EM | EM algorithm to solve the problem in page | Learning library
kandi X-RAY | EM Summary
kandi X-RAY | EM Summary
The example of EM algorithm to solve the problem in page 137 of Machine Learning book(Chinese Edition) written by Tom M. Mitchell. 假设全部数据Z是由可观测到的样本![] X_2，……, X_n})和不可观测到的样本![] Z_2，……, Z_n})组成的，则Y = X∪Z。. ![] h'| h) = E [ ln P(Y|h') | h, X ]). 步骤1：估计（E）步骤：使用当前假设h和观察到的数据X来估计Y上的概率分布以计算$Q( h' | h )$。. ![] h' | h ) \leftarrow {E[ ln P(Y|h') | h, X ]}). ![] h \leftarrow {argmaxQ( h' | h )}).
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- Run the optimizer
- Calculates E - step expectations
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QUESTION
I have prepare 2 tree view in separate iframe using jstree. The right tree view should control the left tree view. When user click one one the list in right tree view, the respective item folder will open and selected on left tree view. I can make it happen using div in single page. I control the left tree view using instance of left tree view in right jstree div var instance = $('#left').jstree(true);.
ANSWER
Answered 2021-Jun-16 at 03:07I had used document.getElementById('1').contentWindow.jQuery('#left').jstree(true); to get instance from iframe with id='1'. In order to listen to right iframe(with id='2') if any menu has been clicked, I used document.getElementById('2').contentWindow.jQuery('#right').on("changed.jstree",function(e,data){}). I get the instance of left iframe within this function. By using this instance, I has deselect previous selection, select current selection, and open children of selected menu.
index-12.html
QUESTION
I want to have my reference counted C++ object also managed in Lua callbacks: when it is held by a Lua variable, increase its refcount; and when the Lua variable is destroyed, release one refcount. It seems the releasing side can be automatically performed by __gc meta-method, but how to implement the increasing side?
Is it proper&enough to just increase refcount every time before adding the object to Lua stack?
Or maybe I should new a smart pointer object, use it everywhere in Lua C function, then delete it in __gc meta-method? This seems ugly as if something wrong with the Lua execution and the __gc is not called, the newed smart pointer object will be leaked, and the refcounted object it is referring would have leak one count.
In Perl that I'm more familiar with, this can be achieved by increase refcount at OUTPUT section of XS Map, and decrease refcount at destroyer.
ANSWER
Answered 2021-Jun-10 at 19:23I assume you have implemented two Lua functions in C: inc_ref_count(obj) and dec_ref_count(obj)
QUESTION
I understand that after calling fork() the child process inherits the per-process file descriptor table of its parent (pointing to the same system-wide open file tables). Hence, when opening a file in a parent process and then calling fork(), both the child and parent can write to that file without overwriting one another's output (due to a shared offset in the open-file table entry).
However, suppose that, we call open() on some file after a fork (in both the parent and the child). Will this create a separate entries in the system-wide open file table, with a separate set of offsets and read-write permission flags for the child (despite the fact that it's technically the same file)? I've tried looking this up and I don't seem to be able to find a clear answer.
I'm asking this mainly since I was playing around with writing to files, and it seems like only one the outputs of the parent and child ends up in the file in the aforementioned situation. This seemed to imply that there are separate entries in the open file table for the two separate open calls, and hence separate offsets, so the slower process overwrites the output of the other process.
To illustrate this, consider the following code:
...ANSWER
Answered 2021-May-03 at 20:22There is a difference between a file and a file descriptor (FD).
All processes share the same files. They don't necessarily have access to the same files, and a file is not its name, either; two different processes which open the same name might not actually open the same file, for example if the first file were renamed or unlinked and a new file were associated with the name. But if they do open the same file, it's necessarily shared, and changes will be mutually visible.
But a file descriptor is not a file. It refers to a file (not a filename, see above), but it also contains other information, including a file position used for and updated by calls to read and write. (You can use "positioned" read and write, pread and pwrite, if you don't want to use the position in the FD.) File descriptors are shared between parent and child processes, and so the file position in the FD is also shared.
Another thing stored in the file descriptor (in the kernel, where user processes can't get at it) is the list of permitted actions (on Unix, read, write, and/or execute, and possibly others). Permissions are stored in the file directory, not in the file itself, and the requested permissions are copied into the file descriptor when the file is opened (if the permissions are available.) It's possible for a child process to have a different user or group than the parent, particularly if the parent is started with augmented permissions but drops them before spawning the child. A file descriptor for a file opened in this manner still has the same permissions uf it is shared with a child, even if the child would itself be able to open the file.
