blocks|key|2421733|text|短版|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|2421734|MATLAB代码应该是这样编写的：|2421735|function+[kf,+Ek]=hysime(y,+n,+Rn,+verbose);
++++error(nargchk(3,+4,+nargin))
++++if+nargin+<+4
++++++++verbose+=+true;
++++else
++++++++verbose+=+~strcmpi(verbose+,'off');
++++end|code-block|syntax|javascript|2421736|如果你了解MATLAB，这应该会更清楚。(大部分)对应的Python代码可以写成这样：|2421737|def+hysime(y,+n,+Rn,+verbose=True):
++++#+rest+of+the+function+here
++++return+kf,+Ek|2421738|长版本|2421739|此函数需要3个或4个输入参数，如果没有提供第四个参数，则会设置默认值。然而，它是以一种比它需要的方式复杂得多的方式完成的(尽管我经常看到这种模式)。理想情况下，在MATLAB中，您应该指定相同的内容，如下所示：|2421740|function+[varargout]=hysime(y,+n,+Rn,+verbose)
++++error(nargchk(3,+4,+nargin))
++++if+nargin+<+4
++++++++verbose+=+true;
++++else
++++++++verbose+=+~strcmpi(verbose+,'off');
++++end|2421741|因此，它所做的是将第一个参数放入变量y，将第二个参数放入变量n，将第三个参数放入Rn，如果指定了第四个参数，则将其放入verbose+(基于它与字符串'off'的比较)，否则将verbose设置为true。|CODE|2421742|在python中，可选参数的处理是内置的。您可以通过设置name=value来为函数定义中的参数指定默认值，其中name是参数名称，value是默认值。此外，由于历史原因，MATLAB经常使用'on'和'off'而不是true和false。在Python语言中几乎不会这样做，人们只使用True和False。因此，您可以在Python中指定相同的内容，如下所示：|2421743|def+hysime(y,+n,+Rn,+verbose=True):|2421744|这使得y、n和Rn参数是必需的，但verbose是可选的。|2421745|这不能处理将verbose设置为字符串'off'的情况。正如我所说的，由于历史原因，这在MATLAB中很常见，但当您可以避免它时，您真的不应该再在MATLAB中这样做了，而且您绝对不应该在Python中这样做。但是如果你真的真的需要处理这种情况，你可以这样做：|2421746|def+hysime(y,+n,+Rn,+verbose=True):
++++if+isinstance(verbose,+str):
++++++++verbose+=+verbose.lower()+!=+'off'|2421747|对于输出，MATLAB代码的作用是让函数返回一个或两个值。所以有人可以这样做：|2421748|kf+=+hysime(y,+n,+Rn);|2421749|或|2421750|[kf,+Ek]+=+hysime(y,+n,+Rn);|2421751|然而，这也是以一种比必要的更复杂的方式来完成的。如果只返回两个值，并且只使用一个返回值，则MATLAB将丢弃其余的返回值。因此，该函数可以只返回[kf,+Ek]，而不是在MATLAB上胡乱操作，MATLAB也会做同样的事情。如果有人尝试调用具有2个以上输出的函数，则会自动出现错误，因此这也是不必要的。|2421752|只有当您希望程序根据输出的数量改变其行为时，才需要以这种方式处理varargout。在这种结构中，你这样做的主要原因是如果eK的计算成本很高，在这种情况下，你会这样做：|2421753|varargout(1)+=+{kf};
if+nargout+==+2
++++#+calculate+eK+here
++++varargout(2)+=+{Ek};
end|2421754|至于return，只有在MATLAB中，如果你想使函数在正常到达结束之前提前停止，才需要它。一旦它正常到达末尾，它将自动return。因此，如果您指定的最后一段代码是函数的末尾，那么return就是多余的。|2421755|因此，您在MATLAB中显示的所有代码都可以简化为：|2421756|function+[kf,+Ek]=hysime(y,+n,+Rn,+verbose);
++++error(nargchk(3,+4,+nargin))
++++if+nargin+<+4
++++++++verbose+=+true;
++++else
++++++++verbose+=+~strcmpi(verbose+,'off');
++++end|2421757|至于Python，正如我在other+answer+to+you中提到的，Python需要处理所有返回值。除非您显式地告诉它，否则它永远不会抛出返回值。在您的例子中，最简单的解决方案就是在函数的末尾使用return+kf,+Ek。如果有人同时想要kf和Ek，他们可以这样做：|2421758|kf,+Ek+=+hysime(y,+n,+Rn)|2421759|如果他们只想要kf，他们可以这样做(其中_是您不关心的变量的python约定)：|2421760|kf,+_+=+hysime(y,+n,+Rn)|2421761|或者：|2421762|kf+=+hysime(y,+n,+Rn)[0]|2421763|所以python代码应该是：|2421764|def+hysime(y,+n,+Rn,+verbose=True):
++++#+rest+of+the+function+here
