以下命令将其保存到文件中：
>>> with open('afile','w') as f:
np.savez_compressed(f,data=data)
When I try to load it I don't seem to be able to access the data:
当我尝试加载它时，我似乎无法访问数据：
>>> with open('afile','r') as f:
b=np.load(f)
>>> b.files
['data']
>>> b['data']
Traceback (most recent call last):
File "<pyshell#196>", line 1, in <module>
b['data']
File "C:\Python27\lib\site-packages\numpy\lib\npyio.py", line 238, in __getitem__
bytes = self.zip.read(key)
File "C:\Python27\lib\zipfile.py", line 828, in read
return self.open(name, "r", pwd).read()
File "C:\Python27\lib\zipfile.py", line 853, in open
zef_file.seek(zinfo.header_offset, 0)
ValueError: I/O operation on closed file
Am I doing something obviously wrong?
我做错了什么吗？
EDIT
编辑
Following @Saullo Castro's answer I tried this:
按照@Saullo Castro 的回答，我尝试了这个：
>>> np.savez_compressed('afile.npz',data=data)
>>> b=np.load('afile.npz')
>>> b.files
['data']
>>> b['data']
and got the following error:
并得到以下错误：
Traceback (most recent call last):
File "<pyshell#253>", line 1, in <module>
b['data']
File "C:\Python27\lib\site-packages\numpy\lib\npyio.py", line 241, in __getitem__
return format.read_array(value)
File "C:\Python27\lib\site-packages\numpy\lib\format.py", line 440, in read_array
shape, fortran_order, dtype = read_array_header_1_0(fp)
File "C:\Python27\lib\site-packages\numpy\lib\format.py", line 336, in read_array_header_1_0
d = safe_eval(header)
File "C:\Python27\lib\site-packages\numpy\lib\utils.py", line 1156, in safe_eval
ast = compiler.parse(source, mode="eval")
File "C:\Python27\lib\compiler\transformer.py", line 53, in parse
return Transformer().parseexpr(buf)
File "C:\Python27\lib\compiler\transformer.py", line 132, in parseexpr
return self.transform(parser.expr(text))
File "C:\Python27\lib\compiler\transformer.py", line 124, in transform
return self.compile_node(tree)
File "C:\Python27\lib\compiler\transformer.py", line 159, in compile_node
return self.eval_input(node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 194, in eval_input
return Expression(self.com_node(nodelist[0]))
File "C:\Python27\lib\compiler\transformer.py", line 805, in com_node
return self._dispatch[node[0]](node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 578, in testlist
return self.com_binary(Tuple, nodelist)
File "C:\Python27\lib\compiler\transformer.py", line 1082, in com_binary
return self.lookup_node(n)(n[1:])
File "C:\Python27\lib\compiler\transformer.py", line 596, in test
then = self.com_node(nodelist[0])
File "C:\Python27\lib\compiler\transformer.py", line 805, in com_node
return self._dispatch[node[0]](node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 610, in or_test
return self.com_binary(Or, nodelist)
File "C:\Python27\lib\compiler\transformer.py", line 1082, in com_binary
return self.lookup_node(n)(n[1:])
File "C:\Python27\lib\compiler\transformer.py", line 615, in and_test
return self.com_binary(And, nodelist)
File "C:\Python27\lib\compiler\transformer.py", line 1082, in com_binary
return self.lookup_node(n)(n[1:])
File "C:\Python27\lib\compiler\transformer.py", line 619, in not_test
result = self.com_node(nodelist[-1])
File "C:\Python27\lib\compiler\transformer.py", line 805, in com_node
return self._dispatch[node[0]](node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 626, in comparison
node = self.com_node(nodelist[0])
File "C:\Python27\lib\compiler\transformer.py", line 805, in com_node
return self._dispatch[node[0]](node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 659, in expr
return self.com_binary(Bitor, nodelist)
File "C:\Python27\lib\compiler\transformer.py", line 1082, in com_binary
return self.lookup_node(n)(n[1:])
File "C:\Python27\lib\compiler\transformer.py", line 663, in xor_expr
return self.com_binary(Bitxor, nodelist)
File "C:\Python27\lib\compiler\transformer.py", line 1082, in com_binary
