Data Science Interview Questions and Answers Set 9

81. What are the possible ways to load an array from a text data file in Python? How can the efficiency of the code to load data file be improved?

numpy.loadtxt ()

82. Which is the standard data missing marker used in Pandas?

NaN

83. Which Python library would you prefer to use for Data Munging?

Pandas

84. Write the code to sort an array in NumPy by the nth column?

Using argsort () function this can be achieved. If there is an array X and you would like to sort the nth column then code for this will be x[x [: n-1].argsort ()]

85. Which python library is built on top of matplotlib and Pandas to ease data plotting?

Seaborn

86. Which plot will you use to access the uncertainty of a statistic?

Bootstrap

87. What is pylab?

A package that combines NumPy, SciPy and Matplotlib into a single namespace.

88. Which python library is used for Machine Learning?

SciKit-Learn

89. How can you copy objects in Python?

a. The functions used to copy objects in Python are-

b. Copy.copy () for shallow copy

c. Copy.deepcopy () for deep copy

d. However, it is not possible to copy all objects in Python using these functions. For instance, dictionaries have a separate copy method whereas sequences in Python have to be copied by ‘Slicing’.

90. What is the difference between tuples and lists in Python?

Tuples can be used as keys for dictionaries i.e. they can be hashed. Lists are mutable whereas tuples are immutable – they cannot be changed. Tuples should be used when the order of elements in a sequence matters. For example, set of actions that need to be executed in sequence, geographic locations or list of points on a specific route.