pandas 1_4

Question 1

How do you write a multi-line string in Python?

Answer 1

””” wrap it in three quotes “””

Question 2

(Python) How would you refer to the first element in a list named my_list?

Answer 2

my_list[0]

Question 3

(Python) How would you refer to the last element in a list named my_list?

Answer 3

my_list[-1]

Question 4

(Python) How would you refer to the first two elements in a list named my_list?

Answer 4

my_list[0:2]

Question 5

(Python) What is a dict surrounded by?

Answer 5

curly brackets

Question 6

(Python) How would you access 1 in my_dict = {‘a’: 1, ‘b’: 2}?

Answer 6

my_dict[‘a’]

Question 7

(Python) How would you change ‘a’ to 0 in my_dict = {‘a’: 1, ‘b’: 2}?

Answer 7

my_dict[‘a’] = 0

Question 8

(Python) How would you add a new item ‘c’ = 3 in my_dict = {‘a’: 1, ‘b’: 2}?

Answer 8

my_dict[‘c’] = 3

Question 9

(Python) What does this code do?
for x in my_roster_list:
print(x)<br></br><br></br>

Answer 9

prints the values of my_roster_list<br></br>

Question 10

(Python) What would type([x*2 for x in [1, 2, 3]) return?

Answer 10

list

Question 11

(Python) What is [x*2 for x in [1, 2, 3]] called?

Answer 11

list comprehension

Question 12

(Python) How would you turn mydict = {‘a’: 1, ‘b’: 2} into {‘A’: 2, ‘B’: 4} using a dict comprehension?

Answer 12

{key.upper(): value*2 for key, value in mydict.items()}

Question 13

(Python) How would you turn mydict = {‘a’: 1, ‘b’: 2} into a list [1, 2] using list comprehensions?

Answer 13

[x for _, x in mydict.items()]

Question 14

(Pandas) How would you print the first five rows of a DataFrame df?

Answer 14

df.head()

Question 15

(Pandas) What is the function to load a csv into a DataFrame?

Answer 15

pd.read_csv()

Question 16

(Pandas) What are the two main data structures Pandas gives you?

Answer 16

DataFrame, Series

Question 17

(Pandas) What is the type of a single DataFrame column?

Answer 17

Series

Question 18

(Pandas) What is the method to change the index on a DataFrame?

Answer 18

set_index

Question 19

(Pandas) What is the default index on a DataFrame?

Answer 19

0, 1, 2, … for however many rows are in your data

Question 20

(Pandas) What is the method to output a DataFrame to a csv?

Answer 20

to_csv

Question 21

(Pandas) Why do you need the inplace=True argument to make permanent changes to DataFrames via methods?

Answer 21

because otherwise most methods only return a copy of the DataFrame and leave the original untouched

Question 22

(Pandas) How would you add a column named ‘pts_per_td’ that always equaled 6 to a DataFrame named df?

Answer 22

df[‘pts_per_td’] = 6

Question 23

(Pandas) What is the name of the method that lets you use functions like upper and replace on your string columns?

Answer 23

str

Question 24

(Pandas) How do you write ‘or’ when creating boolean columns in Pandas?

Answer 24

|

Question 25

(Pandas) How do you write 'and' when creating boolean columns in Pandas?

Answer 25

&

Question 26

(Pandas) How do you negate a boolean column in Pandas?

Answer 26

~

Question 27

(Pandas) What is the method you use to call a function on every value in a column?

Answer 27

apply

Question 28

(Pandas) What does apply take as an argument?

Answer 28

a function you want to call on every observation in a column in your DataFrame

Question 29

(Pandas) When dropping a column in a DataFrame using the drop method, what argument do you have to pass so that it drops a column instead of a row?

Answer 29

axis=1

Question 30

(Pandas) What keyword argument would you pass the rename function to rename a column 'old' to 'new'?

Answer 30

columns={'old': 'new'}

Question 31

(Pandas) What are missing values in Pandas?

Answer 31

np.nan

Question 32

(Pandas) What is the DataFrame/Series method that returns True if a value is missing, False if not?

Answer 32

isnull()

Question 33

(Pandas) What is the DataFrame/Series method that returns True if a value is NOT missing, False if not?

Answer 33

notnull()

Question 34

(Pandas) What is the method to replace np.nan with values of your choice?

Answer 34

filla()

Question 35

(Pandas) What method lets you convert between column types?

Answer 35

astype()

Question 36

(Pandas) What attribute lets you view the types of all your columns in a DataFrame?

Answer 36

dtypes

Question 37

(Pandas) What does mean(axis=1) calculate the average over?

Answer 37

rows

Question 38

(Pandas) What is the function to test whether any value of a boolean column is True?

Answer 38

any

Question 39

(Pandas) What is the function to test whether all values of a boolean column are True?

Answer 39

all

Question 40

(Pandas) How would you get the frequency of values for df['pos'] in Pandas?

Answer 40

df['pos'].value_counts()

Question 41

(Pandas) Given some list of index values, how would you make a DataFrame of only those values?

Answer 41

pass them to loc

Question 42

(Pandas) What is the second (optional) argument to loc?

Answer 42

column(s) you want to include

Question 43

(Pandas) When you pass a (similarly index) boolean column to loc, what will it return?

Answer 43

only the rows where the boolean column is True

Question 44

(Pandas) What does boolean indexing require re: the index of your DataFrame and the boolean column you're working with?

Answer 44

that they have the same index

Question 45

(Pandas) How would you filter to only the instances where pos == 'RB' in a DataFrame df using loc?

Answer 45

df.loc[df['pos'] == 'RB']

Question 46

(Pandas) What is the DataFrame method to drop duplicates?

Answer 46

drop_duplicates

Question 47

(Pandas) What is the function to return a boolean column indicating whether a row is a duplicate?

Answer 47

duplicated

Question 48

(Pandas) How would you drop duplicates ONLY among certain columns?

Answer 48

pass the column(s) to drop_duplicates

Question 49

(Pandas) How would you identify duplicates ONLY among certain columns?

Answer 49

pass the column(s) to duplicated

Question 50

(Pandas) How do you get drop_duplicates/duplicated to drop/flag ALL duplicate observations (vs all but one duplicate observation)?

Answer 50

by passing keep=False

Question 51

(Pandas) In a DataFrame df, how would you change column x to 0, ONLY when pos is RB?  

Answer 51

df.loc[df['pos'] == 'RB', 'x'] = 0

Question 52

(Pandas) How would you filter to only the instances where pos == 'RB' in a DataFrame df using query?

Answer 52

df.query("pos == 'RB'")