Create code_and_doc.md

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doc/doc_en/code_and_doc.md

+  - Appendix
+
+    This appendix contains python, document specifications and Pull Request process. Please follow the relevant contents
+
+    - [Appendix 1：Python code specification](#Appendix1)
+
+    - [Appendix 2：Document specification](#Appendix2)
+
+    - [Appendix 3：Pull Request description](#Appendix3)
+
+    <a name="Appendix1"></a>
+
+    ## Appendix 1：Python code specification
+
+    The Python code of PaddleOCR follows [PEP8 Specification]( https://www.python.org/dev/peps/pep-0008/ ), some of the key concerns include the following
+
+    - Space 
+
+      - Spaces should be added after commas, semicolons, colons, not before them
+
+        ```python
+        # true:
+        print(x, y)
+        
+        # false:
+        print(x , y)
+        ```
+
+      - When specifying a keyword parameter or default parameter value in a function, do not use spaces on both sides of it
+
+        ```python
+        # true:
+        def complex(real, imag=0.0)
+        # false:
+        def complex(real, imag = 0.0)
+        ```
+
+    - comment
+
+      - Inline comments: inline comments are indicated by the` # `sign. Two spaces should be left between code and` # `, and one space should be left between` # `and comments, for example
+
+        ```python
+        x = x + 1  # Compensate for border
+        ```
+
+      - Functions and methods: The definition of each function should include the following:
+
+        - Function description: Function function, input and output
+
+        - Args: Name of each parameter and description of the parameter
+        - Returns: The meaning and type of the return value
+
+        ```python
+        def fetch_bigtable_rows(big_table, keys, other_silly_variable=None):
+            """Fetches rows from a Bigtable.
+        
+            Retrieves rows pertaining to the given keys from the Table instance
+            represented by big_table.  Silly things may happen if
+            other_silly_variable is not None.
+        
+            Args:
+                big_table: An open Bigtable Table instance.
+                keys: A sequence of strings representing the key of each table row
+                    to fetch.
+                other_silly_variable: Another optional variable, that has a much
+                    longer name than the other args, and which does nothing.
+        
+            Returns:
+                A dict mapping keys to the corresponding table row data
+                fetched. Each row is represented as a tuple of strings. For
+                example:
+        
+                {'Serak': ('Rigel VII', 'Preparer'),
+                 'Zim': ('Irk', 'Invader'),
+                 'Lrrr': ('Omicron Persei 8', 'Emperor')}
+        
+                If a key from the keys argument is missing from the dictionary,
+                then that row was not found in the table.
+            """
+            pass
+        ```
+
+    <a name="Appendix2"></a>
+
+    ## Appendix 2: Document Specification
+
+    ### 2.1 Overall description
+
+    - Document Location: If you add new features to your original Markdown file, please **Do not re-create** a new file. If you don't know where to add it, you can first PR the code and then ask the official in commit.
+
+    - New Markdown Document Name: Describe the content of the document in English, typically a combination of lowercase letters and underscores, such as `add_New_Algorithm.md`
+
+    - New Markdown Document Format: Catalog - Body - FAQ
+
+      > The directory generation method can use [this site](https://ecotrust-canada.github.io/markdown-toc/ ) Automatically extract directories after copying MD contents, and then add `<a name='XXXX'></a> before each heading of the MD file
+
+    - English and Chinese: Any changes or additions to the document need to be made in both Chinese and English documents.
+
+    ### 2.2 Format Specification
+
+    - Title format: The document title format follows the format of: Arabic decimal point combination-space-title (for example, `2.1 XXXX`, `2.XXXX`)
+
+    - Code block: Displays code in code block format that needs to be run, describing the meaning of command parameters before the code block. for example:
+
+      > Whole Process Detect+Direction Classifier+Identify : Vertical text can be recognized after set direction classifier parameters`--use_angle_cls true`.
+      >
+      > ```
+      > paddleocr --image_dir ./imgs/11.jpg --use_angle_cls true
+      > ```
+
+    - Variable Rrferences: If code variables or command parameters are referenced in line, they need to be represented in line code, for example, above `--use_angle_cls true` with one space in front and one space in back
+
+    - Uniform naming: e.g. PP-OCRv2, PP-OCR mobile, `paddleocr` whl package, PPOCRLabel, Paddle Lite, etc.
+
+    - Supplementary notes: Supplementary notes by reference format `>`.
+
+    - Picture: If a picture is added to the description document, specify the naming of the picture (describing its content) and add the picture under `doc/`.