QUESTION
So, if I had a data table like this:
...ANSWER
Answered 2021-Jun-15 at 23:07One solution is to use tidyverse functions group_by() and summarise():
QUESTION
I am trying to define a subroutine in Raku whose argument is, say, an Array of Ints (imposing that as a constraint, i.e. rejecting arguments that are not Arrays of Ints).
Question: What is the "best" (most idiomatic, or straightforward, or whatever you think 'best' should mean here) way to achieve that?
Examples run in the Raku REPL follow.
What I was hoping would work
...ANSWER
Answered 2021-Jun-15 at 06:40I think the main misunderstanding is that my Int @a = 1,2,3 and [1,2,3] are somehow equivalent. They are not. The first case defines an array that will only take Int values. The second case defines an array that will take anything, and just happens to have Int values in it.
I'll try to cover all versions you tried, why they didn't work, and possibly how it would work. I'll be using a bare dd as proof that the body of the function was reached.
#1
QUESTION
So I was fetching data from my database to print in a table however, it says that Class "App\Http\Controllers\User" not found. Here is the controller and here is how I will print the data
...ANSWER
Answered 2021-Jun-15 at 22:42At the top off your controller add
Laravel 8+
QUESTION
In C++20, we got the capability to sleep on atomic variables, waiting for their value to change.
We do so by using the std::atomic::wait method.
Unfortunately, while wait has been standardized, wait_for and wait_until are not. Meaning that we cannot sleep on an atomic variable with a timeout.
Sleeping on an atomic variable is anyway implemented behind the scenes with WaitOnAddress on Windows and the futex system call on Linux.
Working around the above problem (no way to sleep on an atomic variable with a timeout), I could pass the memory address of an std::atomic to WaitOnAddress on Windows and it will (kinda) work with no UB, as the function gets void* as a parameter, and it's valid to cast std::atomic to void*
On Linux, it is unclear whether it's ok to mix std::atomic with futex. futex gets either a uint32_t* or a int32_t* (depending which manual you read), and casting std::atomic to u/int* is UB. On the other hand, the manual says
The uaddr argument points to the futex word. On all platforms, futexes are four-byte integers that must be aligned on a four- byte boundary. The operation to perform on the futex is specified in the futex_op argument; val is a value whose meaning and purpose depends on futex_op.
Hinting that alignas(4) std::atomic should work, and it doesn't matter which integer type is it is as long as the type has the size of 4 bytes and the alignment of 4.
Also, I have seen many places where this trick of combining atomics and futexes is implemented, including boost and TBB.
So what is the best way to sleep on an atomic variable with a timeout in a non UB way? Do we have to implement our own atomic class with OS primitives to achieve it correctly?
(Solutions like mixing atomics and condition variables exist, but sub-optimal)
...ANSWER
Answered 2021-Jun-15 at 20:48You shouldn't necessarily have to implement a full custom atomic API, it should actually be safe to simply pull out a pointer to the underlying data from the atomic and pass it to the system.
Since std::atomic does not offer some equivalent of native_handle like other synchronization primitives offer, you're going to be stuck doing some implementation-specific hacks to try to get it to interface with the native API.
For the most part, it's reasonably safe to assume that first member of these types in implementations will be the same as the T type -- at least for integral values [1]. This is an assurance that will make it possible to extract out this value.
... and casting
std::atomictou/int*is UB
This isn't actually the case.
std::atomic is guaranteed by the standard to be Standard-Layout Type. One helpful but often esoteric properties of standard layout types is that it is safe to reinterpret_cast a T to a value or reference of the first sub-object (e.g. the first member of the std::atomic).
As long as we can guarantee that the std::atomic contains only the u/int as a member (or at least, as its first member), then it's completely safe to extract out the type in this manner:
QUESTION
When using ls -l, I noticed that directories start with 2 hard links, and gain one for each subdirectory. I understand that the current directory link . counts as one link and the parent directory link .. of each subdirectory counts as a hard link, but:
Why don't subfiles count towards hard links when subdirectories do?
Why does the parent directory link
..count as a hard link for both this directory and the parent directory?
