pandas 1_4 Flashcards
How do you write a multi-line string in Python?
””” wrap it in three quotes “””
(Python) How would you refer to the first element in a list named my_list?
my_list[0]
(Python) How would you refer to the last element in a list named my_list?
my_list[-1]
(Python) How would you refer to the first two elements in a list named my_list?
my_list[0:2]
(Python) What is a dict surrounded by?
curly brackets
(Python) How would you access 1 in my_dict = {‘a’: 1, ‘b’: 2}?
my_dict[‘a’]
(Python) How would you change ‘a’ to 0 in my_dict = {‘a’: 1, ‘b’: 2}?
my_dict[‘a’] = 0
(Python) How would you add a new item ‘c’ = 3 in my_dict = {‘a’: 1, ‘b’: 2}?
my_dict[‘c’] = 3
(Python) What does this code do?
for x in my_roster_list:
print(x)<br></br><br></br>
prints the values of my_roster_list<br></br>
(Python) What would type([x*2 for x in [1, 2, 3]) return?
list
(Python) What is [x*2 for x in [1, 2, 3]] called?
list comprehension
(Python) How would you turn mydict = {‘a’: 1, ‘b’: 2} into {‘A’: 2, ‘B’: 4} using a dict comprehension?
{key.upper(): value*2 for key, value in mydict.items()}
(Python) How would you turn mydict = {‘a’: 1, ‘b’: 2} into a list [1, 2] using list comprehensions?
[x for _, x in mydict.items()]
(Pandas) How would you print the first five rows of a DataFrame df?
df.head()
(Pandas) What is the function to load a csv into a DataFrame?
pd.read_csv()
(Pandas) What are the two main data structures Pandas gives you?
DataFrame, Series
(Pandas) What is the type of a single DataFrame column?
Series
(Pandas) What is the method to change the index on a DataFrame?
set_index
(Pandas) What is the default index on a DataFrame?
0, 1, 2, … for however many rows are in your data
(Pandas) What is the method to output a DataFrame to a csv?
to_csv
(Pandas) Why do you need the inplace=True argument to make permanent changes to DataFrames via methods?
because otherwise most methods only return a copy of the DataFrame and leave the original untouched
(Pandas) How would you add a column named ‘pts_per_td’ that always equaled 6 to a DataFrame named df?
df[‘pts_per_td’] = 6
(Pandas) What is the name of the method that lets you use functions like upper and replace on your string columns?
str
(Pandas) How do you write ‘or’ when creating boolean columns in Pandas?
|
(Pandas) How do you write ‘and’ when creating boolean columns in Pandas?
&
(Pandas) How do you negate a boolean column in Pandas?
~
(Pandas) What is the method you use to call a function on every value in a column?
apply
(Pandas) What does apply take as an argument?
a function you want to call on every observation in a column in your DataFrame
(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?
axis=1
(Pandas) What keyword argument would you pass the rename function to rename a column ‘old’ to ‘new’?
columns={‘old’: ‘new’}<br></br>
(Pandas) What are missing values in Pandas?
np.nan
(Pandas) What is the DataFrame/Series method that returns True if a value is missing, False if not?
isnull()
(Pandas) What is the DataFrame/Series method that returns True if a value is NOT missing, False if not?
notnull()
(Pandas) What is the method to replace np.nan with values of your choice?
filla()
(Pandas) What method lets you convert between column types?
astype()
(Pandas) What attribute lets you view the types of all your columns in a DataFrame?
dtypes
(Pandas) What does mean(axis=1) calculate the average over?
rows
(Pandas) What is the function to test whether any value of a boolean column is True?
any
(Pandas) What is the function to test whether all values of a boolean column are True?
all
(Pandas) How would you get the frequency of values for df[‘pos’] in Pandas?
df[‘pos’].value_counts()
(Pandas) Given some list of index values, how would you make a DataFrame of only those values?
pass them to loc
(Pandas) What is the second (optional) argument to loc?
column(s) you want to include
(Pandas) When you pass a (similarly index) boolean column to loc, what will it return?
only the rows where the boolean column is True
(Pandas) What does boolean indexing require re: the index of your DataFrame and the boolean column you’re working with?
that they have the same index
(Pandas) How would you filter to only the instances where pos == ‘RB’ in a DataFrame df using loc?
df.loc[df[‘pos’] == ‘RB’]
(Pandas) What is the DataFrame method to drop duplicates?
drop_duplicates
(Pandas) What is the function to return a boolean column indicating whether a row is a duplicate?
duplicated
(Pandas) How would you drop duplicates ONLY among certain columns?
pass the column(s) to drop_duplicates
(Pandas) How would you identify duplicates ONLY among certain columns?
pass the column(s) to duplicated
(Pandas) How do you get drop_duplicates/duplicated to drop/flag ALL duplicate observations (vs all but one duplicate observation)?
by passing keep=False
(Pandas) In a DataFrame df, how would you change column x to 0, ONLY when pos is RB?
df.loc[df[‘pos’] == ‘RB’, ‘x’] = 0
(Pandas) How would you filter to only the instances where pos == ‘RB’ in a DataFrame df using query?
df.query(“pos == ‘RB’”)
