Python列表转换为XML,反之亦然 [英] Python list to XML and vice versa
问题描述
我编写了一些python代码,用于将python列表转换为XML元素.它是用于与LabVIEW交互的,因此是怪异的XML数组格式.无论如何,这是代码:
I have some python code that I wrote to convert a python list into an XML element. It's meant for interacting with LabVIEW, hence the weird XML array format. Anyways, here's the code:
def pack(data):
# create the result element
result = xml.Element("Array")
# report the dimensions
ref = data
while isinstance(ref, list):
xml.SubElement(result, "Dimsize").text = str(len(ref))
ref = ref[0]
# flatten the data
while isinstance(data[0], list):
data = sum(data, [])
# pack the data
for d in data:
result.append(pack_simple(d))
# return the result
return result
现在,我需要编写一个unpack()方法,将打包的XML数组转换回python列表.我可以很好地提取数组维度和数据:
Now I need to write an unpack() method to convert the packed XML Array back into a python list. I can extract the array dimensions and data just fine:
def unpack(element):
# retrieve the array dimensions and data
lengths = []
data = []
for entry in element:
if entry.text == "Dimsize":
lengths.append(int(entry.text))
else:
data.append(unpack_simple(entry))
# now what?
但是我不确定如何展开数组.一种有效的方法是什么?
But I am not sure how to unflatten the array. What would be an efficient way to do that?
这是python列表和相应XML的外观.注意:数组是n维的.
Here's what the python list and corresponding XML looks like. Note: the arrays are n-dimensional.
data = [[[1, 2], [3, 4]], [[5, 6], [7, 8]]]
然后是XML版本:
<Array>
<Dimsize>2</Dimsize>
<Dimsize>2</Dimsize>
<Dimsize>2</Dimsize>
<I32>
<Name />
<Val>1</Val>
</I32>
... 2, 3, 4, etc.
</Array>
实际的格式并不重要,我只是不知道如何展开以下列表:
The actual format isn't important though, I just don't know how to unflatten the list from:
data = [1, 2, 3, 4, 5, 6, 7, 8]
返回至:
data = [[[1, 2], [3, 4]], [[5, 6], [7, 8]]]
给定:
lengths = [2, 2, 2]
对于基本数据类型(int,long,string,boolean),假设pack_simple()和unpack_simple()与pack()和unpack()相同.
Assume pack_simple() and unpack_simple() do the same as pack() and unpack() for the basic data types (int, long, string, boolean).
推荐答案
尝试以下操作:
from operator import mul
def validate(array, sizes):
if reduce(mul, sizes) != len(array):
raise ValueError("Array dimension incompatible with desired sizes")
return array, sizes
def reshape(array, sizes):
for s in sizes:
array = [array[i:i + s] for i in range(0, len(array), s)]
return array[0]
data = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]
length = [2, 2, 3]
print reshape(validate(data, length))
length = [2, 2, 2]
print reshape(validate(data, length))
输出为:
[[[1, 2], [3, 4]], [[5, 6], [7, 8]], [[9, 10], [11, 12]]]
Traceback:
(...)
ValueError: Array dimension incompatible with desired sizes
一种替代方法是使用numpy
数组.请注意,对于这个简单的任务,numpy是一个相当大的依赖项,尽管您会发现大多数(常见)与数组相关的任务/问题已经在此处实现:
An alternative is using numpy
arrays. Note that for this simple task, numpy is a rather big dependency, though you will find that most (common) array related tasks/problems already have an implementation there:
from numpy import array
print array(data).reshape(*length) # optionally add .tolist() to convert to list
编辑:添加了数据验证
编辑:使用numpy数组的示例(感谢J.F. Sebastian的提示)
EDIT: Example using numpy arrays (thanks to J.F.Sebastian for the hint)
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