++++return+kf,+Ek|2421765|如果您真的希望能够有一个或两个返回值，则需要使用另一个参数来更改行为。例如：|2421766|def+hysime(y,+n,+Rn,+verbose=True,+ret_eK=False):
++++#+rest+of+the+function+here
++++return+(kf,+Ek)+if+ret_eK+else+kf|2421767|因此，在本例中，如果指定了ret_eK参数并将其设置为True，则返回kf,+Ek，否则仅返回kf。但是在Python中，您并不想这样做，除非有一些主要的额外成本来计算Ek，在本例中似乎不是这样。|2421768|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/51407867/3604159^0|0|2|0|0|0|0|0|0|3|0|0|0|I|1|U|1|14|2|1N|7|23|5|2G|7|2Q|4|0|S|A|1K|4|1U|5|2O|4|2T|5|31|4|36|5|3Z|4|44|5|0|0|3|1|5|1|7|2|H|7|0|6|7|J|5|0|0|0|0|0|0|20|8|0|W|9|1P|2|0|0|2|6|1O|6|2J|6|0|0|0|2T|D|3F|2|3I|2|D|J|0|0|0|7|2|K|1|0|0|0|0|0|0|0|0|D|6|R|4|Z|6|1B|2|2C|2|0^^$0|@$1|2|3|4|5|6|7|2N|8|@$9|2O|A|2P|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|2Q|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|2R|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|2S|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|2T|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|2U|8|@$9|2V|A|2W|B|C]]|D|@]|E|$]]|$1|S|3|T|5|6|7|2X|8|@]|D|@]|E|$]]|$1|U|3|V|5|J|7|2Y|8|@]|D|@]|E|$K|L]]|$1|W|3|X|5|6|7|2Z|8|@$9|30|A|31|B|Y]|$9|32|A|33|B|Y]|$9|34|A|35|B|Y]|$9|36|A|37|B|Y]|$9|38|A|39|B|Y]|$9|3A|A|3B|B|Y]|$9|3C|A|3D|B|Y]]|D|@]|E|$]]|$1|Z|3|10|5|6|7|3E|8|@$9|3F|A|3G|B|Y]|$9|3H|A|3I|B|Y]|$9|3J|A|3K|B|Y]|$9|3L|A|3M|B|Y]|$9|3N|A|3O|B|Y]|$9|3P|A|3Q|B|Y]|$9|3R|A|3S|B|Y]|$9|3T|A|3U|B|Y]|$9|3V|A|3W|B|Y]]|D|@]|E|$]]|$1|11|3|12|5|J|7|3X|8|@]|D|@]|E|$K|L]]|$1|13|3|14|5|6|7|3Y|8|@$9|3Z|A|40|B|Y]|$9|41|A|42|B|Y]|$9|43|A|44|B|Y]|$9|45|A|46|B|Y]]|D|@]|E|$]]|$1|15|3|16|5|6|7|47|8|@$9|48|A|49|B|Y]|$9|4A|A|4B|B|Y]]|D|@]|E|$]]|$1|17|3|18|5|J|7|4C|8|@]|D|@]|E|$K|L]]|$1|19|3|1A|5|6|7|4D|8|@]|D|@]|E|$]]|$1|1B|3|1C|5|J|7|4E|8|@]|D|@]|E|$K|L]]|$1|1D|3|1E|5|6|7|4F|8|@]|D|@]|E|$]]|$1|1F|3|1G|5|J|7|4G|8|@]|D|@]|E|$K|L]]|$1|1H|3|1I|5|6|7|4H|8|@$9|4I|A|4J|B|Y]]|D|@]|E|$]]|$1|1J|3|1K|5|6|7|4K|8|@$9|4L|A|4M|B|Y]|$9|4N|A|4O|B|Y]]|D|@]|E|$]]|$1|1L|3|1M|5|J|7|4P|8|@]|D|@]|E|$K|L]]|$1|1N|3|1O|5|6|7|4Q|8|@$9|4R|A|4S|B|Y]|$9|4T|A|4U|B|Y]|$9|4V|A|4W|B|Y]]|D|@]|E|$]]|$1|1P|3|1Q|5|6|7|4X|8|@]|D|@]|E|$]]|$1|1R|3|1S|5|J|7|4Y|8|@]|D|@]|E|$K|L]]|$1|1T|3|1U|5|6|7|4Z|8|@$9|50|A|51|B|Y]|$9|52|A|53|B|Y]|$9|54|A|55|B|Y]]|D|@$9|56|A|57|1|58]]|E|$]]|$1|1V|3|1W|5|J|7|59|8|@]|D|@]|E|$K|L]]|$1|1X|3|1Y|5|6|7|5A|8|@$9|5B|A|5C|B|Y]|$9|5D|A|5E|B|Y]]|D|@]|E|$]]|$1|1Z|3|20|5|J|7|5F|8|@]|D|@]|E|$K|L]]|$1|21|3|22|5|6|7|5G|8|@]|D|@]|E|$]]|$1|23|3|24|5|J|7|5H|8|@]|D|@]|E|$K|L]]|$1|25|3|26|5|6|7|5I|8|@]|D|@]|E|$]]|$1|27|3|28|5|J|7|5J|8|@]|D|@]|E|$K|L]]|$1|29|3|2A|5|6|7|5K|8|@]|D|@]|E|$]]|$1|2B|3|2C|5|J|7|5L|8|@]|D|@]|E|$K|L]]|$1|2D|3|2E|5|6|7|5M|8|@$9|5N|A|5O|B|Y]|$9|5P|A|5Q|B|Y]|$9|5R|A|5S|B|Y]|$9|5T|A|5U|B|Y]|$9|5V|A|5W|B|Y]]|D|@]|E|$]]|$1|2F|3|-4|5|6|7|5X|8|@]|D|@]|E|$]]]|2G|$2H|$5|2I|2J|2K|E|$2L|2M]]]]

