Methods of Series

Understanding Series Methods

A Pandas Series comes with built-in methods that let you quickly inspect, summarise, and manipulate your data. These methods save you from writing loops or manual slicing. The textbook introduces three essential methods using a sample Series created from np.arange(10, 20, 1), which holds the integers 10 through 19.

>>> seriesTenTwenty = pd.Series(np.arange(10, 20, 1))
>>> print(seriesTenTwenty)
0    10
1    11
2    12
3    13
4    14
5    15
6    16
7    17
8    18
9    19
dtype: int32

Each method is designed for a specific task — looking at the beginning, counting valid entries, or checking the end.

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head(n) — First Few Members

The head() method returns the first n elements of the Series. If you do not pass any argument, it defaults to showing the first 5 entries. This is extremely useful when you have a large dataset and just want a quick peek at the top rows to confirm the data looks correct.

Example with argument:

>>> seriesTenTwenty.head(2)
0    10
1    11
dtype: int32

Here, only the first two values (10 and 11) are returned.

Example without argument (default behaviour):

>>> seriesTenTwenty.head()
0    10
1    11
2    12
3    13
4    14
dtype: int32

The first five values are displayed.

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count() — Number of Non-NaN Values

The count() method returns the total number of non-NaN (i.e., non-missing) values in the Series. It ignores any NaN entries automatically. In our sample Series, all 10 values are present and valid, so it returns 10.

>>> seriesTenTwenty.count()
10

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tail(n) — Last Few Members

The tail() method works exactly like head(), but from the opposite end — it returns the last n elements. Again, the default is 5 if no argument is given.

Example with argument:

>>> seriesTenTwenty.tail(2)
8    18
9    19
dtype: int32

The last two values (18 and 19) are shown.

Example without argument (default behaviour):

>>> seriesTenTwenty.tail()
5    15
6    16
7    17
8    18
9    19
dtype: int32

The last five values are displayed.

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Quick Reference Table

| Method | Purpose | Default n | Example Output (with n=2) | …