As you have already found out, the difference between `exists` and `isfile` is the fact that the former returns `True` in case the given path is a directory **or** a file, while the latter only returns `True` if the path points to a file.

**Directories** and **files** are quite similar from the technical point of view. A file can contain any kind of data. A directory is just a special entry in the file system (at least on Unix operating systems it is just a special file) that represents the fact that it may contain files and other directories. It is a helpful means for building up a data structure. Using directories, you can organize your data in a hierarchical structure.

Especially in the Windows world, directories are often called &quot;folders&quot;. I am sure that you yourself are using &quot;folders&quot; for organizing your files.

A **path** is an unambiguous pointer to a resource in the file system. It can either point to a file or to a directory. 

A directory tests true for exists, but false for isfile. There are a few different types of filesystem objects for which that is also true.

isfile means that it is a regular file. It is more specific than exists.

os.path.exists returns if it is a valid path(check for directory or file, both) whereas os.path.isfile(checks for only file, not directory) 

I&#39;m trying to create this generic method to simplify things but I think I messed it up! Can you help with my problem?

This compiles:

    private string ConcatenateText&lt;T1, T2&gt;(MyEntity myEntity) 
        where T1 : Supplier, new()
        where T1 : Employee, new()
        where T2 : SupplierDepartment, new()
        where T2 : EmployeeDepartment, new()
    {
        T1 p = new T1();
        T2 r = new T2();
        //Code here for myEntity treatment
        return mystring;
    }

While this does not compile:

    protected void mybutton1_Click(object sender, EventArgs e)
    {
       string mystring = ConcatenaText&lt;Supplier, SupplierDepartment&gt;(myEntity);
    }
    
    //This does not compile
    protected void mybutton2_Click(object sender, EventArgs e)
    {
       string mystring = ConcatenaText&lt;Employee, EmployeeDepartment&gt;(myEntity);
    }

**Message: The type Supplier cannot be used as type parameter T1 in the generic type or method ConcatenateText&lt;T1, T2&gt;(MyEntity myEntity). There is no implicit reference conversion from Supplier to Employee**

Can this be done? What am I doing wrong? Can it be improved?


**EDIT:**

And MyEntity is just another class in order to process it inside this generic method! It&#39;s not related to the types T. It just an argument. But it&#39;s clear that I can&#39;t do that, using 2 types like that. I thought that I could assign one or another and the CLR independently of my initialization could react as I wanted. I gonna accept the answer who share a little bit more information about it.

Generic with multiple classes

What is `ffreestanding` in gcc ? What is it used for ? I came across the following :

    gcc -ffreestanding -m32 -c kernel.c -o kernel.o

and do not understand, what does it mean exactly.


What is -ffreestanding option in gcc?

I&#39;m curious when these two functions will return different values. Also if  you could clarify the difference between a path/directory/file that would be appreciated.

Difference between os.path.exists and os.path.isfile?

<p>I'm curious when these two functions will return different values. Also if  you could clarify the difference between a path/directory/file that would be appreciated.</p>


I have a piece of code which is working in Linux, and I am now trying to run it in windows, I import sys but when I use sys.exit(). I get an error, sys is not defined. Here is the begining part of my code

    try:
        import numpy as np
        import pyfits as pf
        import scipy.ndimage as nd
        import pylab as pl
        import os
        import heapq
        import sys
        from scipy.optimize import leastsq

    except ImportError:
        print &quot;Error: missing one of the libraries (numpy, pyfits, scipy, matplotlib)&quot;
        sys.exit()

Why is sys not working??



python: sys is not defined

I come from a sql background and I use the following data processing step frequently:

1.  Partition the table of data by one or more fields
2.  For each partition, add a rownumber to each of its rows that ranks the row by one or more other fields, where the analyst specifies ascending or descending

