Python equivalent which

Operations on the 2D instances of these arrays are modeled on matrix operations in linear algebra. In NumPy, the basic type is a multidimensional array. Array assignments in NumPy are usually stored as n-dimensional arrays with the minimum type required to hold the objects in sequence, unless you specify the number of dimensions and type.

The operator, available since Python 3. NumPy, like Python, numbers indices from 0; a[0] is the first element. NumPy is based on Python, a general-purpose language. In addition, Python is often embedded as a scripting language in other software, allowing NumPy to be used there too.

MATLAB array slicing uses pass-by-value semantics, with a lazy copy-on-write scheme to prevent creating copies until they are needed. Slicing operations copy parts of the array. NumPy array slicing uses pass-by-reference, that does not copy the arguments. Slicing operations are views into an array. These are similar expressions, not equivalents. For details, see the documentation. Note: When saving arrays to data. The first through third rows and fifth through ninth columns of a 2D array, a.

The NumPy result is an array of the boolean values False and True. Solve a. T instead. Fourier transform of a. The list is in arbitrary order, and does not include the special entries '. If a file is removed from or added to the directory during the call of this function, whether a name for that file be included is unspecified.

If path is of type bytes directly or indirectly through the PathLike interface , the filenames returned will also be of type bytes ; in all other circumstances, they will be of type str. This function can also support specifying a file descriptor ; the file descriptor must refer to a directory. To encode str filenames to bytes , use fsencode.

The scandir function returns directory entries along with file attribute information, giving better performance for many common use cases. Perform the equivalent of an lstat system call on the given path. Similar to stat , but does not follow symbolic links. On platforms that do not support symbolic links, this is an alias for stat. This function can also support paths relative to directory descriptors. Other kinds of reparse points are resolved by the operating system as for stat.

If the directory already exists, FileExistsError is raised. On some systems, mode is ignored. Where it is used, the current umask value is first masked out. If bits other than the last 9 i. On some platforms, they are ignored and you should call chmod explicitly to set them. Recursive directory creation function. Like mkdir , but makes all intermediate-level directories needed to contain the leaf directory. The mode parameter is passed to mkdir for creating the leaf directory; see the mkdir description for how it is interpreted.

To set the file permission bits of any newly-created parent directories you can set the umask before invoking makedirs. The file permission bits of existing parent directories are not changed. Since this behavior was impossible to implement safely, it was removed in Python 3.

See bpo Create a FIFO a named pipe named path with numeric mode mode. The current umask value is first masked out from the mode. FIFOs are pipes that can be accessed like regular files. FIFOs exist until they are deleted for example with os.

Create a filesystem node file, device special file or named pipe named path. For stat. Return system configuration information relevant to a named file. Dictionary mapping names accepted by pathconf and fpathconf to the integer values defined for those names by the host operating system.

This can be used to determine the set of names known to the system. Return a string representing the path to which the symbolic link points. The result may be either an absolute or relative pathname; if it is relative, it may be converted to an absolute pathname using os. If the path is a string object directly or indirectly through a PathLike interface , the result will also be a string object, and the call may raise a UnicodeDecodeError. If the path is a bytes object direct or indirectly , the result will be a bytes object.

When trying to resolve a path that may contain links, use realpath to properly handle recursion and platform differences.

Remove delete the file path. If path is a directory, an IsADirectoryError is raised. Use rmdir to remove directories. If the file does not exist, a FileNotFoundError is raised. This function can support paths relative to directory descriptors. On Windows, attempting to remove a file that is in use causes an exception to be raised; on Unix, the directory entry is removed but the storage allocated to the file is not made available until the original file is no longer in use.

This function is semantically identical to unlink. Remove directories recursively. Works like rmdir except that, if the leaf directory is successfully removed, removedirs tries to successively remove every parent directory mentioned in path until an error is raised which is ignored, because it generally means that a parent directory is not empty.

For example, os. Raises OSError if the leaf directory could not be successfully removed. Rename the file or directory src to dst. If dst exists, the operation will fail with an OSError subclass in a number of cases:.