+
+    <a name="Appendix3"></a>
+
+    ## Appendix 3: Pull Request Description
+
+    ### 3.1 PaddleOCR branch description
+
+    PaddleOCR will maintain two branches in the future, one for each:
+
+    - release/x.x family branch: stable release version branch, also the default branch. PaddleOCR releases a new release branch based on feature updates and adapts to the release version of Paddle. As versions iterate, more and more release/x.x family branches are maintained by default with the latest version of the release branch.
+    - dygraph branch: For the development branch, adapts the dygraph version of the Paddle dynamic graph to primarily develop new functionality. If you need to redevelop, choose the dygraph branch. To ensure that the dygraph branch pulls out the release/x.x branch when needed, the code for the dygraph branch can only use the valid API in the latest release branch of Paddle. That is, if a new API has been developed in the Paddle dygraph branch but has not yet appeared in the release branch code, do not use it in Paddle OCR. In addition, performance optimization, parameter tuning, policy updates that do not involve API can be developed normally.
+
+    The historical branch of PaddleOCR will no longer be maintained in the future. These branches will continue to be maintained, considering that some of you may still be using them:
+
+    - Develop branch: This branch was used for the development and testing of static diagrams and is currently compatible with version >=1.7. If you have special needs, you can also use this branch to accommodate older versions of Paddle, but you won't update your code until you fix the bug.
+
+    PaddleOCR welcomes you to actively contribute code to repo. Here are some basic processes for contributing code.
+
+    ### 3.2 PaddleOCR Code Submission Process and Specification
+
+    > If you are familiar with Git use, you can jump directly to [some conventions for submitting code in 3.2.10](#some_conventions_for_submitting code)
+
+    #### 3.2.1 Create Your `Remote repo`
+
+    - In PaddleOCR [GitHub Home]( https://github.com/PaddlePaddle/PaddleOCR ) Click the `Fork` button in the upper left corner to create a `remote repo`in your personal directory, such as ` https://github.com/ {your_name}/PaddleOCR`.
+
+    ![banner](../banner.png)
+
+    - Clone `Remote repo`
+
+    ```
+    # pull code of develop branch
+    git clone https://github.com/{your_name}/PaddleOCR.git -b dygraph
+    cd PaddleOCR
+    ```
+
+    > Clone failures are mostly due to network reasons, try again later or configure the proxy
+
+    #### 3.2.2 Connect with `Remote repo`
+
+    First view the current `remote repo`information.
+
+    ```
+    git remote -v
+    # origin    https://github.com/{your_name}/PaddleOCR.git (fetch)
+    # origin    https://github.com/{your_name}/PaddleOCR.git (push)
+    ```
+
+    Then create a remote host named upstream for the original PaddleOCR repo.
+
+    ```
+    git remote add upstream https://github.com/PaddlePaddle/PaddleOCR.git
+    ```
+
+    Use `git remote-v` to view current `remote warehouse` information, output as follows, found to include two origin and two upstream of `remote repo` .
+
+    ```
+    origin    https://github.com/{your_name}/PaddleOCR.git (fetch)
+    origin    https://github.com/{your_name}/PaddleOCR.git (push)
+    upstream    https://github.com/PaddlePaddle/PaddleOCR.git (fetch)
+    upstream    https://github.com/PaddlePaddle/PaddleOCR.git (push)
+    ```
+
+    This is mainly to keep the local repository up to date when subsequent pull request (PR) submissions are made.
+
+    #### 3.2.3 Create Local Branch
+
+    You can create a new local branch based on the current branch with the following commands.
+
+    ```
+    git checkout -b new_branch
+    ```
+
+    You can also create a new branch based on a remote or upstream branch with the following commands.
+
+    ```
+    # Create new_branch branch on user remote repo (origin) based on develop branch
+    git checkout -b new_branch origin/develop
+    # Create new_branch branch based on upstream remote repo develop branch
+    # If you need to create a new branch from upstream, you need to first use git fetch upstream to get upstream code
+    git checkout -b new_branch upstream/develop
+    ```
+
+    The final switch to the new branch is displayed with the following output information.
+
+    ```
+    Branch new_branch set up to track remote branch develop from upstream.
+    Switched to a new branch 'new_branch'
+    ```
+
+    #### 3.2.4 Use pre-commit hook
+
+    Paddle developers use the pre-commit tool to manage Git pre-submit hooks. It helps us format the source code (C++, Python) and automatically check for basic things (such as having only one EOL per file, not adding large files to Git) before committing it.
+
+    The pre-commit test is part of the unit test in Travis-CI. PR that does not satisfy the hook cannot be submitted to PaddleOCR. Install it first and run it in the current directory：
+
+    ```
+    pip install pre-commit
+    pre-commit install
+    ```
+
+     >  1. Paddle uses clang-format to adjust the C/C++ source code format. Make sure the `clang-format` version is above 3.8.