Short version

The MATLAB code should have been written like this:

<pre><code>function [kf, Ek]=hysime(y, n, Rn, verbose);
 error(nargchk(3, 4, nargin))
 if nargin &lt; 4
 verbose = true;
 else
 verbose = ~strcmpi(verbose ,'off');
 end
</code></pre>

If you know MATLAB, this should be clearer. The (mostly) corresponding Python code can be written like this:

<pre><code>def hysime(y, n, Rn, verbose=True):
 # rest of the function here
 return kf, Ek
</code></pre>

Long Version

This function expects 3 or 4 input arguments, with a default value set if the fourth argument is not provided. However, it is done in a way that is much more complicated than it needs to be (although I see this pattern a lot). Ideally in MATLAB you would specify the same thing like this:

<pre><code>function [varargout]=hysime(y, n, Rn, verbose)
 error(nargchk(3, 4, nargin))
 if nargin &lt; 4
 verbose = true;
 else
 verbose = ~strcmpi(verbose ,'off');
 end
</code></pre>

So what it is doing is putting the first argument in the variable <code>y</code>, the second in the variable <code>n</code>, the third in <code>Rn</code>, and if the fourth is specified put it in <code>verbose</code> (based on how it compares to the string <code>'off'</code>), otherwise set <code>verbose</code> to <code>true</code>.

In python, handling of optional arguments is built-in. You can specify default value for arguments right in the function definition by setting <code>name=value</code>, where <code>name</code> is the argument name and <code>value</code> is the default value. Also, for historical reasons MATLAB often uses <code>'on'</code> and <code>'off'</code> instead of <code>true</code> and <code>false</code>. This is almost never done in Python, people just use <code>True</code> and <code>False</code>. So you can specify the same thing in Python like so:

<pre><code>def hysime(y, n, Rn, verbose=True):
</code></pre>

This makes <code>y</code>, <code>n</code>, and <code>Rn</code> required arguments, but lets <code>verbose</code> be optional. 

This doesn't handle the case where <code>verbose</code> is set to the string <code>'off'</code>. As I said, this is common in MATLAB for historical reasons, but you really shouldn't be doing it in MATLAB anymore when you can avoid it, and you definitely shouldn't be doing it in Python. But if you really, really need to handle that case, you can just do:

<pre><code>def hysime(y, n, Rn, verbose=True):
 if isinstance(verbose, str):
 verbose = verbose.lower() != 'off'
</code></pre>

For the output, what the MATLAB code does is let the function either return one value or two. So someone could do this:

<pre><code>kf = hysime(y, n, Rn);
</code></pre>

Or

<pre><code>[kf, Ek] = hysime(y, n, Rn);
</code></pre>

However, this is also being done in a way that is more complicated than necessary. If you just return the two values, and only one return value is used, MATLAB will throw away the rest. So rather than messing around with <code>varargout</code>, the function could just return <code>[kf, Ek]</code> and MATLAB will do the same thing. An error will automatically occur if someone tries to call the function with more than 2 outputs as well, so that is also unnecessary. 

