Numpy array dimensions

Question

I m currently trying to learn Numpy and Python  Given the following array   import numpy as np a   np array   1 2   1 2      Is there a function that returns the dimensions of a  e g a is a 2 by 2 array    size   returns 4 and that doesn t help very much

User · Answer

rows   a shape 0    2  cols   a shape 1    2 a shape   2 2  a size   rows   cols   4

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a shape is just a limited version of np info    Check this out   import numpy as np a   np array   1 2   1 2    np info a    Out  class   ndarray shape    2  2  strides    8  4  itemsize   4 aligned   True contiguous   True fortran   False data pointer  0x27509cf0560 byteorder   little byteswap   False type  int32

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First   By convention  in Python world  the shortcut for numpy is np  so   In  1   import numpy as np  In  2   a   np array   1 2   3 4      Second   In Numpy  dimension  axis axes  shape are related and sometimes similar concepts   dimension  In Mathematics Physics  dimension or dimensionality is informally defined as the minimum number of coordinates needed to specify any point within a space  But in Numpy  according to the numpy doc  it s the same as axis axes      In Numpy dimensions are called axes  The number of axes is rank    In  3   a ndim    num of dimensions axes   Mathematics definition of dimension  Out 3   2   axis axes  the nth coordinate to index an array in Numpy  And multidimensional arrays can have one index per axis   In  4   a 1 0     to index  a   we specific 1 at the first axis and 0 at the second axis  Out 4   3    which results in 3  locate at the row 1 and column 0  0-based index    shape  describes how many data  or the range  along each available axis   In  5   a shape Out 5    2  2     both the first and second axis have 2  columns rows pages blocks      data

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You can use  shape  In  a   np array   1 2 3   4 5 6    In  a shape Out   2  3  In  a shape 0    x axis Out  2 In  a shape 1    y axis Out  3

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The shape method requires that a be a Numpy ndarray  But Numpy can also calculate the shape of iterables of pure python objects   np shape   1 2   1 2

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You can use  ndim for dimension and  shape to know the exact dimension  var   np array   1 2 3 4 5 6    1 2 3 4 5 6     var ndim   displays 2  var shape   display 6  2   You can change the dimension using  reshape function  var   np array   1 2 3 4 5 6    1 2 3 4 5 6    reshape 3 4   var ndim  display 2  var shape  display 3  4

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import numpy as np     gt  gt  gt  np shape a   2 2    Also works if the input is not a numpy array but a list of lists   gt  gt  gt  a     1 2   1 2    gt  gt  gt  np shape a   2 2    Or a tuple of tuples   gt  gt  gt  a     1 2   1 2    gt  gt  gt  np shape a   2 2

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It is  shape      ndarray shape   Tuple of array dimensions    Thus    gt  gt  gt  a shape  2  2

[python] Numpy array dimensions

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