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author | Stefan van der Walt <stefan@sun.ac.za> | 2008-08-23 23:17:23 +0000 |
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committer | Stefan van der Walt <stefan@sun.ac.za> | 2008-08-23 23:17:23 +0000 |
commit | 5c86844c34674e3d580ac2cd12ef171e18130b13 (patch) | |
tree | 2fdf1150706c07c7e193eb7483ce58a5074e5774 /numpy/doc/reference/glossary.py | |
parent | 376d483d31c4c5427510cf3a8c69fc795aef63aa (diff) | |
download | numpy-5c86844c34674e3d580ac2cd12ef171e18130b13.tar.gz |
Move documentation outside of source tree. Remove `doc` import from __init__.
Diffstat (limited to 'numpy/doc/reference/glossary.py')
-rw-r--r-- | numpy/doc/reference/glossary.py | 367 |
1 files changed, 0 insertions, 367 deletions
diff --git a/numpy/doc/reference/glossary.py b/numpy/doc/reference/glossary.py deleted file mode 100644 index 6a182adf4..000000000 --- a/numpy/doc/reference/glossary.py +++ /dev/null @@ -1,367 +0,0 @@ -""" -================= -Glossary -================= - -along an axis - Axes are defined for arrays with more than one dimension. A - 2-dimensional array has two corresponding axes: the first running - vertically downwards across rows (axis 0), and the second running - horizontally across columns (axis 1). - - Many operation can take place along one of these axes. For example, - we can sum each row of an array, in which case we operate along - columns, or axis 1:: - - >>> x = np.arange(12).reshape((3,4)) - - >>> x - array([[ 0, 1, 2, 3], - [ 4, 5, 6, 7], - [ 8, 9, 10, 11]]) - - >>> x.sum(axis=1) - array([ 6, 22, 38]) - -array or ndarray - A homogeneous container of numerical elements. Each element in the - array occupies a fixed amount of memory (hence homogeneous), and - can be a numerical element of a single type (such as float, int - or complex) or a combination (such as ``(float, int, float)``). Each - array has an associated data-type (or ``dtype``), which describes - the numerical type of its elements:: - - >>> x = np.array([1, 2, 3], float) - - >>> x - array([ 1., 2., 3.]) - - >>> x.dtype # floating point number, 64 bits of memory per element - dtype('float64') - - - # More complicated data type: each array element is a combination of - # and integer and a floating point number - >>> np.array([(1, 2.0), (3, 4.0)], dtype=[('x', int), ('y', float)]) - array([(1, 2.0), (3, 4.0)], - dtype=[('x', '<i4'), ('y', '<f8')]) - - Fast element-wise operations, called `ufuncs`_, operate on arrays. - -array_like - Any sequence that can be interpreted as an ndarray. This includes - nested lists, tuples, scalars and existing arrays. - -attribute - A property of an object that can be accessed using ``obj.attribute``, - e.g., ``shape`` is an attribute of an array:: - - >>> x = np.array([1, 2, 3]) - >>> x.shape - (3,) - -broadcast - NumPy can do operations on arrays whose shapes are mismatched:: - - >>> x = np.array([1, 2]) - >>> y = np.array([[3], [4]]) - - >>> x - array([1, 2]) - - >>> y - array([[3], - [4]]) - - >>> x + y - array([[4, 5], - [5, 6]]) - - See `doc.broadcasting`_ for more information. - -decorator - An operator that transforms a function. For example, a ``log`` - decorator may be defined to print debugging information upon - function execution:: - - >>> def log(f): - ... def new_logging_func(*args, **kwargs): - ... print "Logging call with parameters:", args, kwargs - ... return f(*args, **kwargs) - ... - ... return new_logging_func - - Now, when we define a function, we can "decorate" it using ``log``:: - - >>> @log - ... def add(a, b): - ... return a + b - - Calling ``add`` then yields: - - >>> add(1, 2) - Logging call with parameters: (1, 2) {} - 3 - -dictionary - Resembling a language dictionary, which provides a mapping between - words and descriptions thereof, a Python dictionary is a mapping - between two objects:: - - >>> x = {1: 'one', 'two': [1, 2]} - - Here, `x` is a dictionary mapping keys to values, in this case - the integer 1 to the string "one", and the string "two" to - the list ``[1, 2]``. The values may be accessed using their - corresponding keys:: - - >>> x[1] - 'one' - - >>> x['two'] - [1, 2] - - Note that dictionaries are not stored in any specific order. Also, - most mutable (see *immutable* below) objects, such as lists, may not - be used as keys. - - For more information on dictionaries, read the - `Python tutorial <http://docs.python.org/tut>`_. - -immutable - An object that cannot be modified after execution is called - immutable. Two common examples are strings and tuples. - -instance - A class definition gives the blueprint for constructing an object:: - - >>> class House(object): - ... wall_colour = 'white' - - Yet, we have to *build* a house before it exists:: - - >>> h = House() # build a house - - Now, ``h`` is called a ``House`` instance. An instance is therefore - a specific realisation of a class. - -iterable - A sequence that allows "walking" (iterating) over items, typically - using a loop such as:: - - >>> x = [1, 