EX:  
    
    df = pd.DataFrame({&#39;key1&#39; : [&#39;a&#39;,&#39;a&#39;,&#39;a&#39;,&#39;b&#39;,&#39;a&#39;],
               &#39;data1&#39; : [1,2,2,3,3],
               &#39;data2&#39; : [1,10,2,3,30]})
    df
         data1        data2     key1    
    0    1            1         a           
    1    2            10        a        
    2    2            2         a       
    3    3            3         b       
    4    3            30        a        

I&#39;m looking for how to do the PANDAS equivalent to this sql window function:

    RN = ROW_NUMBER() OVER (PARTITION BY Key1 ORDER BY Data1 ASC, Data2 DESC)


        data1        data2     key1    RN
    0    1            1         a       1    
    1    2            10        a       2 
    2    2            2         a       3
    3    3            3         b       1
    4    3            30        a       4

I&#39;ve tried the following which I&#39;ve gotten to work where there are no &#39;partitions&#39;:

    def row_number(frame,orderby_columns, orderby_direction,name):
        frame.sort_index(by = orderby_columns, ascending = orderby_direction, inplace = True)
        frame[name] = list(xrange(len(frame.index)))

I tried to extend this idea to work with partitions (groups in pandas) but the following didn&#39;t work:

    df1 = df.groupby(&#39;key1&#39;).apply(lambda t: t.sort_index(by=[&#39;data1&#39;, &#39;data2&#39;], ascending=[True, False], inplace = True)).reset_index()

    def nf(x):
        x[&#39;rn&#39;] = list(xrange(len(x.index)))

    df1[&#39;rn1&#39;] = df1.groupby(&#39;key1&#39;).apply(nf)

But I just got a lot of NaNs when I do this.

Ideally, there&#39;d be a succinct way to replicate the window function capability of sql (i&#39;ve figured out the window based aggregates...that&#39;s a one liner in pandas)...can someone share with me the most idiomatic way to number rows like this in PANDAS?

SQL-like window functions in PANDAS: Row Numbering in Python Pandas Dataframe

I have this function that calls itself:

    def get_input():
        my_var = input(&#39;Enter &quot;a&quot; or &quot;b&quot;: &#39;)
    
        if my_var != &quot;a&quot; and my_var != &quot;b&quot;:
            print(&#39;You didn\&#39;t type &quot;a&quot; or &quot;b&quot;. Try again.&#39;)
            get_input()
        else:
            return my_var

    print(&#39;got input:&#39;, get_input())

Now, if I input just &quot;a&quot; or &quot;b&quot;, everything works fine:

&lt;!-- language: none --&gt;

    Type &quot;a&quot; or &quot;b&quot;: a
    got input: a

But, if I type something else and then &quot;a&quot; or &quot;b&quot;, I get this:

&lt;!-- language: none --&gt;

    Type &quot;a&quot; or &quot;b&quot;: purple
    You didn&#39;t type &quot;a&quot; or &quot;b&quot;. Try again.
    Type &quot;a&quot; or &quot;b&quot;: a
    got input: None

I don&#39;t know why `get_input()` is returning `None` since it should only return `my_var`. Where is this `None` coming from and how do I fix my function?


Why does my recursive function return None?

How do you find the top correlations in a correlation matrix with Pandas? There are many answers on how to do this with R (https://stackoverflow.com/questions/7074246/show-correlations-as-an-ordered-list-not-as-a-large-matrix or https://stackoverflow.com/questions/11268822/efficient-way-to-get-highly-correlated-pairs-from-large-data-set-in-python-or-r), but I am wondering how to do it with pandas? In my case the matrix is 4460x4460, so can&#39;t do it visually.



List Highest Correlation Pairs from a Large Correlation Matrix in Pandas?

when i setup application.py, it shows that socket.error: [Errno 98] Address already in use.

