Operating Systems Introduction to NLP Worksheet

Learning PythonFrancisco Iacobelli
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Before you begin
• Download the latest python (3.x). As a suggestion, download Anaconda at https://www.anaconda.
com/. Anaconda installs the latest python version and I recommend you develop with Visual Studio Code
or Spyder. PyCharm is also ok.
• Teach yourself python. You can start by checking this youtube playlist with python for jave programmers.
• Learn how to interact with python from the command line, not from your IDE.This link contains the answer
• Learn how to read parameters from the command line in python. This may help
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TASK
• Create a program that is invoked with a list of integers from the command line. The program should output
the integer that is repeated the most times. If there is a tie, chose any number among those that tie. The
program should be called most_times.py and should be run from the command line like so:
python most_times.py n1 n2 n3 …
where n1 n2… are integers. For example:
python most_times.py 12 1 3 12 5
should output 12 because it is the number that occurs the most times.
• Create a program that reads a filename from the command line and prints the number of unique words, total
number of words (not unique), characters (including spaces) and lines in that file. It must be called wc.py
and must be run like so:
python wc.py filename
where filename is the actual name of the file to read.
As an example, download this sample file: heaalthyeating.txt’.
Then, when your program is run with this file (python wc.py healthyeating.txt), the output of
the program should be in the ballpark of lines:42, unique:429, words:819, chars:4878.
The numbers may vary a bit, but not a lot.
• Modify your program to print the most common and least common word. You must use dictionaries for this.
Using the healthyeating.txt file, python wc.py healthyeating.txt will print:
lines:42, unique:429, words:819, chars:4878
Most frequent word:and (33 times), Less frequent word:People (1 times).
Again, your output may be different than mine if you treat words differently (e.g. you turn all words to
lowercase or something like that).
• Create a file named basic_stats.py that has the following functions:
– avg: takes a list of numbers as a parameter and returns the average.
– l_sqr: takes a list of numbers as a parameter and returns a list with the corresponding values squared.
– var: takes a list of numbers X and computes
∑x∈X (x − µ)2
n
where µ is the average of the numbers in X and n is the number of elements of X.
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*Note: functions must return values, not print them.
To test your file, you may type the following on a python shell:
from basic_stats import *
print(avg([23,32,43,54])==38.0)
print(sum(l_sqr([23,32,43,54]))==6318)
print(var([23,32,43,54])==135.5)
And, when you run it, you should see three True outputs.
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CRITERIA
• The only library you are allowed to use is sys.
• If your work is submitted as specified (check the next section): 30pts.
• If the programs do not have runtime errors running the tests: 20pts.
• each program running correctly is 10 points, and:
– basic_stats must not print anything. Functions should be named exactly as specified and should
return values (5pt.)
– If wc uses dictionaries (5pt.)
– You will get an extra point for every function in basic_sats that only consists of a return statement
that performs the correct functionality (i.e one liners).
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SUBMIT
One ZIP (not arj, rar, etc.) file with the three programs (most_times.py,basic_stats.py and wc.py. All
names of programs and functions should be exactly as specified above, including underscores and case.
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