ANSWER
Answered 2021-Jun-15 at 20:37Assume the following directory tree
QUESTION
I would like to extract the definitions from the book The Navajo Language: A Grammar and Colloquial Dictionary by Young and Morgan. They look like this (very blurry):
I tried running it through the Google Cloud Vision API, and got decent results, but it doesn't know what to do with these "special" letters with accent marks on them, or the curls and lines on/through them. And because of the blurryness (there are no alternative sources of the PDF), it gets a lot of them wrong. So I'm thinking of doing it from scratch in Tesseract. Note the term is bold and the definition is not bold.
How can I use Node.js and Tesseract to get basically an array of JSON objects sort of like this:
...ANSWER
Answered 2021-Jun-15 at 20:17Tesseract takes a lang variable that you can expand to include different languages if they're installed. I've used the UB Mannheim (https://github.com/UB-Mannheim/tesseract/wiki) installation which includes a ton of languages supported.
To get better and more accurate results, the best thing to do is to process the image before handing it to Tesseract. Set a white/black threshold so that you have black text on white background with no shading. I'm not sure how to do this in Node, but I've done it with Python's OpenCV library.
If that font doesn't get you decent results with the out of the box, then you'll want to train your own, yes. This blog post walks through the process in great detail: https://towardsdatascience.com/simple-ocr-with-tesseract-a4341e4564b6. It revolves around using the jTessBoxEditor to hand-label the objects detected in the images you're using.
Edit: In brief, the process to train your own:
- Install jTessBoxEditor (https://sourceforge.net/projects/vietocr/files/jTessBoxEditor/). Requires Java Runtime installed as well.
- Collect your training images. They want to be .tiffs. I found I got fairly accurate results with not a whole lot of images that had a good sample of all the characters I wanted to detect. Maybe 30/40 images. It's tedious, so you don't want to do TOO many, but need enough in order to get a good sampling.
- Use jTessBoxEditor to merge all the images into a single .tiff
- Create a training label file (.box)j. This is done with Tesseract itself.
tesseract your_language.font.exp0.tif your_language.font.exp0 makebox - Now you can open the box file in jTessBoxEditor and you'll see how/where it detected the characters. Bounding boxes and what character it saw. The tedious part: Hand fix all the bounding boxes and characters to accurately represent what is in the images. Not joking, it's tedious. Slap some tv episodes up and just churn through it.
- Train the tesseract model itself
- save a file:
font_propertieswho's content isfont 0 0 0 0 0 - run the following commands:
tesseract num.font.exp0.tif font_name.font.exp0 nobatch box.train
unicharset_extractor font_name.font.exp0.box
shapeclustering -F font_properties -U unicharset -O font_name.unicharset font_name.font.exp0.tr
mftraining -F font_properties -U unicharset -O font_name.unicharset font_name.font.exp0.tr
cntraining font_name.font.exp0.tr
You should, in there close to the end see some output that looks like this:
Master shape_table:Number of shapes = 10 max unichars = 1 number with multiple unichars = 0
That number of shapes should roughly be the number of characters present in all the image files you've provided.
If it went well, you should have 4 files created: inttemp normproto pffmtable shapetable. Rename them all with the prefix of your_language from before. So e.g. your_language.inttemp etc.
Then run:
combine_tessdata your_language
The file: your_language.traineddata is the model. Copy that into your Tesseract's data folder. On Windows, it'll be like: C:\Program Files x86\tesseract\4.0\tessdata and on Linux it's probably something like /usr/shared/tesseract/4.0/tessdata.
Then when you run Tesseract, you'll pass the lang=your_language. I found best results when I still passed an existing language as well, so like for my stuff it was still English I was grabbing, just funny fonts. So I still wanted the English as well, so I'd pass: lang=your_language+eng.
QUESTION
I'm trying to create a new variable based on some conditions. I have the following data:
...ANSWER
Answered 2021-Jun-15 at 16:13We can use a group by operation in dplyr i.e. grouped by 'ID', extract the 'code' where the 'type' value is "large" (assuming there are no duplicate values for 'type' within each 'ID'
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You can use EM like any standard Python library. You will need to make sure that you have a development environment consisting of a Python distribution including header files, a compiler, pip, and git installed. Make sure that your pip, setuptools, and wheel are up to date. When using pip it is generally recommended to install packages in a virtual environment to avoid changes to the system.
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