    Traceback (most recent call last):
    File &quot;application.py&quot;, line 121, in &lt;module&gt;
    main()
    File &quot;application.py&quot;, line 117, in main
    http_server.listen(options.port)
    File &quot;/usr/local/lib/python2.7/site-packages/tornado-3.1-py2.7.egg/tornado/tcpserver.py&quot;, line 117, in listen
    sockets = bind_sockets(port, address=address)
    File &quot;/usr/local/lib/python2.7/site-packages/tornado-3.1-py2.7.egg/tornado/netutil.py&quot;, line 90, in bind_sockets
    sock.bind(sockaddr)
    File &quot;/usr/local/lib/python2.7/socket.py&quot;, line 224, in meth
    return getattr(self._sock,name)(*args)
    socket.error: [Errno 98] Address already in use

python socket.error: [Errno 98] Address already in use

I want to read huge text file line by line (and stop if a line with &quot;str&quot; found).
How to check, if file-end is reached?

    fn = &#39;t.log&#39;
    f = open(fn, &#39;r&#39;)
    while not _is_eof(f): ## how to check that end is reached?
        s = f.readline()
        print s
        if &quot;str&quot; in s: break

Python: read all text file lines in loop

I am still learning Symfony2 and don&#39;t understand how to upload a file.

Don&#39;t worry, I&#39;ve already checked [the documentation](http://symfony.com/doc/current/cookbook/doctrine/file_uploads.html). It&#39;s really good, but my problem isn&#39;t explained in any tutorial.

I am looking for guidance on how to upload a file with Symfony2 but with all the thing everybody needs (such as constraint of extension, rename of the file based on the id and stuff, store the path in the db, etc...)

I found good tutorials, tried to mixed them but with no success. Each time a different problem appears: file re-uploads on every submit on the form (even if the file field is empty), guessExtension impossible to used, tmp path stored in the database instead of the right path, file not moved, impossible to used the id in the rename because the id is on auto-increment and so not yet generated).

So, I&#39;ll put an &#39;standard&#39; entity, let say: Photo.php

    /**
     * Photo
     *
     * @ORM\Table(name=&quot;photo&quot;)
     * @ORM\Entity
     * @ORM\HasLifecycleCallbacks
     */
    class Photo
    {
        // Annotation for the id and auto increment etc
        private $id;
    
        /**
         * @var string
         * @Assert\File( maxSize = &quot;3072k&quot;, mimeTypesMessage = &quot;Please upload a valid Image&quot;)
         * @ORM\Column(name=&quot;image&quot;, type=&quot;string&quot;, length=245, nullable=false)
         */
        private $image
    
        private $title
    
        private $description
    
        // all the function get, set for the 4 previous variables
    }
    
and the controller:
    
    public function addPhotoAction()
    {
        $add_photo = new Photo;
        $formBuilderPhoto = $this-&gt;createFormBuilder($add_photo);
        $formBuilderPhoto
            -&gt;add(&#39;title&#39;,&#39;text&#39;,array(&#39;label&#39;  =&gt; &#39;Title of the photo&#39;, &#39;required&#39; =&gt; true))
            -&gt;add(&#39;image&#39;,&#39;file&#39;, array(&#39;required&#39; =&gt; true, &#39;data_class&#39; =&gt; null))
            -&gt;add(&#39;description&#39;,&#39;textarea&#39;,array(&#39;label&#39; =&gt; &#39;Description of your photo&#39;, &#39;required&#39; =&gt; false))
        ;
    
        $form_photo = $formBuilderPhoto-&gt;getForm();
    
        if ($request-&gt;getMethod() == &#39;POST&#39;) {
            $form_photo-&gt;bind($request);
            if ($form_photo-&gt;isValid()) {
                // ...
            }
        }
        return $this-&gt;render(&#39;MyBundle:frontend:photo.html.twig&#39;,
            array(&#39;form_photo&#39; =&gt; $form_photo-&gt;createView())
        );
    }

Do you know now what are the &#39;important&#39; function to add to be able to upload the photo and rename it ?

How do you check the extension to see if the upload is possible?

What is your actual way of doing such a thing with Symfony2? I know there is a lot of Bundle that do all those things for you but I want to learn to do it and understand the process.

