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C T 08 Write Python statements to determine whether there exist an employee with id E004 in
series storing names and salary of employees.
in: Membership operator that allows us to check whether a particular value is present in series.
1.5.6 Checking for Missing Values
Many a times, some of the entries might be missing in the data because of value not known or even not applicable. Let
us reconsider the following marks Series where the NaN indicates that the marks of student with roll number 302 is
missing because he didn't appear for the exam:
>>> import pandas as pd
>>> marks = [90, 70, 95, 45, 100, 65, 78, 29, None]
>>> students = pd.Series(marks, index = [101, 102 , 103, 106, 107, 108, 201, 301, 302])
>>> print(students)
output:
101 90.0
102 70.0
103 95.0
106 45.0
107 100.0
108 65.0
201 78.0
301 29.0
302 NaN
dtype: float64
Suppose we wish to determine if any students have been absent for the test by checking for the presence of missing
values in the marksSeries, as demonstrated below:
>>> students.isnull()
output:
101 False
102 False
103 False
106 False
107 False
108 False
201 False
301 False
302 True
dtype: bool
Now, we use above series of boolean indexes to retrieve the sub-series comprising only those values for which the
index corresponds to the value True i.e. students who have missed the exam, as shown below:
>>> boolIndex = students.isnull()
>>> print(students[boolIndex])
output:
302 NaN
dtype: float64
Data Handling using Pandas 15

