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Today let us look at the basic operations associated with the numpy aarays.
In this article np denotes numpy package.
To create a numpy array
To create a new numpy array or convert a Python list to numpy array format,
the function np.array() is used. It takes a list of elements as parameter. The main advantage
of these numpy arrays are there are built-in looping structure for these
containers. To iterate through the container one need not use a
for-loop. The Python lists take more memory space than the numpy
arrays. Look at the example below.
Array of zeros
To create an array containing only zeros this package provides a function
called np.zeros(). The syntax is
np.zeros ( dim, dtype, order). The parameters are
- dim - dimension in which the array of zeros should be.
- dtype - data type of the values. By default the values are of float type.
- order - It can take up any one of the two-values : 'C'/'F'. Here C denotes store the array in row major order as in C-programming. F denotes store the array in column major order as in FORTRAN.
Look at the example below.
Create array in specified interval:
To create an array of numbers from 'm' to 'n', there is a function
np.arange(). The syntax is
np.arange ( start, stop, step, dtype). The parameters can be thought of as follows:
- start - The value at which to start. By default it is '0'.
- stop - The value at which the interval should end.
- step - The incrementation value. By default it is 1.
- dtype - Datatype of the array to be returned.
Look at the examples below
Identity matrix in Python
To form an identity matrix, numpy provides the funtion
np.eye(). This returns an array containing '1' in the diagonal and
remaining places filled with '0'. The syntax is
np.eye ( R, C, K, dtype). The parameters can be explained as follows:
- R - Number of rows.
- C - Number of columns. It is optional parameter. By default Rows=Columns.
- k - It takes any integer, 1 indicates that the the diagonal above the main diagonal should contain '1'. A value of '-1', indicates that the diagonal below the main diagonal should contain '1'.
- dtype - The data type of the array returned. By default the array values will be of float type.
Look at the example below.
The output for the above coding snippet is
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