On Windows, if dst exists a FileExistsError is always raised. If both are directories and dst is empty, dst will be silently replaced. If dst is a non-empty directory, an OSError is raised. If both are files, dst it will be replaced silently if the user has permission. The operation may fail on some Unix flavors if src and dst are on different filesystems. If you want cross-platform overwriting of the destination, use replace. Recursive directory or file renaming function.

Works like rename , except creation of any intermediate directories needed to make the new pathname good is attempted first. After the rename, directories corresponding to rightmost path segments of the old name will be pruned away using removedirs. This function can fail with the new directory structure made if you lack permissions needed to remove the leaf directory or file. If dst is a directory, OSError will be raised. If dst exists and is a file, it will be replaced silently if the user has permission.

The operation may fail if src and dst are on different filesystems. Remove delete the directory path. In order to remove whole directory trees, shutil. Return an iterator of os. DirEntry objects corresponding to the entries in the directory given by path. The entries are yielded in arbitrary order, and the special entries '. If a file is removed from or added to the directory after creating the iterator, whether an entry for that file be included is unspecified.

Using scandir instead of listdir can significantly increase the performance of code that also needs file type or file attribute information, because os.

DirEntry objects expose this information if the operating system provides it when scanning a directory. All os. If path is of type bytes directly or indirectly through the PathLike interface , the type of the name and path attributes of each os. DirEntry will be bytes ; in all other circumstances, they will be of type str. The scandir iterator supports the context manager protocol and has the following method:. This is called automatically when the iterator is exhausted or garbage collected, or when an error happens during iterating.

However it is advisable to call it explicitly or use the with statement. The entry. If a scandir iterator is neither exhausted nor explicitly closed a ResourceWarning will be emitted in its destructor.

The function accepts a path-like object. Object yielded by scandir to expose the file path and other file attributes of a directory entry. When a stat or lstat system call is made, the os.

DirEntry object will cache the result. DirEntry instances are not intended to be stored in long-lived data structures; if you know the file metadata has changed or if a long time has elapsed since calling scandir , call os. Because the os. DirEntry methods can make operating system calls, they may also raise OSError. If you need very fine-grained control over errors, you can catch OSError when calling one of the os.

DirEntry methods and handle as appropriate. To be directly usable as a path-like object , os. DirEntry implements the PathLike interface. Attributes and methods on a os.

DirEntry instance are as follows:. The name attribute will be bytes if the scandir path argument is of type bytes and str otherwise. Use fsdecode to decode byte filenames. The path is only absolute if the scandir path argument was absolute. If the scandir path argument was a file descriptor , the path attribute is the same as the name attribute. The path attribute will be bytes if the scandir path argument is of type bytes and str otherwise. The result is cached on the os. DirEntry object.

Call os. On the first, uncached call, no system call is required in most cases. Specifically, for non-symlinks, neither Windows or Unix require a system call, except on certain Unix file systems, such as network file systems, that return dirent.

Specifically, neither Windows or Unix require a system call, except on certain Unix file systems, such as network file systems, that return dirent. On Unix, this method always requires a system call. Note that there is a nice correspondence between several attributes and methods of os. DirEntry and of pathlib. Added support for bytes paths on Windows. Get the status of a file or a file descriptor. Perform the equivalent of a stat system call on the given path. This function can support specifying a file descriptor and not following symlinks.

Other types of reparse points that do not resemble links or that the operating system is unable to follow will be opened directly. When following a chain of multiple links, this may result in the original link being returned instead of the non-link that prevented full traversal. To obtain stat results for the final path in this case, use the os. This does not apply to dangling symlinks or junction points, which will raise the usual exceptions.

Object whose attributes correspond roughly to the members of the stat structure. It is used for the result of os. Size of the file in bytes, if it is a regular file or a symbolic link. The size of a symbolic link is the length of the pathname it contains, without a terminating null byte.

