我很难将XML数据解析为MATLAB结构。
使用现成的xml2struct函数，我就可以做到这一点。但是，最终节点的内容是char，我希望它是double、uint8或XML元素中声明的任何属性。
以XML数据为例：
<?xml version="1.0"?>
<catalog>
<book id="bk101" type="struct" size="1 1">
<genre>Computer</genre>
<price type="double">44.95</price>
<publish_date>2000-10-01</publish_date>
<description>An in-depth look at creating applications
with XML.</description>
</book>
<book id="bk102" type="struct" size="1 1">
<genre>Fantasy</genre>
<price type="number" size="1 1">112</price>
<publish_date>2000-12-16</publish_date>
<description>A former architect battles corporate zombies,
an evil sorceress, and her own childhood to become queen
of the world.</description>
</book>
</catalog>
我想写一个MATLAB代码，可以将上述数据解析为一个结构，但根据其属性，它的价格是直接在结构中将第一本书作为双数据类型，将第二本书作为uint8数据类型。
然而，当使用该函数直接解析XML数据时，我将获得catalog.book｛1，1｝.price。将值"44.95"用char表示。
直接使用MATLAB函数，可以检索xml的属性，但我对如何扩展xml2struct中的函数感到困惑，以便根据元素的属性转换数据类型内容，如价格。
有人能告诉我在哪里可以操作XML内容来更改函数中的数据类型吗我已经进行了一步一步的调试，只是想看看函数是如何工作的，但我似乎仍然找不到解决方案。。。
以下是完整的xml2struct函数代码：
function [ s ] = xml2struct( file )
%Convert xml file into a MATLAB structure
% [ s ] = xml2struct( file )
%
% A file containing:
% <XMLname attrib1="Some value">
% <Element>Some text</Element>
% <DifferentElement attrib2="2">Some more text</DifferentElement>
% <DifferentElement attrib3="2" attrib4="1">Even more text</DifferentElement>
% </XMLname>
%
% Will produce:
% s.XMLname.Attributes.attrib1 = "Some value";
% s.XMLname.Element.Text = "Some text";
% s.XMLname.DifferentElement{1}.Attributes.attrib2 = "2";
% s.XMLname.DifferentElement{1}.Text = "Some more text";
% s.XMLname.DifferentElement{2}.Attributes.attrib3 = "2";
% s.XMLname.DifferentElement{2}.Attributes.attrib4 = "1";
% s.XMLname.DifferentElement{2}.Text = "Even more text";
%
% Please note that the following characters are substituted
% '-' by '_dash_', ':' by '_colon_' and '.' by '_dot_'
%
% Written by W. Falkena, ASTI, TUDelft, 21-08-2010
% Attribute parsing speed increased by 40% by A. Wanner, 14-6-2011
% Added CDATA support by I. Smirnov, 20-3-2012
%
% Modified by X. Mo, University of Wisconsin, 12-5-2012
if (nargin < 1)
clc;
help xml2struct
return
end
if isa(file, 'org.apache.xerces.dom.DeferredDocumentImpl') || isa(file, 'org.apache.xerces.dom.DeferredElementImpl')
% input is a java xml object
xDoc = file;
else
%check for existance
if (exist(file,'file') == 0)
%Perhaps the xml extension was omitted from the file name. Add the
%extension and try again.
if (~contains(file,'.xml'))
file = [file '.xml'];
end
if (exist(file,'file') == 0)
error(['The file ' file ' could not be found']);
end
end
%read the xml file
xDoc = xmlread(file);
end
%parse xDoc into a MATLAB structure
s = parseChildNodes(xDoc);
end
% ----- Subfunction parseChildNodes -----
function [children,ptext,textflag] = parseChildNodes(theNode)
% Recurse over node children.
