# NumPy: Array creation routines

## Array creation routines

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

Pictorial Presentation: NumPy Array creation

Name Description Syntax From existing data array() Create an array. numpy.array(object[, dtype, copy, order, subok, ndmin]) asarray() Convert the input to an array. numpy.asarray(a[, dtype, order]) asanyarray() Convert the input to an ndarray, but pass ndarray subclasses through. numpy.asanyarray(a[, dtype, order]) ascontiguousarray() Return a contiguous array in memory (C order). numpy.ascontiguousarray(a[, dtype]) asmatrix() Interpret the input as a matrix. numpy.asmatrix(data[, dtype]) copy() Return an array copy of the given object. numpy.copy(a[, order] frombuffer() Interpret a buffer as a 1-dimensional array. numpy.frombuffer(buffer[, dtype, count, offset]) fromfile() Construct an array from data in a text or binary file. numpy.fromfile(file[, dtype, count, sep]) fromfunction() Construct an array by executing a function over each coordinate. numpy.fromfunction(function, shape, **kwargs) fromiter() Create a new 1-dimensional array from an iterable object. numpy.fromiter(iterable, dtype[, count]) fromstring() A new 1-D array initialized from raw binary or text data in a string. numpy.fromstring(string[, dtype, count, sep]) loadtxt() Load data from a text file. numpy.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. numpy.arange([start,] stop[, step,][, dtype]) linspace() Return evenly spaced numbers over a specified interval. numpy.linspace(start, stop[, num, endpoint, ...]) logspace() Return numbers spaced evenly on a log scale. numpy.logspace(start, stop[, num, endpoint, base, ...]) geomspace() Return numbers spaced evenly on a log scale (a geometric progression). numpy.geomspace(start, stop[, num, endpoint, dtype]) meshgrid() Return coordinate matrices from coordinate vectors. numpy.meshgrid(*xi, **kwargs) mgrid() nd_grid instance which returns a dense multi-dimensional "meshgrid". numpy.mgrid ogrid() nd_grid instance which returns an open multi-dimensional "meshgrid". numpy.ogrid
Name Description Syntax Building matrices diag() Extract a diagonal or construct a diagonal array. numpy.diag(v[, k]) diagflat() Create a two-dimensional array with the flattened input as a diagonal. numpy.diagflat(v[, k]) tri() An array with ones at and below the given diagonal and zeros elsewhere. numpy.tri(N[, M, k, dtype]) tril() Lower triangle of an array. numpy.tril(m[, k]) triu() Upper triangle of an array. numpy.triu(m[, k]) vander() Generate a Vandermonde matrix. numpy.vander(x[, N, increasing])
Name Description Syntax The Matrix class mat() Interpret the input as a matrix. numpy.mat(data[, dtype]) bmat() Build a matrix object from a string, nested sequence, or array. numpy.bmat(obj[, ldict, gdict])

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