Python Functions, Data Structures, and Pandas Data Analysis

A generator function uses yield to yield a potentially infinite sequence of values rather than using return once.

True

s = "orange is the new blue"; s.replace("orange", "blue")

"blue is the new blue"

Any function in Python with no return value is actually returning what?

None

L = [2, 3, 5, 7, 11]; L[0:3]

[2, 3, 5]

s = "orange is the new blue"; s.partition(" ")

("orange", " ", "is the new blue")

Compared to lists, the main distinguishing feature of tuples is that they are what?

immutable

In Python every statement must end with a semicolon (;).

False

Strings in Python are created with single or double quotes.

True

a = [1, 2, 3]; b = [5, 7, 9]; a == b

False

result = (4 < 1); result

False

Python arithmetic has limited precision.

False

What statement is used for testing truth in and third-party modules?

import

Loops in Python are a way to repeatedly execute some code statement.

True

System refers to what?

the documentation of the program

numbers = ["one", "two", "three"]; numbers[0] = "four"; numbers

["four", "two", "three"]

L = [0, 1, 2, 7, 11]; L[-1]

11

To check if x is between 15 and 30 in Python, use what expression?

x > 15 and x < 30

In Python, indented code blocks are always preceded by a colon on the previous line.

True

Which one of the following is a generator expression?

(val for val in line)

def add(x, y): z = x + y; return z. How many arguments does add take?

2

L = [2, 5, 1, 0, 3, 4]; L.sort(); L

[0, 1, 2, 3, 4, 5]

a = [1, 2, 3]; b = [1, 2, 3]; a == b

True

if x is 15 < x < 30, then what condition should be used?

x > 15 and x < 30

The Index object follows many conventions used by Python built-in set data structure.

True

indA = pd.Index([1, 3, 5, 7, 9]); indB = pd.Index([2, 3, 5, 7, 11]); indA & indB / intersection

Int64Index([3, 5, 7], dtype="int64")

indA = pd.Index([1, 3, 5, 7, 9]); indB = pd.Index([2, 3, 5, 7, 11]); indA | indB / union

Int64Index([1, 2, 3, 5, 7, 9, 11], dtype="int64")

A Pandas Series is a one-dimensional array of indexed data.

True

A DataFrame is an analog of a two-dimensional array with flexible row indices and flexible column names.

True

Unlike a dictionary, the Series supports array-style operations such as slicing.

True

The index of a Series object should be an integer.

False

Like a dictionary, the Series object provides a mapping from a collection of keys to a collection of values.

True

For data = pd.Series([0.25, 0.5, 0.75, 1.0], index=["a", "b", "c", "d"]), data["a"]

0.25

For data = pd.Series([0.25, 0.5, 0.75, 1.0], index=["a", "b", "c", "d"]), data[1]

0.50

For data = pd.Series(["a", "b", "c"], index=[1, 3, 5]), data[1]

"a"

For data = pd.Series(["a", "b", "c"], index=[1, 3, 5]), data.iloc[1]

"b"

To get states with more than 20 million inhabitants from a DataFrame with pop column, use what?

data["pop"] > 20000000

What are the two special sentinels that can indicate a missing value?

None and NaN

Which Pandas function returns a copy of the data with missing values filled or imputed?

fillna()

Which Pandas function returns a filtered version of the data by dropping missing values?

dropna()

What function can fill each NA value using the previous value in the DataFrame?

data.fillna(method="ffill")

To fill NA entries in a DataFrame data with a single value, such as zero, use what?

data.fillna(0)

Real-world data is rarely clean and homogeneous.

True

What method converts a multiply indexed Series into a conventionally indexed DataFrame?

unstack()

A multi-indexed Series can be converted to a DataFrame.

True

Pandas allows MultiIndex for columns.

True

A MultiIndex can be used to represent data of more than two dimensions in a Series.

True

A multi-index can represent two-dimensional data within a one-dimensional Series.