See your operating system documentation for details. Number of byte blocks allocated for file. Writing to a file in smaller chunks may cause an inefficient read-modify-rewrite. On other Unix systems such as FreeBSD , the following attributes may be available but may be only filled out if root tries to use them :. The standard module stat defines functions and constants that are useful for extracting information from a stat structure.

On Windows, some items are filled with dummy values. More items may be added at the end by some implementations. Perform a statvfs system call on the given path. As an example, this expression evaluates to True if os. A set object indicating whether os. If the local platform supports it, the collection will contain os.

This expression evaluates to True if os. A set object indicating which functions in the os module permit specifying their path parameter as an open file descriptor on the local platform.

Different platforms provide different features, and the underlying functionality Python uses to accept open file descriptors as path arguments is not available on all platforms Python supports. On Windows, a symlink represents either a file or a directory, and does not morph to the target dynamically.

If the target is present, the type of the symlink will be created to match. On newer versions of Windows 10, unprivileged accounts can create symlinks if Developer Mode is enabled. OSError is raised when the function is called by an unprivileged user. Truncate the file corresponding to path , so that it is at most length bytes in size.

This function is semantically identical to remove ; the unlink name is its traditional Unix name. Please see the documentation for remove for further information. These specify the times set on path and are used as follows:. If times is not None , it must be a 2-tuple of the form atime, mtime where each member is an int or float expressing seconds.

Note that the exact times you set here may not be returned by a subsequent stat call, depending on the resolution with which your operating system records access and modification times; see stat. Generate the file names in a directory tree by walking the tree either top-down or bottom-up. For each directory in the tree rooted at directory top including top itself , it yields a 3-tuple dirpath, dirnames, filenames. Note that the names in the lists contain no path components.

To get a full path which begins with top to a file or directory in dirpath , do os. Whether or not the lists are sorted depends on the file system. If a file is removed from or added to the dirpath directory during generating the lists, whether a name for that file be included is unspecified.

If optional argument topdown is True or not specified, the triple for a directory is generated before the triples for any of its subdirectories directories are generated top-down. If topdown is False , the triple for a directory is generated after the triples for all of its subdirectories directories are generated bottom-up.

No matter the value of topdown , the list of subdirectories is retrieved before the tuples for the directory and its subdirectories are generated. When topdown is True , the caller can modify the dirnames list in-place perhaps using del or slice assignment , and walk will only recurse into the subdirectories whose names remain in dirnames ; this can be used to prune the search, impose a specific order of visiting, or even to inform walk about directories the caller creates or renames before it resumes walk again.

Modifying dirnames when topdown is False has no effect on the behavior of the walk, because in bottom-up mode the directories in dirnames are generated before dirpath itself is generated. By default, errors from the scandir call are ignored. If optional argument onerror is specified, it should be a function; it will be called with one argument, an OSError instance. It can report the error to continue with the walk, or raise the exception to abort the walk.

Note that the filename is available as the filename attribute of the exception object. By default, walk will not walk down into symbolic links that resolve to directories. Set followlinks to True to visit directories pointed to by symlinks, on systems that support them.

Improve this answer. Netwave Netwave 28k 5 5 gold badges 34 34 silver badges 65 65 bronze badges. I like your comparisson between R and Python, this is very usefule for expert R's users but beginner Python's users like me — Henry Navarro.

Hadij 1, 3 3 gold badges 18 18 silver badges 35 35 bronze badges. Ram Prajapati Ram Prajapati 1, 5 5 silver badges 8 8 bronze badges. It works for pandas. Karl Anka Karl Anka 2, 13 13 silver badges 27 27 bronze badges.

Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Put another way, is there a cross-platform way of knowing which file will be executed by subprocess. Popen file without first executing it? Python 3. Return the path to an executable which would be run if the given cmd was called. If no cmd would be called, return None. Defaults to os. Returns the complete path to 'executable' or None if not found. You may want to call os. Popen will be able to execute the file.

Also of note, shutil. It is available for installation via the aforementioned GitHub page i.