[Python] NumPy Library | NumPy 라이브러리

2022. 8. 15. 15:59

상단으로

NumPy Array Object	Description
The N-dimensional array (\(\texttt{numpy.ndarray}\))	- NumPy에서는 동일한 타입의 데이터를 담을 수 있는 N차원 배열 객체를 제공한다. - Python List보다 빠르고 메모리 효율적으로 동작한다.
Scalars	- NumPy에서는 Scientific Computing을 위한, Python Built-in Types보다 정교한 데이터 타입들을 제공한다. - CPython으로 구현되었다.
Data type objects (\(\texttt{numpy.dtype}\))	- NumPy array에 대해, 아래와 같은Meta Data를 제공한다: 1) Type of the data 2) Size of the data 3) Byte order of the data (Little-Endian or Big-Endian) 4) Meta data of structured data type (Field name, Field type, Memory size of each field) 5) Shape and type of sub-array 6) \(\texttt{datetime64}\) and \(\texttt{timedelta64}\)
Indexing routines	- NumPy에서는 NumPy array(Matrix)에 대해 다양한 Indexing을 수행할 수 있게 하는 함수들을 제공한다.
Iterating Over Arrays (\(\texttt{numpy.nditer}\))	- 하나 이상의 NumPy Array에 대한 Flexible한 Iteration을 제공한다.
Standard array subclasses	- \(\texttt{ndarray}\)는 상속되어 다양한 형태로 재정의될 수 있다. - NumPy에서는 \(\texttt{ndarray}\)를 상속받은 새로운 객체가 다른 array객체와 원활히 Interaction할 수 있도록 하는 여러 Tool들을 제공한다.
Masked arrays (\(\texttt{numpy.ma}\))	- Missing Entry 혹은 Invalid Entry를 위한 배열로, NumPy에서는 Masking 역할을 수행하는 배열 객체를 제공한다.
The array interface protocol (Array Protocol)	- array와 같은 Python Obejct들이 서로의 Data Buffer를 재사용할 수 있게 하는 프로토콜이다.
Datatimes and Timedeltas (\(\texttt{numpy.datetime64}\)) (\(\texttt{numpy.timedelta64}\))	- NumPy에서는 자체적으로 날짜 및 시간에 관련된 기능을 제공한다. - Python Standard Library에 이미 \(\texttt{datetime}\) 이름이 존재하기 때문에, NumPy에서는 \(\texttt{datetime64}\)로 정의되었다. - NumPy에서는 \(\texttt{timedelta64}\)를 통해 날짜 및 시간에 대해 연산을 가능하게 한다.

Attribute	Return Type	Description
T	ndarray	- The transposed array.
data	buffer	- Python buffer object pointing to the start of the array’s data.
dtype	dtype object	- Data-type of the array’s elements.
flags	dict	- Information about the memory layout of the array.
flat	numpy.flatiter object	- A 1-D iterator over the array.
imag	ndarray	- The imaginary part of the array.
real	ndarray	- The real part of the array.
size	int	- Number of elements in the array.
itemsize	int	- Length of one array element in bytes.
nbytes	int	- Total bytes consumed by the elements of the array.
ndim	int	- Number of array dimensions.
shape	tuple of ints	- Tuple of array dimensions.
strides	tuple of ints	- Tuple of bytes to step in each dimension when traversing an array.
ctypes	ctypes object	- An object to simplify the interaction of the array with the ctypes module.
base	ndarray	- Base object if memory is from some other object.

