DANL chapter 2-9
Which of the following concatenates a sequence of elements of a list into a string separated by a space?
" ".join(seq)
What gets printed? numbers = [1, 2, 3, 4] numbers.extend([5,6,7,8]) print(len(numbers))
8
The expression used to check the value of A is equivalent the value of B in Python is
A == B
What is the following code an example of? if choice == 'a': print('Bad guess') elif choice == 'b': print('Good guess') elif choice == 'c': print('Close, but not correct')
A chained conditional
Which type of chart would be best for displaying a categorical variable?
Bar chart
What chart would be best for showing values over a given area or region?
Choropleth
Chord diagrams are good for displaying the
Connections between items
Scatterplots are good for displaying the
Correlation between two variables
What chart type would be best for showing the distribution of a variable?
Density
Histograms are good for displaying the
Distribution of a variable
What does the while statement do?
Execute a block of commands until the Boolean condition becomes False
Given X="ABCDEFGHIJKLMNOPQRSTUVWXYZ", X[5:19:2] is?
FHJLNPR
Code indentation must be exactly 4 spaces when creating a code block.
False
In a dictionary, you can set multiple values to the same key.
False
The "add" method adds elements to the end of a list.
False
Which type of chart would be best for displaying a variable over time?
Line graph
Dictionaries differ from lists, sets, and tuples because
Lists, sets, and tuples use integers for index positions and dictionaries can use almost any Python type.
To find out where a program is operating, you can use the the following function from the pathlib Path object
Path.cwd()
Donut graphs are good for displaying the
Percentage of values within a variable
What does the "short-circuit rule" refer to?
Python logical expressions resolve to the answer when no more can be gained from evaluating the rest of the expression
Lollipop plots are good for displaying the
Ranking of values within a variable
What chart would be best for showing the flow of a variable between two or more states?
Sankey
A one-dimenstional array-like object in pandas is called a
Series
What is an example of the accumulator pattern?
Starting a variable with the initial value, updating the variable with its own value over and over
Given X="ABCDEFGHIJKLMNOPQRSTUVWXYZ", X[19:6:-2] is?
TRPNLJH
What is wrong with this code? for i in range(1,10,1): print(i)
The print statement needs to be indented
What is wrong with this code? for i in range(10,1,1): print(i)
The range should be range(10,0,-1)
What is wrong with the following code? def averege(numbers): return sum(numbers)/len(numbers)
The return should be indented
What is wrong with this code? for i in range(1,10,1): print(i)
There is nothing wrong with the code
Why would you use the "try" and "except" reserved words?
To safeguard your program from unexpected runtime errors
Indentation is important when using the if statement.
True
MyData32 is a valid variable name.
True
_MyData32 is a valid variable name.
True
Which of the following is a valid Python variable name?
X52_662zeta
Given X=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25], X[25:18:-3] is?
[25, 22]
Given X=[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25], X[6:8:2] is?
[7]
The worksheet that is currently (or most recently) viewed is called the
active sheet
What is the following compares elements of both lists?
cmp(list1, list2)
The "on" option of pd.merge determines the
column names to use as the keys for merging
To bring all the content of a file into a Python program, you would use a Python statement like
contents = fhandle.read()
Casting is
converting from one data type into another
To separate a Series into a set of buckets, you can use the method
cut()
Which of the following methods extracts all of the key-value pairs from a dictionary called d?
d.items()
Which of the following methods extracts all of the values from a dictionary called d?
d.values()
For reading dates in European format (dd-mm-yyyy), you would add the option to read_csv()
dayfirst=True
f = lambda x: x.max() - x.min()
defines a function called f that calculates the range
To calculate the statistics of a pandas DataFrame, you can use the method
describe()
To read data from comma delmited values from a file called "data.dat" into pandas, you would use
df = pd.read_csv("data.dat")
To read data from a data file "data.xlsx" into pandas, you would use
df = pd.read_excel("data.xlsx")
To delete rows 'a' and 'b' from a DataFrame called df, you can use
df.drop(['a','b'])
To delete columns 'a' and 'b' from a DataFrame called df, you can use
df.drop(['a','b'],axis="columns")
To select a row by label 'a' from a DataFrame df, you use
df.loc['a']
To select a column by label 'a' from a DataFrame df, you use
df.loc[:,'a']
To caluclate the averages of a DataFrane df, you use
df.mean()
To sort a dataframe df by its content, you use
df.sort_values()
To sort the "df" dataframe on the primary column key "ID" and second column key "Date", you can use
df.sort_values(by=["ID","Date"])
To find the distribution of values of column 'a' in dataframe df, you use
df["a"].value_counts()
To remove replicated data, you can use the method
drop_duplicates()
The Python object for working with a file is called a
file handle
To set missing values to a set value, you can use the method
fillna()
The statement "something wrong = 5"
generates "SyntaxError: invalid syntax" error
To include functions from a module, you use
import
The convention for bringing pandas into a Python program is
import pandas as pd
To interact with a Web API, you can use
import requests
What is the following gives the total length of the list?
len(list)
What is the following inserts an object at given index in a list?
list.insert(index, obj)
What is the following removes an object from a list?
list.remove(obj)
To perform a calculation on every element of a Series, you can use
map()
Which of the following convert a single character to its character code (as an integer) in Python?
ord(x)
To find out what files and directories are in a directory, you would use
os.listdir()
When you are finished with using a file handle called output in Python, you should call the function
output.close()
The location of a file is known as the
pathname
To stack two DataFrames (df1 and df2), you can use
pd.concat([df1,df2])
To convert a "wide" formatted dataframe "df" to a "long" format on "key", you can use
pd.melt(df,["key"])
To include rows from both DataFrames (df1 and df2), no matter which dataframe the data is in, you use
pd.merge(df1,df2,how="outer")
The operator for division is
plain] /
Which of the following functions convert a string to a set in Python?
set(x)
The statement "something = 1,"
sets the variable 'something' to (1,)
To ignore the last top 20 lines at the end of a file, you would add the option to read_csv()
skip_footer=20
Which of the following convert an integer to an unicode character in Python?
unichr(x)
Which of the following converts a string to all uppercase?
upper()
To write the workbook "wb" to disk as "new.xlsx", you would use
wb.save("new.xlsx")
To get a list of sheets in an Excel workbook called "wb", you would use
wb.sheetnames
To add a value "x" to a dictionary called "words" linked to "a", you would use
words["a"] = "x"
To create a compressed archive of files, you can use the
zipfile library