+     >
+     >  2. Yapf installed through pip install pre-commit is slightly different from conda install-c conda-forge pre-commit, and PaddleOCR developers use `pip install pre-commit`.
+
+    #### 3.2.5 Modify and submit code
+
+     If you make some changes on `README.Md ` on PaddleOCR, you can view the changed file through `git status`, and then add the changed file using `git add`。
+
+    ```
+    git status # View change files
+    git add README.md
+    pre-commit
+    ```
+
+    Repeat these steps until the pre-comit format check does not error. As shown below.
+
+    ![img](../precommit_pass.png)
+
+    Use the following command to complete the submission.
+
+    ```
+    git commit -m "your commit info"
+    ```
+
+    #### 3.2.6 Keep local warehouses up to date
+
+    Get the latest code for upstream and update the current branch. Here the upstream comes from section 2.2, `Connecting to a remote repo`.
+
+    ```
+    git fetch upstream
+    # If you want to commit to another branch, you need to pull code from another branch of upstream, here is develop
+    git pull upstream develop
+    ```
+
+    #### 3.2.7 Push to remote repo
+
+    ```
+    git push origin new_branch
+    ```
+
+    #### 3.2.7 Submit Pull Request
+
+    Click the new pull request to select the local branch and the target branch, as shown in the following figure. In the description of PR, fill in the functions completed by the PR. Next, wait for review, and if you need to modify something, update the corresponding branch in origin with the steps above.
+
+    ![banner](../pr.png)
+
+    #### 3.2.8 Sign CLA agreement and pass unit tests
+
+    - Signing the CLA When submitting a Pull Request to PaddlePaddle for the first time, you need to sign a CLA (Contributor License Agreement) agreement to ensure that your code can be incorporated as follows:
+
+      1. Please check the Check section in PR, find the license/cla, and click on the right detail to enter the CLA website
+
+      2. Click Sign in with GitHub to agree on the CLA website and when clicked, it will jump back to your Pull Request page
+
+    #### 3.2.9 Delete Branch
+
+    - Remove remote branch
+
+      After PR is merged into the main repo, we can delete the branch of the remote repofrom the PR page.
+      You can also use `git push origin:branch name` to delete remote branches, such as:
+
+  ```
+    git push origin :new_branch
+  ```
+
+- Delete local branch
+
+  ```
+      # Switch to the development branch, otherwise the current branch cannot be deleted
+      git checkout develop
+      
+      # Delete new_ Branch Branch
+      git branch -D new_branch
+  ```
+
+    <a name="Some_conventions_for_submitting_code"></a>
+
+    #### 3.2.10 Some conventions for submitting code
+
+    In order for official maintainers to better focus on the code itself when reviewing it, please follow the following conventions each time you submit your code:
+
+    1）Please ensure that the unit tests in Travis-CI pass smoothly. If not, indicate that there is a problem with the submitted code, and the official maintainer generally does not review it.
+    
+    2）Before submitting a Pull Request.
+    
+    - Note the number of commits.
+
+      Reason: If you only modify one file and submit more than a dozen commits, each commit will only make a few modifications, which can be very confusing to the reviewer. The reviewer needs to look at each commit individually to see what changes have been made, and does not exclude the fact that changes between commits overlap each other.
+      
+      Suggestion: Keep as few commits as possible each time you submit, and supplement your last commit with git commit --amend. For multiple commits that have been Push to a remote warehouse, you can refer to [squash commits after push](https://stackoverflow.com/questions/5667884/how-to-squash-commits-in-git-after-they-have-been-pushed ).
+
+    - Note the name of each commit: it should reflect the content of the current commit, not be too arbitrary.
+
+
+    3） If you have solved a problem, add in the first comment box of the Pull Request:fix #issue_number，This will automatically close the corresponding Issue when the Pull Request is merged. Key words include:close, closes, closed, fix, fixes, fixed, resolve, resolves, resolved,please choose the right vocabulary. Detailed reference [Closing issues via commit messages](https://help.github.com/articles/closing-issues-via-commit-messages).
+    
+    In addition, in response to the reviewer's comments, you are requested to abide by the following conventions:
+    
+    1） Each review comment from an official maintainer would like a response, which would better enhance the contribution of the open source community.
+    
+    - If you agree to the review opinion and modify it accordingly, give a simple Done.
+    - If you disagree with the review, please give your own reasons for refuting.
+    
+    2）If there are many reviews:
+    
+    - Please give an overview of the changes.
+    - Please reply with `start a review', not directly. The reason is that each reply sends an e-mail message, which can cause a mail disaster.