class numpy.ndarray(shape, dtype=float, buffer=None, offset=0, strides=None, order=None)
[source]
An array object represents a multidimensional, homogeneous array of fixedsize items. An associated datatype object describes the format of each element in the array (its byteorder, how many bytes it occupies in memory, whether it is an integer, a floating point number, or something else, etc.)
Arrays should be constructed using array
, zeros
or empty
(refer to the See Also section below). The parameters given here refer to a lowlevel method (ndarray(…)
) for instantiating an array.
For more information, refer to the numpy
module and examine the methods and attributes of an array.
Parameters: 


See also
There are two modes of creating an array using __new__
:
buffer
is None, then only shape
, dtype
, and order
are used.buffer
is an object exposing the buffer interface, then all keywords are interpreted.No __init__
method is needed because the array is fully initialized after the __new__
method.
These examples illustrate the lowlevel ndarray
constructor. Refer to the See Also
section above for easier ways of constructing an ndarray.
First mode, buffer
is None:
>>> np.ndarray(shape=(2,2), dtype=float, order='F') array([[0.0e+000, 0.0e+000], # random [ nan, 2.5e323]])
Second mode:
>>> np.ndarray((2,), buffer=np.array([1,2,3]), ... offset=np.int_().itemsize, ... dtype=int) # offset = 1*itemsize, i.e. skip first element array([2, 3])
Attributes: 


all ([axis, out, keepdims])  Returns True if all elements evaluate to True. 
any ([axis, out, keepdims])  Returns True if any of the elements of a evaluate to True. 
argmax ([axis, out])  Return indices of the maximum values along the given axis. 
argmin ([axis, out])  Return indices of the minimum values along the given axis of a . 
argpartition (kth[, axis, kind, order])  Returns the indices that would partition this array. 
argsort ([axis, kind, order])  Returns the indices that would sort this array. 
astype (dtype[, order, casting, subok, copy])  Copy of the array, cast to a specified type. 
byteswap ([inplace])  Swap the bytes of the array elements 
choose (choices[, out, mode])  Use an index array to construct a new array from a set of choices. 
clip ([min, max, out])  Return an array whose values are limited to [min, max] . 
compress (condition[, axis, out])  Return selected slices of this array along given axis. 
conj ()  Complexconjugate all elements. 
conjugate ()  Return the complex conjugate, elementwise. 
copy ([order])  Return a copy of the array. 
cumprod ([axis, dtype, out])  Return the cumulative product of the elements along the given axis. 
cumsum ([axis, dtype, out])  Return the cumulative sum of the elements along the given axis. 
diagonal ([offset, axis1, axis2])  Return specified diagonals. 
dot (b[, out])  Dot product of two arrays. 
dump (file)  Dump a pickle of the array to the specified file. 
dumps ()  Returns the pickle of the array as a string. 
fill (value)  Fill the array with a scalar value. 
flatten ([order])  Return a copy of the array collapsed into one dimension. 
getfield (dtype[, offset])  Returns a field of the given array as a certain type. 
item (*args)  Copy an element of an array to a standard Python scalar and return it. 
itemset (*args)  Insert scalar into an array (scalar is cast to array’s dtype, if possible) 
max ([axis, out, keepdims, initial, where])  Return the maximum along a given axis. 
mean ([axis, dtype, out, keepdims])  Returns the average of the array elements along given axis. 
min ([axis, out, keepdims, initial, where])  Return the minimum along a given axis. 
newbyteorder ([new_order])  Return the array with the same data viewed with a different byte order. 
nonzero ()  Return the indices of the elements that are nonzero. 
partition (kth[, axis, kind, order])  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 ([axis, dtype, out, keepdims, initial, …])  Return the product of the array elements over the given axis 
ptp ([axis, out, keepdims])  Peak to peak (maximum  minimum) value along a given axis. 
put (indices, values[, mode])  Set a.flat[n] = values[n] for all n in indices. 
ravel ([order])  Return a flattened array. 
repeat (repeats[, axis])  Repeat elements of an array. 
reshape (shape[, order])  Returns an array containing the same data with a new shape. 
resize (new_shape[, refcheck])  Change shape and size of array inplace. 
round ([decimals, out])  Return a with each element rounded to the given number of decimals. 
searchsorted (v[, side, sorter])  Find indices where elements of v should be inserted in a to maintain order. 
setfield (val, dtype[, offset])  Put a value into a specified place in a field defined by a datatype. 
setflags ([write, align, uic])  Set array flags WRITEABLE, ALIGNED, (WRITEBACKIFCOPY and UPDATEIFCOPY), respectively. 
sort ([axis, kind, order])  Sort an array inplace. 
squeeze ([axis])  Remove singledimensional entries from the shape of a . 
std ([axis, dtype, out, ddof, keepdims])  Returns the standard deviation of the array elements along given axis. 
sum ([axis, dtype, out, keepdims, initial, where])  Return the sum of the array elements over the given axis. 
swapaxes (axis1, axis2)  Return a view of the array with axis1 and axis2 interchanged. 
take (indices[, axis, out, mode])  Return an array formed from the elements of a at the given indices. 
tobytes ([order])  Construct Python bytes containing the raw data bytes in the array. 
tofile (fid[, sep, format])  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 ([order])  Construct Python bytes containing the raw data bytes in the array. 
trace ([offset, axis1, axis2, dtype, out])  Return the sum along diagonals of the array. 
transpose (*axes)  Returns a view of the array with axes transposed. 
var ([axis, dtype, out, ddof, keepdims])  Returns the variance of the array elements, along given axis. 
view ([dtype, type])  New view of array with the same data. 
© 2005–2019 NumPy Developers
Licensed under the 3clause BSD License.
https://docs.scipy.org/doc/numpy1.17.0/reference/generated/numpy.ndarray.html