2, 3] - >>> [item**2 for item in x] - [1, 4, 9] - - It is often used in combintion with ``enumerate``:: - - >>> for n, k in enumerate(keys): - ... print "Key %d: %s" % (n, k) - ... - Key 0: a - Key 1: b - Key 2: c - -list - A Python container that can hold any number of objects or items. - The items do not have to be of the same type, and can even be - lists themselves:: - - >>> x = [2, 2.0, "two", [2, 2.0]] - - The list `x` contains 4 items, each which can be accessed individually:: - - >>> x[2] # the string 'two' - 'two' - - >>> x[3] # a list, containing an integer 2 and a float 2.0 - [2, 2.0] - - It is also possible to select more than one item at a time, - using *slicing*:: - - >>> x[0:2] # or, equivalently, x[:2] - [2, 2.0] - - In code, arrays are often conveniently expressed as nested lists:: - - - >>> np.array([[1, 2], [3, 4]]) - array([[1, 2], - [3, 4]]) - - For more information, read the section on lists in the `Python - tutorial <http://docs.python.org/tut>`_. For a mapping - type (key-value), see *dictionary*. - -mask - A boolean array, used to select only certain elements for an operation:: - - >>> x = np.arange(5) - >>> x - array([0, 1, 2, 3, 4]) - - >>> mask = (x > 2) - >>> mask - array([False, False, False, True, True], dtype=bool) - - >>> x[mask] = -1 - >>> x - array([ 0, 1, 2, -1, -1]) - -masked array - Array that suppressed values indicated by a mask:: - - >>> x = np.ma.masked_array([np.nan, 2, np.nan], [True, False, True]) - >>> x - masked_array(data = [-- 2.0 --], - mask = [ True False True], - fill_value=1e+20) - - >>> x + [1, 2, 3] - masked_array(data = [-- 4.0 --], - mask = [ True False True], - fill_value=1e+20) - - Masked arrays are often used when operating on arrays containing - missing or invalid entries. - -matrix - A 2-dimensional ndarray that preserves its two-dimensional nature - throughout operations. It has certain special operations, such as ``*`` - (matrix multiplication) and ``**`` (matrix power), defined:: - - >>> x = np.mat([[1, 2], [3, 4]]) - - >>> x - matrix([[1, 2], - [3, 4]]) - - >>> x**2 - matrix([[ 7, 10], - [15, 22]]) - -method - A function associated with an object. For example, each ndarray has a - method called ``repeat``:: - - >>> x = np.array([1, 2, 3]) - - >>> x.repeat(2) - array([1, 1, 2, 2, 3, 3]) - -reference - If ``a`` is a reference to ``b``, then ``(a is b) == True``. Therefore, - ``a`` and ``b`` are different names for the same Python object. - -self - Often seen in method signatures, ``self`` refers to the instance - of the associated class. For example: - - >>> class Paintbrush(object): - ... color = 'blue' - ... - ... def paint(self): - ... print "Painting the city %s!" % self.color - ... - >>> p = Paintbrush() - >>> p.color = 'red' - >>> p.paint() # self refers to 'p' - Painting the city red! - -slice - Used to select only certain elements from a sequence:: - - >>> x = range(5) - >>> x - [0, 1, 2, 3, 4] - - >>> x[1:3] # slice from 1 to 3 (excluding 3 itself) - [1, 2] - - >>> x[1:5:2] # slice from 1 to 5, but skipping every second element - [1, 3] - - >>> x[::-1] # slice a sequence in reverse - [4, 3, 2, 1, 0] - - Arrays may have more than one dimension, each which can be sliced - individually:: - - >>> x = np.array([[1, 2], [3, 4]]) - >>> x - array([[1, 2], - [3, 4]]) - - >>> x[:, 1] - array([2, 4]) - -tuple - A sequence that may contain a variable number of types of any - kind. A tuple is immutable, i.e., once constructed it cannot be - changed. Similar to a list, it can be indexed and sliced:: - - >>> x = (1, 'one', [1, 2]) - - >>> x - (1, 'one', [1, 2]) - - >>> x[0] - 1 - - >>> x[:2] - (1, 'one') - - A useful concept is "tuple unpacking", which allows variables to - be assigned to the contents of a tuple:: - - >>> x, y = (1, 2) - >>> x, y = 1, 2 - - This is often used when a function returns multiple values: - - >>> def return_many(): - ... return 1, 'alpha' - - >>> a, b, c = return_many() - >>> a, b, c - (1, 'alpha', None) - - >>> a - 1 - >>> b - 'alpha' - -ufunc - Universal function. A fast element-wise array operation. Examples include - ``add``, ``sin`` and ``logical_or``. - -view - An array that does not own its data, but refers to another array's - data instead. For example, we may create a view that only shows - every second element of another array:: - - >>> x = np.arange(5) - >>> x - array([0, 1, 2, 3, 4]) - - >>> y = x[::2] - >>> y - array([0, 2, 4]) - - >>> x[0] = 3 # changing x changes y as well, since y is a view on x - >>> y - array([3, 2, 4]) - -wrapper - Python is a high-level (highly abstracted, or English-like) language. - This abstraction comes at a price in execution speed, and sometimes - it becomes necessary to use lower level languages to do fast - computations. A wrapper is code that provides a bridge between - high and the low level languages, allowing, e.g., Python to execute - code written in C or Fortran. - - Examples include ctypes, SWIG and Cython (which wraps C and C++) - and f2py (which wraps Fortran). - -""" |