children = struct;
ptext = struct; textflag = 'Text';
if hasChildNodes(theNode)
childNodes = getChildNodes(theNode);
numChildNodes = getLength(childNodes);
for count = 1:numChildNodes
theChild = item(childNodes,count-1);
[text,name,attr,childs,textflag] = getNodeData(theChild);
%[text,name,childs,textflag] = getNodeData(theChild);
if (~strcmp(name,'#text') && ~strcmp(name,'#comment') && ~strcmp(name,'#cdata_dash_section'))
%XML allows the same elements to be defined multiple times,
%put each in a different cell
if (isfield(children,name))
if (~iscell(children.(name)))
%put existsing element into cell format
children.(name) = {children.(name)};
end
index = length(children.(name))+1;
%add new element
children.(name){index} = childs;
if(~isempty(fieldnames(text)))
children.(name){index} = text;
end
%if(~isempty(attr))
% children.(name){index}.('Attributes') = attr;
%end
else
%add previously unknown (new) element to the structure
children.(name) = childs;
if(~isempty(text) && ~isempty(fieldnames(text)))
children.(name) = text;
end
if(~isempty(attr))
children.(name).('Attributes') = attr;
end
end
else
ptextflag = 'Text_Me';
if (strcmp(name, '#cdata_dash_section'))
ptextflag = 'CDATA';
elseif (strcmp(name, '#comment'))
ptextflag = 'Comment';
end
%this is the text in an element (i.e., the parentNode)
if (~isempty(regexprep(text.(textflag),'[s]*','')))
if (~isfield(ptext,ptextflag) || isempty(ptext.(ptextflag)))
ptext.(ptextflag) = text.(textflag);
else
%what to do when element data is as follows:
%<element>Text <!--Comment--> More text</element>
%put the text in different cells:
% if (~iscell(ptext)) ptext = {ptext}; end
% ptext{length(ptext)+1} = text;
%just append the text
ptext.(ptextflag) = [ptext.(ptextflag) text.(textflag)];
end
end
end
end
end
end
% ----- Subfunction getNodeData -----
function [text,name,attr,childs,textflag] = getNodeData(theNode)
% Create structure of node info.
%make sure name is allowed as structure name
name = toCharArray(getNodeName(theNode))';
% name = strrep(name, '-', '_dash_');
% name = strrep(name, ':', '_colon_');
% name = strrep(name, '.', '_dot_');
attr = parseAttributes(theNode);
if (isempty(fieldnames(attr)))
attr = [];
end
%parse child nodes
[childs,text,textflag] = parseChildNodes(theNode);
if (isempty(fieldnames(childs)) && isempty(fieldnames(text)))
%get the data of any childless nodes
% faster than if any(strcmp(methods(theNode), 'getData'))
% no need to try-catch (?)
% faster than text = char(getData(theNode));
text.(textflag) = toCharArray(getTextContent(theNode))';
end
end
% ----- Subfunction parseAttributes -----
function attributes = parseAttributes(theNode)
% Create attributes structure.
attributes = struct;
if hasAttributes(theNode)
theAttributes = getAttributes(theNode);
numAttributes = getLength(theAttributes);
for count = 1:numAttributes
% attrib = item(theAttributes,count-1);
% attr_name = regexprep(char(getName(attrib)),'[-:.]','_');
% attributes.(attr_name) = char(getValue(attrib));
%Suggestion of Adrian Wanner
str = toCharArray(toString(item(theAttributes,count-1)))';
k = strfind(str,'=');
attr_name = str(1:(k(1)-1));
% attr_name = strrep(attr_name, '-', '_dash_');
% attr_name = strrep(attr_name, ':', '_colon_');
% attr_name = strrep(attr_name, '.', '_dot_');
attributes.(attr_name) = str((k(1)+2):(end-1));
end
end
end
编辑：我找到了答案。要更改属性，我们应该在getNodeData子函数中添加apply更改。特别是在调用中的parseChildNode之后添加这个条件块。
%parse child nodes
[childs,text,textflag] = parseChildNodes(theNode);
if isfield(attr, 'type')
switch attr.type
case 'double'
text.(textflag) = str2double(strsplit(text.(textflag)));
case 'int'
text.(textflag) = str2number(strsplit(text.(textflag)));
end
end
我认为您需要根据价格的Attributes.type值转换数据类型。
下面是一个带有xml2struct的示例代码。它检查每个价格属性的Attributes.type字段，并根据类型("number"或"double"(转换数据类型。默认情况下，MATLAB将数值视为double，因此通过使用str2double进行转换，价格112将被视为double。我认为double可以，但如果你想把它当作uint8，请使用uint8(str2double(price.Text((。
xmlhandler = xml2struct('yourXmlFile.xml');
books = xmlhandler.catalog.book;
for ii=1:size(books, 2)
eachBook = books{1, ii};
price = eachBook.price;
if isfield(price.Attributes, 'type')
dataType = price.Attributes.type;
% Add Value property depending on the data type
switch dataType
case 'number'
books{1, ii}.price.Value = uint8(str2double(price.Text));
%eachBook.price.Value = str2double(price.Text); % If double is fine
case 'double'
books{1, ii}.price.Value = str2double(price.Text);
otherwise
% Do something if type is not specified
end
end
end
上面的示例代码在价格中添加了Value属性，但只是替换了Text属性，请像books{1, ii}.price.Text = str2double(price.Text)一样。