Method	Description
all()	- Returns True if all elements evaluate to True.
any()	- Returns True if any of the elements of a evaluate to True.
argmax()	- Return indices of the maximum values along the given axis.
argmin()	- Return indices of the minimum values along the given axis.
argpartition()	- Returns the indices that would partition this array.
argsort()	- Returns the indices that would sort this array.
astype()	- Copy of the array, cast to a specified type.
byteswap()	- Swap the bytes of the array elements
choose()	- Use an index array to construct a new array from a set of choices.
clip()	- Return an array whose values are limited to [min, max].
compress()	- Return selected slices of this array along given axis.
conj()	- Complex-conjugate all elements.
conjugate()	- Return the complex conjugate, element-wise.
copy()	- Return a copy of the array.
cumprod()	- Return the cumulative product of the elements along the given axis.
cumsum()	- Return the cumulative sum of the elements along the given axis.
diagonal()	- Return specified diagonals.
dump()	- Dump a pickle of the array to the specified file.
dumps()	- Returns the pickle of the array as a string.
fill()	- Fill the array with a scalar value.
flatten()	- Return a copy of the array collapsed into one dimension.
getfield()	- Returns a field of the given array as a certain type.
item()	- Copy an element of an array to a standard Python scalar and return it.
itemset()	- Insert scalar into an array (scalar is cast to array’s dtype, if possible)
max()	- Return the maximum along a given axis.
mean()	- Returns the average of the array elements along given axis.
min()	- Return the minimum along a given axis.
newbyteorder()	- Return the array with the same data viewed with a different byte order.
nonzero()	- Return the indices of the elements that are non-zero.
partition()	- Rearranges the elements in the array in such a way that the value of the element in kth position is in the position it would be in a sorted array.
prod()	- Return the product of the array elements over the given axis
ptp()	- Peak to peak (maximum - minimum) value along a given axis.
put()	- Set a.flat[n] = values[n] for all n in indices.
ravel()	- Return a flattened array.
repeat()	- Repeat elements of an array.
reshape()	- Returns an array containing the same data with a new shape.
resize()	- Change shape and size of array in-place.
round()	- Return a with each element rounded to the given number of decimals.
searchsorted()	- Find indices where elements of v should be inserted in a to maintain order.
setfield()	- Put a value into a specified place in a field defined by a data-type.
setflags()	- Set array flags WRITEABLE, ALIGNED, WRITEBACKIFCOPY, respectively.
sort()	- Sort an array in-place.
squeeze()	- Remove axes of length one from a.
std()	- Returns the standard deviation of the array elements along given axis.
sum()	- Return the sum of the array elements over the given axis.
swapaxes()	- Return a view of the array with axis1 and axis2 interchanged.
take()	- Return an array formed from the elements of a at the given indices.
tobytes()	- Construct Python bytes containing the raw data bytes in the array.
tofile()	- Write array to a file as text or binary (default).
tolist()	- Return the array as an a.ndim-levels deep nested list of Python scalars.
tostring()	- A compatibility alias for tobytes, with exactly the same behavior.
trace()	- Return the sum along diagonals of the array.
transpose()	- Returns a view of the array with axes transposed.
var()	- Returns the variance of the array elements, along given axis.
view()	- New view of array with the same data.

Category	Routine	Description
Array Creation from Shape or Value	empty()	Return a new array of given shape and type, without initializing entries.
	empty_like()	Return a new array with the same shape and type as a given array.
	eye()	Return a 2-D array with ones on the diagonal and zeros elsewhere.
	identify()	Return the identity array.
	ones()	Return a new array of given shape and type, filled with ones.
	ones_like()	Return an array of ones with the same shape and type as a given array.
	zeros()	Return a new array of given shape and type, filled with zeros.
	zeros_like()	Return an array of zeros with the same shape and type as a given array.
	full()	Return a new array of given shape and type, filled with fill_value.
	full_like()	Return a full array with the same shape and type as a given array.
Array Creation from Existing Data	array()	Create an array.
	asarray()	Convert the input to an array.
	asanyarray()	Convert the input to an ndarray, but pass ndarray subclasses through.
	ascontiguousarray()	Return a contiguous array (ndim >= 1) in memory (C order).
	asmatrix()	Interpret the input as a matrix.
	copy()	Return an array copy of the given object.
	frombuffer()	Interpret a buffer as a 1-dimensional array.
	from_dlpack()	Create a NumPy array from an object implementing the __dlpack__ protocol.
	fromfile()	Construct an array from data in a text or binary file.
	fromfunction()	Construct an array by executing a function over each coordinate.
	fromiter()	Create a new 1-dimensional array from an iterable object.
	fromstring()	A new 1-D array initialized from text data in a string.
	loadtxt()	Load data from a text file.
Record Array Creation (numpy.core.records)	core.records.array()	Construct a record array from a wide-variety of objects.
	core.records.fromarrays()	Create a record array from a (flat) list of arrays
	core.records.fromrecords()	Create a recarray from a list of records in text form.
	core.records.fromstring()	Create a record array from binary data
	core.records.fromfile()	Create an array from binary file data
Characters Array Creation (numpy.core.defchararray)	core.defchararray.array()	Create a chararray.
Characters Array Creation (numpy.core.defchararray)	core.defchararray.asarray()	Convert the input to a chararray, copying the data only if necessary.
Numerical Ranges	arange()	Return evenly spaced values within a given interval.
	linspace()	Return evenly spaced numbers over a specified interval.
	logspace()	Return numbers spaced evenly on a log scale.
	geomspace()	Return numbers spaced evenly on a log scale (a geometric progression).
	meshgrid()	Return coordinate matrices from coordinate vectors.
	mgrid()	nd_grid instance which returns a dense multi-dimensional ”meshgrid”.
	ogrid()	nd_grid instance which returns an open multidimensional ”meshgrid”.
Building Matirx	diag()	Extract a diagonal or construct a diagonal array.
	diagflat()	Create a two-dimensional array with the flattened input as a diagonal.
	tri()	An array with ones at and below the given diagonal and zeros elsewhere.
	tril()	Lower triangle of an array.
	triu()	Upper triangle of an array.
	vander()	Generate a Vandermonde matrix.
Matrix Class	mat()	Interpret the input as a matrix.
Matrix Class	bmat()	Build a matrix object from a string, nested sequence, or array.

