Objective Questions
-------------------
.. A mininum of 8 questions here (along with answers)
1. An array in Python is the same as a Python list
a. True
#. False
Answer: False
2. ``x = array([1, 2, 3], [5, 6, 7])`` is a valid statement
a. True
#. False
Answer: False
3. What will be the output of the following code,
::
x = array([[1, 2, 3], ['a', 2, 'c']])
print x[0][0] + x[0][1] + x[0][2]
a. 6
#. 123
#. a2c
#. Error as array takes only homogeneous elements
Answer: 123
4. What will be the output of the following code,
::
x = [[1, 2, 3], [4.1, 4.2, 4.3], ['6','7',8]]
y = array(x)
print y[-1][-2] + y[-1][-1] + y[-2][0] + y[0][-2]
a. 21.1
#. 12.5
#. 784.12
#. Error as array takes only homogeneous elements
.. 4.2 4.3 2 2
Answer: 784.12
5. What is the output of the following code,
::
x = array([[1, 2, 3], ['a', 2, 'c']])
identity(x.shape)
a. Will create an identity matrix of shape (2, 3).
#. ``identity()`` function takes an integer as argument and a tuple
is passed.
#. Will return, array([[1,0,1],[0,1,0]])
#. Will return, array([[0,1,0],[0,1,0]])
Answer: ``identity()`` function takes an integer as argument and a
tuple is passed.
6. ``ones_like()`` function?
(A) Returns an array of ones with the same shape and type as a
given array.
(B) Return a new array of given shape and type, filled with ones.
Read the statements and answer,
a. Only statement A is correct.
#. Only statement B is correct.
#. Both statement A and B are correct.
#. Both statement A and B are incorrect.
Answer: Only statement A is correct.
7. ``zeros_like()`` function?
(A) Return a new array of given shape and type, filled with zeros.
(B) Returns an array of zeros with the same shape and type as a
given array.
Read the statements and answer,
a. Only statement A is correct.
#. Only statement B is correct.
#. Both statement A and B are correct.
#. Both statement A and B are incorrect.
Answer: Only statement B is correct.
8. What will be output of the following code snippet.
::
x = linspace(1,10,10).reshape(5,2)
print (x[-3]+x[-4]).sum()
a. 10.0
#. 18.0
#. 14.0
#. 16.44
#. Error
Answer: 18
Larger Questions
----------------
.. A minimum of 2 questions here (along with answers)
1. Write a python script to create a 15x15 array of equally spaced 225
elements from 1 to 1000, add 5 to each of the diagonal elements and
find the sum of all odd rows of the array. Say for example the
array,
::
x = array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
will give answer 40 ((1+5) + 2 + 3 + 7 + 8 + (9+5)).
2. For any given array([a1, a2, a3, .. , an]) the Vandermonde matrix
will be [[1, a1, a1**2, .. , a1**(n-1)], [1, a2, a2**2, .. ,
a2**(n-1)], .. , [1, an, an**2, .. ,an**(n-1)]]. Write a python
script to generate the Vandermonde matrix and find the determinant
of the matrix for [2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
16, 17, 18, 19, 20]. [Hint: to find the determinant use the
function ``det()`` from ``linalg`` module.]