14. Advanced Python Modules Flashcards
How do you import counter()
from collections import Counter
What does Counter() do?
Counter is a dict subclass which helps count hashable objects. Inside of it elements are stored as dictionary keys and the counts of the objects are stored as the value.
lst = [1,2,2,2,2,3,3,3,1,2,1,12,3,2,32,1,21,1,223,1]
- *Counter(lst)**
- *Counter({1: 6, 2: 6, 3: 4, 12: 1, 21: 1, 32: 1, 223: 1})**
How do you import defaultdict()?
from collections import defaultdict
What does defaultdict() do?
defaultdict is a dictionary-like object which provides all methods provided by a dictionary but takes a first argument (default_factory) as a default data type for the dictionary. Using defaultdict is faster than doing the same using dict.set_default method.
Does Defaultdict() ever create an error?
no
A defaultdict will never raise a KeyError. Any key that does not exist gets the value returned by the default factory.
What does defaultdict() look like?
d is empty but no error is created
d = defaultdict(object)
d[‘one’]
How do you import a namedtuple?
from collections import namedtuple
What does a namedtuple look like?
Dog = namedtuple(‘Dog’, [‘age’,’breed’,’name’])
sam = Dog(age=2,breed=’Lab’,name=’Sammy’)
frank = Dog(age=2,breed=’Shepard’,name=”Frankie”)
so:
sam
Dog(age=2, breed=’Lab’, name=’Sammy’)
sam.age
2
How do you create a file?
f = open(‘practice.txt’, ‘w+’)
f. write(‘test’)
f. close()
How do you get the current directory?
- *import os
os. getcwd()**
So, for example:
‘C:\Users\Marcial\Pierian-Data-Courses\Complete-Python-3-Bootcamp\12-Advanced Python Modules’
How do you list files in a directory?
import os
In your current directory
os.listdir()
How do you list files in a specific directory?
os.listdir(“C:\Users”)
How do you move a file?
import shutil
shutil.move(‘practice.txt’,’C:\Users\Marcial’)
How do you list files in a directory?
In your current directory
os.listdir()
How do you list files in a specific directory
os.listdir(“C:\Users”)
How do you delete a file?
import send2trash
send2trash.send2trash(‘practice.txt’)
How do you walk through a directory?
for folder , sub_folders , files in os.walk(“Example_Top_Level”):
For regular expressions, what does \d represent?
A digit
For regular expressions, what does \w represent?
Alphanumeric
For regular expressions, what does \s represent?
White space
For regular expressions, what does \D represent?
a non digit
For regular expressions, what does \W represent?
Non-alphanumeric
For regular expressions, what does \S represent?
non-whitespace
For regular expressions, what is a quantifier?
+ {n} * ?
where n is some number.
Now that we know the special character designations, we can use them along with quantifiers to define how many we expect.
Character Description Example Pattern Code Exammple Match
+ Occurs one or more times Version \w-\w+ Version A-b1_1
{3} Occurs exactly 3 times \D{3} abc
{2,4} Occurs 2 to 4 times \d{2,4} 123
{3,} Occurs 3 or more \w{3,} anycharacters
* Occurs zero or more times A*B*C* AAACC
? Once or none
For regular expressions, what does + represent?
Occurs one or more times
For regular expressions, what does * represent?
Occurs zero or more times.
For regular expressions, what does ? represent?
Once or none.
For regular expressions, what does {3} represent?
Occurs exactly 3 times.
For regular expressions, what does {2,4} represent?
Ocucurs 2 to 4 times.
For regular expressions, what does {3,} represent?
Occurs 3 or more times.
For regular expressions, what does | represent?
Or
re. search(r”man|woman”,”This man was here.”)
re. search(r”man|woman”,”This woman was here.”)
For regular expressions, what does a . represent?
A wildcard
What module is used to time your code?
timeit
How do you import timeit?
import timeit
What are the three pieces needed to use timeit()
* the setup of the function to be timed.
It needs to be in a string format:
setup = ‘’’
def func_one(n):
return [str(num) for num in range(n)]
‘’’
* The statement name.
Also needs to be in a string format:
stmt = ‘func_one(100)’
* The number of times to test the function
number=100000
The end product:
timeit.timeit(stmt, setup, number=100000)
What is the Jupyter ‘magic’ method to time your code.
%%timeit
func_one(100)
What module needs to be imported to zip files?
import zipfile
What is the first step to zip a file?
Create a zip file.
comp_file = zipfile.ZipFile(‘comp_file.zip’, ‘w’)
What is the second step to zip a file?
Move the file into the already created zip file, and zip the file while doing this.
comp_file.write(“new_file.txt”,compress_type=zipfile.ZIP_DEFLATED)
What is the final step when zipping a file?
close the zip file
comp_file.close()
What module would you use to archive a folder?
shutil
How do you zip an entire folder?
import shutil
Save to a variable the file path of directory to be zip
directory_to_zip=’C:\Users\Marcial\Pierian-Data-Courses\Complete-Python-3-Bootcamp\12-Advanced Python Modules’
Save name of archieve to a variable
output_filename = ‘example’
#use the function: shutil.make_archive()
Note this won’t run as is because the variable are undefined
shutil.make_archive(output filename, ‘zip’, directory_to_zip)
How do you un-zip a zip archive?
shutil.unpack_archive(output_filename, dir_for_extract_result, ‘zip’)
How do you import the datetime module?
import datetime
How do I use the datetime module?
import datetime
t = datetime.time(4, 20, 1)
Let’s show the different components
print(t)
print(‘hour :’, t.hour)
print(‘minute:’, t.minute)
print(‘second:’, t.second)
print(‘microsecond:’, t.microsecond)
print(‘tzinfo:’, t.tzinfo)
So:
04:20:01
hour : 4
minute: 20
second: 1
microsecond: 0
tzinfo: None
Note: A time instance only holds values of time, and not a date associated with the time.