Category	Routine	Description
Basic Operations	copyto()	Copies values from one array to another, broadcasting as necessary.
Basic Operations	shape()	Return the shape of an array.
Changing Array Shape	reshape()	Gives a new shape to an array without changing its data.
	ravel()	Return a contiguous flattened array.
	ndarray.flat	A 1-D iterator over the array.
	ndarray.flatten()	Return a copy of the array collapsed into one dimension.
Transpose-Like Operations	moveaxis()	Move axes of an array to new positions.
	rollaxis()	Roll the specified axis backwards, until it lies in a given position.
	swapaxes()	Interchange two axes of an array.
	ndarray.T	The transposed array.
	transpose()	Reverse or permute the axes of an array; returns the modified array.
Changing Number of Dimensions	atleast_1d()	Convert inputs to arrays with at least one dimension.
	atleast_2d()	View inputs as arrays with at least two dimensions.
	atleast_3d()	atleast_3d(*arys) View inputs as arrays with at least three dimensions.
	broadcast	broadcast Produce an object that mimics broadcasting.
	broadcast_to()	broadcast_to(array, shape[, subok]) Broadcast an array to a new shape.
	broadcast_arrays()	broadcast_arrays(*args[, subok]) Broadcast any number of arrays against each other.
	expand_dims()	expand_dims(a, axis) Expand the shape of an array.
	squeeze()	squeeze(a[, axis]) Remove axes of length one from a.
Changing kind of Array	asarray()	asarray(a[, dtype, order, like]) Convert the input to an array.
	asanyarray()	Convert the input to an ndarray, but pass ndarray subclasses through.
	asmatrix()	asmatrix(data[, dtype]) Interpret the input as a matrix.
	asfarray()	asfarray(a[, dtype]) Return an array converted to a float type.
	asfortranarray()	Return an array (ndim >= 1) laid out in Fortran order in memory.
	ascontiguousarray()	Return a contiguous array (ndim >= 1) in memory (C order).
	asarray_chkfinite()	asarray_chkfinite(a[, dtype, order]) Convert the input to an array, checking for NaNs or Infs.
	require()	Return an ndarray of the provided type that satisfies requirements.
Joining Arrays	concatenate()	Join a sequence of arrays along an existing axis.
	stack()	Join a sequence of arrays along a new axis.
	block()	Assemble an nd-array from nested lists of blocks.
	vstack()	Stack arrays in sequence vertically (row wise).
	hstack()	Stack arrays in sequence horizontally (column wise).
	dstack()	Stack arrays in sequence depth wise (along third axis).
	column_stack()	Stack 1-D arrays as columns into a 2-D array.
	row_stack()	Stack arrays in sequence vertically (row wise).
Splitting Arrays	split()	Split an array into multiple sub-arrays as views into ary.
	array_split()	Split an array into multiple sub-arrays.
	dsplit()	Split array into multiple sub-arrays along the 3rd axis (depth).
	hsplit()	Split an array into multiple sub-arrays horizontally (column-wise).
	vsplit()	Split an array into multiple sub-arrays vertically (rowwise).
Tiling Arrays	tile()	Construct an array by repeating A the number of times given by reps.
Tiling Arrays	repeat()	Repeat elements of an array.
Adding and Removing Elements	delete()	Return a new array with sub-arrays along an axis deleted.
	insert()	Insert values along the given axis before the given indices.
	append()	Append values to the end of an array.
	resize()	Return a new array with the specified shape.
	trim_zeros()	Trim the leading and/or trailing zeros from a 1-D array or sequence.
	unique()	Find the unique elements of an array.
Rearranging Elements	flip()	Reverse the order of elements in an array along the given axis.
	fliplr()	Reverse the order of elements along axis 1 (left/right).
	flipud()	Reverse the order of elements along axis 0 (up/down).
	reshape()	Gives a new shape to an array without changing its data.
	roll()	Roll array elements along a given axis.
	rot90()	Rotate an array by 90 degrees in the plane specified by axes.

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