What is the &#39;classic&#39; way to implement a file upload form and rename function with Symfony2?


Symfony2 file upload step by step

I have a bat file like this:

    ipconfig

That will print out the IP info to the screen, but before the user can read that info CMD closes itself.

I believe that CMD assumes the script has finished, so it closes.

How do I keep CMD open after the script is finished?

Keep CMD open after BAT file executes

Depending on the use case, how do I  constrain the number of files that dropzone.js will allow?

For example, I might need to only allow 1, 2, or 4 files uploaded.

It&#39;s not `uploadMultiple`. Unfortunately, `uploadMultiple` only applies to the number of files handled per request.

How to limit the number of dropzone.js files uploaded?

I would like to check if a given directory exists. I know how to do this on Windows: 

    BOOL DirectoryExists(LPCTSTR szPath)
    {
      DWORD dwAttrib = GetFileAttributes(szPath);
    
      return (dwAttrib != INVALID_FILE_ATTRIBUTES &amp;&amp; 
             (dwAttrib &amp; FILE_ATTRIBUTE_DIRECTORY));
    }

and Linux:

    DIR* dir = opendir(&quot;mydir&quot;);
    if (dir)
    {
        /* Directory exists. */
        closedir(dir);
    }
    else if (ENOENT == errno)
    {
        /* Directory does not exist. */
    }
    else
    {
        /* opendir() failed for some other reason. */
    }

But I need a portable way of doing this .. Is there any way to check if a directory exists no matter what OS Im using? Maybe C standard library way? 

**I know that I can use preprocessors directives and call those functions on different OSes but thats not the solution Im asking for.**

**I END UP WITH THIS, AT LEAST FOR NOW:**

    #include &lt;sys/types.h&gt;
    #include &lt;sys/stat.h&gt;
    #include &lt;stdio.h&gt;
    #include &lt;stdlib.h&gt;
    
    int dirExists(const char *path)
    {
        struct stat info;
    
        if(stat( path, &amp;info ) != 0)
            return 0;
        else if(info.st_mode &amp; S_IFDIR)
            return 1;
        else
            return 0;
    }
    
    int main(int argc, char **argv)
    {
        const char *path = &quot;./TEST/&quot;;
        printf(&quot;%d\n&quot;, dirExists(path));
        return 0;
    }



Portable way to check if directory exists [Windows/Linux, C]

I have seen similar questions ([1][1], [2][2] and [3][3]), but I don&#39;t get a proper solution from them. 

I need to ignore all files under a particular folder except for a specific file type. The folder is a subdirectory for the root path. Let me name the folder `Resources`. Since I don&#39;t want to complicate things, let me ignore files under all folders named **`Resources`** wherever it is.

This is the most common solution (in all the duplicate questions)

    # Ignore everything
    *

    # Don&#39;t ignore directories, so we can recurse into them
    !*/

    # Don&#39;t ignore .gitignore
    !.gitignore

    # Now exclude our type
    !*.foo

The problem with this solution is that **it stops tracking newly added files** (since `*` ignores all files). I don&#39;t want to keep excluding each and every file type. I want normal behaviour where if any new file is added, `git status` shows it. 

I finally got a solution [here][4]. The solution is to add another `.gitignore` file in `Resources` folder. This works correctly. 

Can I achieve the same with one ignore file? I find having many ignore files in different directories a bit clunky.

This is what I&#39;m trying to achieve: 

    # Ignore everything under Resources folder, not elsewhere
    Resources

    # Don&#39;t ignore directories, so we can recurse into them
    !*Resources/

    # Now exclude our type
    !*.foo

But this gives the opposite output. It ignores `*.foo` types and tracks other files.