return self.lookup_node(n)(n[1:])
File "C:\Python27\lib\compiler\transformer.py", line 667, in and_expr
return self.com_binary(Bitand, nodelist)
File "C:\Python27\lib\compiler\transformer.py", line 1082, in com_binary
return self.lookup_node(n)(n[1:])
File "C:\Python27\lib\compiler\transformer.py", line 671, in shift_expr
node = self.com_node(nodelist[0])
File "C:\Python27\lib\compiler\transformer.py", line 805, in com_node
return self._dispatch[node[0]](node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 683, in arith_expr
node = self.com_node(nodelist[0])
File "C:\Python27\lib\compiler\transformer.py", line 805, in com_node
return self._dispatch[node[0]](node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 695, in term
node = self.com_node(nodelist[0])
File "C:\Python27\lib\compiler\transformer.py", line 805, in com_node
return self._dispatch[node[0]](node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 715, in factor
node = self.lookup_node(nodelist[-1])(nodelist[-1][1:])
File "C:\Python27\lib\compiler\transformer.py", line 727, in power
node = self.com_node(nodelist[0])
File "C:\Python27\lib\compiler\transformer.py", line 805, in com_node
return self._dispatch[node[0]](node[1:])
File "C:\Python27\lib\compiler\transformer.py", line 739, in atom
return self._atom_dispatch[nodelist[0][0]](nodelist)
File "C:\Python27\lib\compiler\transformer.py", line 754, in atom_lbrace
return self.com_dictorsetmaker(nodelist[1])
File "C:\Python27\lib\compiler\transformer.py", line 1214, in com_dictorsetmaker
assert nodelist[0] == symbol.dictorsetmaker
AssertionError
EDIT 2
编辑 2
The above error was in IDLE. It worked using Ipython.
上面的错误是在空闲状态。它使用 Ipython 工作。
采纳答案by Saullo G. P. Castro
When using numpy.loadyou can pass the file name, and if the extension is .npz, it will first descompress:
使用时numpy.load您可以通过文件名，如果扩展是.npz，它会先descompress：
np.savez_compressed('filename.npz', array1=array1, array2=array2)
b = np.load('filename.npz')
and do b['array1']and so forth to retrieve the data from each array...
并执行b['array1']等等以从每个数组中检索数据...
回答by Paul Evans
Try opening the file as binary:
尝试以二进制形式打开文件：
with open('afile','rb') as f:
回答by NineSPRing
I do have the same problem(AssertionError) when using numpy 1.7.1/1.8.0 with python 2.7.6 both on MAC OS and Windows. But the problem was automatically fixed after I switch to linux with python 2.7.5. Then I reinstall python 2.7.5 on MACOS and Windows and all the problem was gone. Basically the problem is with python instead of numpy as the compiler is sending alert.So mightly the version matters.
在 MAC OS 和 Windows 上使用 numpy 1.7.1/1.8.0 和 python 2.7.6 时，我确实遇到了同样的问题（AssertionError）。但是在我用python 2.7.5切换到linux后问题自动修复。然后我在 MACOS 和 Windows 上重新安装了 python 2.7.5，所有问题都消失了。基本上问题在于python而不是numpy，因为编译器正在发送警报。所以版本可能很重要。
But though npy is the serializable type of numpy, I don't think the file is small enough even with savez_compressed for large matrix.
但是，尽管 npy 是 numpy 的可序列化类型，但我认为即使将 savez_compressed 用于大矩阵，文件也不够小。
Hopefully your problem is the same with mine
希望你的问题和我的一样
回答by mrk
You can also use the
fattribute, which leaves you with anp.ndarray:
您还可以使用该
f属性，它会给您留下一个np.ndarray：
images = np.load('images.npz')
images = images.f.arr_0
The name/key of the array inside the .npz-file (e.g. arr_0) can be found through
arr_0可以通过以下方式找到.npz 文件（例如）中数组的名称/键
images.keys()
Note: The fattribute is not documented in the docstring of load. When load reads an npzfile, it returns an instance of the class NpzFile. This class is available as numpy.lib.npyio.NpzFile. The docstring of the NpzFileclass describes the fattribute. (As of this writing, the source code of the class can be found here.
注意：该f属性未记录在 load 的文档字符串中。当 load 读取一个npz文件时，它返回一个class NpzFile. 此类可作为numpy.lib.npyio.NpzFile. NpzFile类的文档字符串描述了f属性。（在撰写本文时，可以在此处找到该类的源代码。