Dealing with <code>varargout</code> in this way is only necessary if you want the program to change its behavior based on the number of outputs. In this sort of structure, the main reason you would do this is if <code>eK</code> was expensive to calculate, in which case you would do something like this:

<pre><code>varargout(1) = {kf};
if nargout == 2
 # calculate eK here
 varargout(2) = {Ek};
end
</code></pre>

As for the <code>return</code>, that is only needed in MATLAB if you want to cause the function to stop early, before it reaches the end normally. Once it reaches the end normally, it will <code>return</code> automatically. So if the last block of code you specified is the end of the function, then the <code>return</code> is redundant.

So all the code you showed in MATLAB can be reduced to:

<pre><code>function [kf, Ek]=hysime(y, n, Rn, verbose);
 error(nargchk(3, 4, nargin))
 if nargin &lt; 4
 verbose = true;
 else
 verbose = ~strcmpi(verbose ,'off');
 end
</code></pre>

As for Python, as I mentioned in my <a href="https://stackoverflow.com/a/51407867/3604159">other answer to you</a>, Python requires all returned values be handled. It will never throw away returned values unless you explicitly tell it to. In your case, the simplest solution is just to have <code>return kf, Ek</code> at the end of the function. If someone wants both <code>kf</code> and <code>Ek</code>, they can do:

<pre><code>kf, Ek = hysime(y, n, Rn)
</code></pre>

If they only want <code>kf</code>, they can do (where <code>_</code> is the python convention for a variable you don't care about):

<pre><code>kf, _ = hysime(y, n, Rn)
</code></pre>

Or:

<pre><code>kf = hysime(y, n, Rn)[0]
</code></pre>

So the python code would be:

<pre><code>def hysime(y, n, Rn, verbose=True):
 # rest of the function here
 return kf, Ek
</code></pre>

If you really want to be able to have one or two returned values, you would need to have another argument to change the behavior. Such as:

<pre><code>def hysime(y, n, Rn, verbose=True, ret_eK=False):
 # rest of the function here
 return (kf, Ek) if ret_eK else kf
</code></pre>

So in this case if the <code>ret_eK</code> argument is specified and set to <code>True</code>, then <code>kf, Ek</code> is returned, otherwise just <code>kf</code> is returned. But in Python you really don't want to do this unless there is some major additional cost to calculating <code>Ek</code>, which doesn't appear to be in this case.

I am trying to translate some code from Matlab to Python. The start of my function (in Matlab) starts like this:

<pre><code>function [varargout]=hysime(varargin);
 error(nargchk(3, 4, nargin))
 if nargout &gt; 2, error('too many output parameters'); end
 verbose = 1; % default value
 y = varargin{1}; % 1st parameter is the data set
</code></pre>

Later in the program there is something like this:

<pre><code>n = varargin{2}; % the 2nd parameter is the noise
Rn = varargin{3}; % the 3rd parameter is the noise correlation matrix

if nargin == 4, verbose = ~strcmp(lower(varargin{4}),'off');end
</code></pre>

and finally there is this:

<pre><code>varargout(1) = {kf};
if nargout == 2, varargout(2) = {Ek};end
return 
</code></pre>

I am incredibly confused about what this code means. On one hand I understand that the parameters inputed all need to be returned. However, at the end of the program it appears like only 2 variables will be returned (while we input 3?). How can I translate this code so that the necessary parameters are returned? I guess my biggest issue here is that the matlab code is letting the agent input the parameters however they do not all seem required? And it seems like there cannot be more than two outputs? I am just having trouble deciphering what each line of code here means. Can someone please provide an explanation both in what is happening with the matlab code and what I can do to make the same sort of functionality in python?

Thanks!

Returning variables Matlab and Python?

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我正在尝试将一些代码从Matlab翻译成Python。我的函数(在Matlab中)的开始如下所示：function [varargout]=hysime(varargin);    error(nargchk(3, 4, nargin))    if nargout > 2, error('too many outpu...

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