Series creation from lists and dicts in Data Analysis Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a pandas Series?

A pandas Series is like a single column of data with labels (called an index). It can hold numbers, words, or other data types.

beginner

How do you create a Series from a list in pandas?

Use pd.Series(your_list). The list values become the data, and pandas automatically creates index numbers starting at 0.

beginner

How does pandas create a Series from a dictionary?

When you pass a dictionary to pd.Series(), the dictionary keys become the index labels, and the values become the data.

intermediate

Can you assign custom index labels when creating a Series from a list?

Yes! Use the index parameter like pd.Series(data, index=[labels]) to set your own labels instead of default numbers.

intermediate

What happens if you create a Series from a dict but specify an index with labels not in the dict?

Pandas will create entries for those labels with NaN (missing) values because the dict has no data for them.

What does pd.Series([10, 20, 30]) produce?

A A Series with values 10, 20, 30 and index 0, 1, 2

B A Series with index 10, 20, 30 and values 0, 1, 2

C A DataFrame with 3 columns

D An error because list is not allowed

Passing a list creates a Series with the list values as data and default numeric index starting at 0.

If you create a Series from a dict {'a': 1, 'b': 2}, what will be the index?

A ['a', 'b']

B ['b', 'a']

C [1, 2]

D [0, 1]

The dict keys become the Series index labels.

How can you create a Series from a list with custom labels 'x', 'y', 'z'?

A pd.Series(data, labels=['x', 'y', 'z'])

B pd.Series(data).labels(['x', 'y', 'z'])

C pd.Series(data, index=['x', 'y', 'z'])

D pd.Series(data).index(['x', 'y', 'z'])

Use the index parameter to assign custom labels.

What value does pandas assign if an index label is not found in the dictionary when creating a Series?

A Raises an error

B 0

C Empty string

D NaN

Pandas uses NaN to represent missing data.

Which of these is a valid way to create a Series from a dictionary?

A pd.Series(1, 2, 3)

B pd.Series({'a': 1, 'b': 2})

C pd.Series(['a', 'b'], [1, 2])

D pd.Series('a':1, 'b':2)

Passing a dictionary directly to pd.Series creates a Series with keys as index and values as data.

Explain how to create a pandas Series from a list and how to add custom index labels.

Think about the parameters of pd.Series()

Describe what happens when you create a Series from a dictionary and specify an index with labels not in the dictionary.

Consider how pandas handles missing data