How do you check the minimum, maximum, and resolution of the time?
print(‘Earliest :’, datetime.time.min)
print(‘Latest :’, datetime.time.max)
print(‘Resolution:’, datetime.time.resolution)
So:
Earliest : 00:00:00
Latest : 23:59:59.999999
Resolution: 0:00:00.000001
The min and max class attributes reflect the valid range of times in a single day.
How do you use datetime to find the current day?
today = datetime.date.today()
print(today)
print(‘ctime:’, today.ctime())
print(‘tuple:’, today.timetuple())
print(‘ordinal:’, today.toordinal())
print(‘Year :’, today.year)
print(‘Month:’, today.month)
print(‘Day :’, today.day)
So:
2020-06-10
ctime: Wed Jun 10 00:00:00 2020
tuple: time.struct_time(tm_year=2020, tm_mon=6, tm_mday=10, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=2, tm_yday=162, tm_isdst=-1)
ordinal: 737586
Year : 2020
Month: 6
Day : 10
How do you use replace() to create a date instance?
d1 = datetime.date(2015, 3, 11)
print(‘d1:’, d1)
d2 = d1.replace(year=1990)
print(‘d2:’, d2)
So:
d1: 2015-03-11
d2: 1990-03-11
A simple use of arithmetic with datetime?
d1 = datetime.date(2015, 3, 11) d2 = datetime.date(1990, 3, 11)
d1 - d2
So:
datetime.timedelta(9131)
This gives us the difference in days between the two dates. You can use the timedelta method to specify various units of times (days, minutes, hours, etc.)
How do you import the math module?
import math
How do you find help with the math module?
help(math)
What are the three ways to round a number?
value = 4.35
- *math.floor**(value) #4
- *math.ceil**(value) #5
- *round**(value) #4
Is round() part of the math module?
No
What are the math constants in the math module?
math. pi #3.141592653589793
math. e #2.718281828459045
math. tau #6.283185307179586
math. inf #inf
math. nan #nan
What does the log() function look like?
Log Base e
math.log(math.e) # 1
What is the default base of log()?
e
math. log(10) # 2.302585092994046
math. e ** 2.302585092994046 # 10.000000000000002
How do you use a custom base with log()?
math. log(x,base)
* math.log(100,10) # 2.0*
How do you find the sine of a number using the math module?
Radians
math.sin(10)
By default does the math module use degrees or radians?
radians
How do you convert to degrees using the math module?
math.degrees(pi/2) # 90.0
How do you convert to radians using the math module?
math.radians(180) # 3.141592653589793
With the Random module, what does the seed do?
We can even set a seed to produce the same random set every time.
How do you set the seed of the random function?
The value 101 is completely arbitrary, you can pass in any number you want
random.seed(101)
Using the random module, how do you “sample with replacement”?
Take a sample size, allowing picking elements more than once. Imagine a bag of numbered lottery balls, you reach in to grab a random lotto ball, then after marking down the number, you place it back in the bag, then continue picking another one.
random.choices(population=mylist,k=10)
[15, 14, 17, 8, 17, 2, 19, 17, 6, 1]
Using the random module, how do you “sample without replacement”?
[17, 19, 11, 14, 1, 3, 4, 10, 5, 15]
Once an item has been randomly picked, it can’t be picked again. Imagine a bag of numbered lottery balls, you reach in to grab a random lotto ball, then after marking down the number, you leave it out of the bag, then continue picking another one.
random.sample(population=mylist,k=10)
Using the random module, how do you shuffle a list?
Don’t assign this to anything!
random.shuffle(mylist)
Using the random module, how do you create a random distribution?
Continuous, random picks a value between a and b, each value has equal change of being picked.
random.uniform(a=0,b=100)
How do you import the Python debugger?
import pdb
What is the most important Python debugger function?
Set a trace using Python Debugger
pdb.set_trace()
How do you import regular expressions into Python?
import re
Using regular expressions how do you find the word ‘phone’ in a sentence?
text = “The person’s phone number is 408-555-1234. Call soon!”
import re
pattern = ‘phone’
re.search(pattern, text)
Using regular expressions, how do you display just the span of what you are searching for?
match.span() # (13, 18)
Using regular expressions, how do you display just the start of what you are searching for?
match.start() # 13
Using regular expressions, how do you display just the end of what you are searching for?
match.end() # 18
Using regular expressions, if there is more than one result for what is being searched for, how do you return all of the results?
matches = re.findall(“phone”, text)
returns a list of found items.
Using regular expressions, how do iterate all the results?
for match in re.finditer(“phone”,text):
print(match.span())
(3, 8) # (18, 23)
