# Array creation routines¶

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(a[, dtype, order, subok]) Return 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. full(shape, fill_value[, dtype, order]) Return a new array of given shape and type, filled with fill_value. full_like(a, fill_value[, dtype, order, subok]) Return a full array 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[, order]) 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)¶

Note

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 If file is a string then that file is opened, else it is assumed to be a file object.

## Creating character arrays (numpy.char)¶

Note

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, ...]) Return evenly spaced numbers over a specified interval. logspace(start, stop[, num, endpoint, base, ...]) Return numbers spaced evenly on a log scale. meshgrid(*xi, **kwargs) 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 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, increasing]) Generate a Vandermonde 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.