  [1]: https://stackoverflow.com/questions/11852558/gitignore-only-allow-certain-extensions-and-files
  [2]: https://stackoverflow.com/questions/9049835/how-can-i-ignore-all-files-except-those-with-a-certain-extension-in-git
  [3]: https://stackoverflow.com/questions/8024924/gitignore-ignore-all-files-then-recursively-allow-foo
  [4]: https://stackoverflow.com/questions/7803689/gitignore-ignore-all-files-in-folder-hierachy-except-one-specific-filetype

Correctly ignore all files recursively under a specific folder except for a specific file type

Is there a simple way to move up one directory in python using a single line of code? Something similar to `cd ..` in command line

Moving up one directory in Python

I was hoping this would be a simple thing, but I cannot find anything out there to do so.

I just want to get all folders/directories within a given folder/directory.

So for example:

    &lt;MyFolder&gt;
    |- SomeFolder
    |- SomeOtherFolder
    |- SomeFile.txt
    |- SomeOtherFile.txt
    |- x-directory

I would expect to get an array of:

    [&quot;SomeFolder&quot;, &quot;SomeOtherFolder&quot;, &quot;x-directory&quot;]

Or the above with the path if that was how it was served...

So does anything already exist to do the above?

Get all directories within directory nodejs

I&#39;ve already read [this thread][1] but when I implement it into my code it only works for a few iterations. 

I&#39;m using python to iterate through a directory (lets call it move directory) to copy mainly pdf files (matching a unique ID) to another directory (base directory) to the matching folder (with the corresponding unique ID). I started using `shutil.copy` but if there are duplicates it overwrites the existing file. 

I&#39;d like to be able to search the corresponding folder to see if the file already exists, and iteratively name it if more than one occurs. 

e.g.

 - copy file 1234.pdf to folder in base directory 1234.
 - if 1234.pdf exists to name it 1234_1.pdf,
 - if another pdf is copied as 1234.pdf then it would be 1234_2.pdf.

Here is my code:

    import arcpy
    import os
    import re
    import sys
    import traceback
    import collections
    import shutil

    movdir = r&quot;C:\Scans&quot;
    basedir = r&quot;C:\Links&quot;

    try:
        #Walk through all files in the directory that contains the files to copy
        for root, dirs, files in os.walk(movdir):
            for filename in files:
                #find the name location and name of files
                path = os.path.join(root, filename)
                print path
                #file name and extension
                ARN, extension = os.path.splitext(filename)
                print ARN

                #Location of the corresponding folder in the new directory
                link = os.path.join(basedir,ARN)

                # if the folder already exists in new directory
                if os.path.exists(link):

                    #this is the file location in the new directory
                    file = os.path.join(basedir, ARN, ARN)
                    linkfn = os.path.join(basedir, ARN, filename)

                    if os.path.exists(linkfn):
                        i = 0
                        #if this file already exists in the folder
                        print &quot;Path exists already&quot;
                        while os.path.exists(file + &quot;_&quot; + str(i) + extension):
                            i+=1
                        print &quot;Already 2x exists...&quot;
                        print &quot;Renaming&quot;
                        shutil.copy(path, file + &quot;_&quot; + str(i) + extension)
                    else:

                        shutil.copy(path, link)
                        print ARN + &quot; &quot; +  &quot;Copied&quot;
                else:
                    print ARN + &quot; &quot; + &quot;Not Found&quot;

  [1]: https://stackoverflow.com/questions/10036489/copy-a-file-to-a-new-location-and-increment-filename-python

Content Type	Original Author	Original Content on Stackoverflow
Question	Nate Rubin	View Question on Stackoverflow
Solution 1 - Python	Dr. Jan-Philip Gehrcke	View Answer on Stackoverflow
Solution 2 - Python	scott_fakename	View Answer on Stackoverflow
Solution 3 - Python	Suresh Dooly	View Answer on Stackoverflow

Difference between os.path.exists and os.path.isfile?

Python Problem Overview

Python Solutions

Solution 1 - Python

Solution 2 - Python

Solution 3 - Python

What is -ffreestanding option in gcc?

Generic with multiple classes

Attributions