Array creation routines

See also

Array creation

Ones and zeros

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

From existing data

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

Creating record arrays (numpy.rec)


numpy.rec is the preferred alias for numpy.core.records.

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

Creating character arrays (numpy.char)


numpy.char is the preferred alias for numpy.core.defchararray.

core.defchararray.array(obj[, itemsize, ...]) Create a chararray.
core.defchararray.asarray(obj[, itemsize, ...]) Convert the input to a chararray, copying the data only if necessary.

Numerical ranges

arange([start,] stop[, step,][, dtype]) Return evenly spaced values within a given interval.
linspace(start, stop[, num, endpoint, retstep]) Return evenly spaced numbers over a specified interval.
logspace(start, stop[, num, endpoint, base]) Return numbers spaced evenly on a log scale.
meshgrid(x, y) Return coordinate matrices from two coordinate vectors.
mgrid nd_grid instance which returns a dense multi-dimensional “meshgrid”.
ogrid nd_grid instance which returns an open multi-dimensional “meshgrid”.

Building matrices

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

The Matrix class

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