True

Concatenating two DataFrames can result in duplicate index values.

True

Pandas includes functions and methods that make combining and joining data from multiple sources fast and straightforward.

True

When concatenating two DataFrames, to restrict the result to common columns, use which option?

join="inner"

ser1 = pd.Series(["A", "B", "C"], index=[1, 2, 3]); ser2 = pd.Series(["D", "E", "F"], index=[1, 2, 3]); pd.concat([ser1, ser2])

1 A; 2 B; 3 C; 1 D; 2 E; 3 F

Pandas only supports inner joins.

False

One essential feature of Pandas is high-performance, in-memory join and merge operations.

True

By default, pd.merge() uses common columns across the DataFrames to join.

True

By default, pd.merge() discards the index.

True

Using Pandas, we can manipulate data using relational algebra like relational databases.

True

The pd.merge() function implements one-to-one, many-to-one, and many-to-many joins.

True

A handy Pandas function to calculate descriptive statistics for all columns in a DataFrame is what?

describe()

To aggregate data in Pandas, use what function?

groupby

An essential piece of analysis of large data is efficient summarization by computing aggregations like sum(), mean(), median(), min(), and max().

True

The three steps in a groupby operation are what?

split, apply, combine

It is possible to define custom aggregations in Pandas.

True

To convert a column of string values to multiple columns of numerical values, use which method?

get_dummies() method

Slicing is not allowed in Pandas vectorized string operations.

False

Regular expressions are supported in Pandas vectorized string operations.

True

One advantage of Pandas vectorized strings compared to built-in string methods is what?

graciously handling missing values

Nearly all Python built-in string methods are mirrored by a Pandas vectorized string method.

True

Time deltas reference what?

an exact length of time

To compute aggregate values of time Series over time, use which function?

rolling()

Time stamps reference what?

particular moments in time

The difference between time intervals and periods is what?

Periods usually reference a special case of time intervals in which each interval is of uniform length and does not overlap.

The difference between shift() and tshift() is what?

shift() shifts the data, while tshift() shifts the index

The difference between two Timestamp values is what type?

Timedelta

To create a Timestamp object from the string "May 18 2019", use what?

pd.to_datetime("May 18 2019")

When resampling a time series, the primary difference between resample() and asfreq() is what?

resample() is fundamentally a data aggregation, while asfreq() is fundamentally a data selection

One of the most common problems with REST is what?

overfetching data from the server

Which attribute extracts the response content as a string?

text

JSON encodes complex data by combining what?

lists, dictionaries, strings, and numbers

When a request is sent, whether it was successful is inside which property?

status_code

To convert a Python object to a JSON string, use what?

json.dumps(object)

REST API allows sophisticated queries against the data in the server.

False

Which status code indicates the request was successful and data was returned?

200

Which status code indicates the resource was not found?

404

Which requests function obtains data from a server?

GET

API stands for what?

Application Programming Interface

GraphQL allows for writing a data schema that defines how a client can access the data.

True

Which HTTP method is used to retrieve a specified resource from the Web?

GET

XQUERY and XPATH are incompatible.

False

XQuery is built on XPath expressions.

True

The structure of an XML document is specified with nested attributes.

False

XML stands for what?

Extensible Markup Language

In an XML document, the top-level element is called what?

root

XQuery for XML is like SQL for databases.

True

The code "for $x in doc("books.xml")/bookstore/book where $x/price>30 order by $x/title return $x/title" is an example of what?

an XQUERY query

XML organizes data in what kind of structure?

hierarchical tree-like structure

Which is not designed to process XML documents: XQUERY, ElementTree, SQL, or XPATH?

SQL

HTML tag classes and ids are used for what?

used by CSS to determine which HTML elements to apply certain styles to

When two tags are nested within the same parent tag, they are an example of what relationship?

sibling

Which Python package is used to parse an HTML document?

BeautifulSoup

HTML tags can be nested within other tags.

True