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NumPy: Array creation routines

Last update on May 28 2022 11:21:25 (UTC/GMT +8 hours)

Array creation routines

Name	Description	Syntax
Ones and zeros
empty()	Return a new array of given shape and type, without initializing entries.	empty(shape[, dtype, order])
empty_like	Return a new array with the same shape and type as a given array.	empty_like(a[, dtype, order, subok])
eye()	Return a 2-D array with ones on the diagonal and zeros elsewhere.	eye(N[, M, k, dtype])
identity()	Return the identity array.	identity(n[, dtype])
ones()	Return a new array of given shape and type, filled with ones.	ones(shape[, dtype, order])
ones_like	Return an array of ones with the same shape and type as a given array.	ones_like(a[, dtype, order, subok])
zeros	Return a new array of given shape and type, filled with zeros.	zeros(shape[, dtype, order])
zeros_like	Return an array of zeros with the same shape and type as a given array.	zeros_like(a[, dtype, order, subok])
full()	Return a new array of given shape and type, filled with fill_value.	full(shape, fill_value[, dtype, order])
full_like()	Return a full array with the same shape and type as a given array.	full_like(a, fill_value[, dtype, order, subok])

Pictorial Presentation: NumPy Array creation

NumPy: array creation

Name	Description	Syntax
From existing data
array()	Create an array.	array(object[, dtype, copy, order, subok, ndmin])
asarray()	Convert the input to an array.	asarray(a[, dtype, order])
asanyarray()	Convert the input to an ndarray, but pass ndarray subclasses through.	asanyarray(a[, dtype, order])
ascontiguousarray()	Return a contiguous array in memory (C order).	ascontiguousarray(a[, dtype])
asmatrix()	Interpret the input as a matrix.	asmatrix(data[, dtype])
copy()	Return an array copy of the given object.	copy(a[, order]
frombuffer()	Interpret a buffer as a 1-dimensional array.	frombuffer(buffer[, dtype, count, offset])
fromfile()	Construct an array from data in a text or binary file.	fromfile(file[, dtype, count, sep])
fromfunction()	Construct an array by executing a function over each coordinate.	fromfunction(function, shape, **kwargs)
fromiter()	Create a new 1-dimensional array from an iterable object.	fromiter(iterable, dtype[, count])
fromstring()	A new 1-D array initialized from raw binary or text data in a string.	fromstring(string[, dtype, count, sep])
loadtxt()	Load data from a text file.	loadtxt(fname[, dtype, comments, delimiter, ...])

Name	Description	Syntax
Creating record arrays (numpy.rec)
core.records.array()	Construct a record array from a wide-variety of objects.	core.defchararray.array(obj[, itemsize, ...])
core.records.fromarrays()	create a record array from a (flat) list of arrays	core.records.fromarrays(arrayList[, dtype, ...])
core.records.fromrecords()	create a recarray from a list of records in text form.	core.records.fromrecords(recList[, dtype, ...])
core.records.fromstring()	create a (read-only) record array from binary data contained in a string.	core.records.fromstring(datastring[, dtype, ...])
core.records.fromfile()	Create an array from binary file data.	core.records.fromfile(fd[, dtype, shape, ...])

Name	Description	Syntax
Creating character arrays (numpy.char)
core.defchararray.array()	Create a chararray.	core.defchararray.array(obj[, itemsize, ...])
core.defchararray.array()	Convert the input to a chararray, copying the data only if necessary.	core.defchararray.asarray(obj[, itemsize, ...])

Name	Description	Syntax
Numerical ranges
arange()	Return evenly spaced values within a given interval.	arange([start,] stop[, step,][, dtype])
linspace()	Return evenly spaced numbers over a specified interval.	linspace(start, stop[, num, endpoint, ...])
logspace()	Return numbers spaced evenly on a log scale.	logspace(start, stop[, num, endpoint, base, ...])
geomspace()	Return numbers spaced evenly on a log scale (a geometric progression).	geomspace(start, stop[, num, endpoint, dtype])
meshgrid()	Return coordinate matrices from coordinate vectors.	meshgrid(xi, *kwargs)
mgrid()	nd_grid instance which returns a dense multi-dimensional "meshgrid".	mgrid
ogrid()	nd_grid instance which returns an open multi-dimensional "meshgrid".	ogrid

Name	Description	Syntax
Building matrices
diag()	Extract a diagonal or construct a diagonal array.	diag(v[, k])
diagflat()	Create a two-dimensional array with the flattened input as a diagonal.	diagflat(v[, k])
tri()	An array with ones at and below the given diagonal and zeros elsewhere.	tri(N[, M, k, dtype])
tril()	Lower triangle of an array.	tril(m[, k])
triu()	Upper triangle of an array.	triu(m[, k])
vander()	Generate a Vandermonde matrix.	vander(x[, N, increasing])

Name	Description	Syntax
The Matrix class
mat()	Interpret the input as a matrix.	mat(data[, dtype])
bmat()	Build a matrix object from a string, nested sequence, or array.	bmat(obj[, ldict, gdict])

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