Comp Sci Expert - Python Specific

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Please complete Lab A and B during today’s session.

Lab A and B File Requirements:

Lab A Overview

This lab explores use of lists and logic for analyzing real data provided by Yelp for restaurants near RPI. You will use a

module that will help you with parsing files. We will learn about files very soon, but feel free to look at the code and ask

about what it is doing during the lab.

To get started, please create a folder in your Dropbox for Lab 3 and download the lab03_util.py and yelp.txt files from

the course website into this new folder. The Python file is a module for reading the second (text input) file. First, take a

look at the lab03_util.py file. You can see it has functions for parsing the file, but no code to call these functions. That is

a simple way to think of a module. We can use these files in our code to simplify some tasks.

Checkpoint 1

Let's use the given module to read this file into a list. Create a new file called check1.py in the same folder as the files

from the zip folder and include the following code inside:

import lab03_util

restaurants = lab03_util.read_yelp(‘yelp.txt’)

Use a few print statements to see the contents of the list. As the list is large, let's look at the first element:

print restaurants[0]

We will get:

["Mekas Lounge", 42.74, -73.69, \

‘407 River Street+Troy, NY 12180’,\

‘http://www.yelp.com/biz/mekas-lounge-troy’, \

‘Bars’, \

[5, 2, 4, 4, 3, 4, 5]]

The variable restaurants contains a list. Each element of this list corresponds to a specific restaurant.

From the above example, we see that the first element of the restaurants list is also a list. The information provided for

each restaurant is: name, latitude, longitude, street address, URL, the restaurant category, and a list of scores given by

Yelp users. Yes, the last element here is yet another list!

Your job in the first checkpoint is to print information for a single restaurant by writing a function called print_info().

Below is the result of printing the first two restaurants in the list:

Mekas Lounge (Bars)

407 River Street

Troy, NY 12180

Lab A Lab B

LabA_chk1.py LabB_chk1.py

LabA_chk2.py LabB_chk2.py

LabA_chk3.py LabB_chk3.py

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Average Score: 3.86

Tosca Grille (American (New))

200 Broadway

Troy, NY 12180

Average Score: 2.50

The first line shows the name and the category in parentheses. The second and third lines both come from the address

(note the use of the TAB here). The final line is the average score, obtained by taking the average of the last entry in the

restaurant. How do we split the address into two lines? There is a very useful function called split() that splits a string

into a list based on a given delimiter. For example:

>>> title = "The,Old,Man,and,the,Sea"

>>> title.split( "," ) [

‘The’, ‘Old’, ‘Man’, ‘and’, ‘the’, ‘Sea’]

>>> title = "The!Old!Man!and!the!Sea"

>>> title.split( "!" )

[‘The’, ‘Old’, ‘Man’, ‘and’, ‘the’, ‘Sea’]

To get you started, here is the basic organization for printing just the name of a restaurant.

import lab03_util

def print_info( restaurant ):

print restaurant[0]

####### main code starts here

restaurants = lab03_util.read_yelp( ‘yelp.txt’ )

print_info( restaurants[0] )

To complete Checkpoint 1, show a mentor the code and the output.

Checkpoint 2

Copy check1.py to check2.py and continue to work on check2.py. Modify your code to ask the user for the id of a

restaurant between 1 and 155 (humans don't need to know about list ids starting at 0). Assume the user enters a

number. If the user enters a value outside of the range 1-155, print a warning and do nothing else.

If the user entered a valid index, print the information for the restaurant corresponding to this index (remember that

index 1 corresponds to list index 0). Test your code well to make sure that you only print a restaurant for a valid index.

The second task in this part is to improve on the print function by changing the average score computation. Given the

scores for a list, drop the max and the min, calculating the average of the rest. Note that you do not actually have to

explicitly remove the max, min, just subtract them from the sum.

Given this average of the remaining scores, print one of the following based on the score:

Score Output

0 to 2 This restaurant is rated bad, based on x reviews.

2 up to 3 This restaurant is rated average, based on x reviews

3 up to 4 This restaurant is rated above average, based on x reviews.

4 up to 5 This restaurant is rated very good, based on x reviews.

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Note that x is the real number of reviews for this restaurant that are used in calculating the average. Beware! It does

not make sense to remove max and min if there are less than three reviews for a restaurant. In that case, we should use

the average of all the values (another if statement!).

To complete Checkpoint 2, show a mentor the code and the output. Please check to make sure your code follows the

structure we require: first imports, then functions, then the actual code. Test your code with values 8, 22, 33, 44, and

other valid and invalid values.

Checkpoint 3

Copy check2.py to check3.py and continue to work on check3.py. We will add a final flair in this part to your program

from part 2.

Your program should work exactly as it did in part 2. After printing the restaurant info, ask the user the following:

What would you like to do next? 1. Visit the homepage 2. Show on Google Maps 3. Show directions to this restaurant

Your choice (1-3)? ==> For all of these options, using formatted strings will really simplify your life!

If the user answers 1, then open a browser window using the following command (but use the URL for the business

instead of this address). Remember to import module webbrowser first of course.

webbrowser.open( ‘http://xkcd.com/1319/’ )

If the user answers 2, then open a browser window with Google maps showing the address of the business.

webbrowser.open( ‘http://www.google.com/maps/place/business-address-goes-here’ )

If the user answers 3, then open a browser window with Google maps with the address of the business and Rensselaer.

Here is an example call:

webbrowser.open( ‘http://www.google.com/maps/dir/business-address/rpi-address’ )

For example, to find the location of Rensselaer, you can use the following call:

webbrowser.open( http://www.google.com/maps/place/110 8th Street Troy NY 12180 )

Luckily, Google can handle spaces or even pluses in an address.

If the user answers anything else, your program does nothing.

To complete Checkpoint 3, show a mentor the code and the output.

Note. This lab had a lot of different components. As a result, it can really benefit from structuring your code in an easy

way so that you can quickly modify and improve it. Take the time to show your code to your TAs and mentors, and also

work with them in restructuring it.

This will be crucial in the future when we write (even) longer code. It helps to design functions to do simple and very

focused things only, for example just printing information regarding a specific restaurant at a certain index.

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Lab B Overview

In this lab, you will write a series of short Python programs to manipulate strings, read input from the user, and display

output. Start by making a folder for Lab 4 in your Dropbox where you keep your Computer Science 1 material, then start

working on the following three checkpoints.

Checkpoint 1: Functions and Framing Four-Letter Words

Create a new program, check1.py, and open it in the WingIDE. There are two parts to this checkpoint:

 Write a function called framed() that creates a text frame around a given word. This function should accept a

single string as an argument. Add code to call your function and test it, e.g.

framed( 'CSCI' ) or framed( 'darn' )

 Next, add code to use the raw_input() function to read a four-letter word into a string. Verify that the string

contains exactly four characters, then pass this string to the framed() function you just wrote. The output when

you run your program should look like this:

Enter a four-letter word: CSCI

**********

** CSCI **

**********

When the user enters invalid input, your program should look like this:

Enter a four-letter word: bananas

ERROR: 'bananas' is not a four-letter word.

When you have this working, show it to a mentor. Make sure your function follows the program structure we discussed

and required in the homeworks. Congratulations, you have completed Checkpoint 1.

Checkpoint 2: Framing Other Words

Be sure you save check1.py and make a copy of it called check2.py. You will modify this for Checkpoint 2. Requiring the

user to type a word that is exactly four letters is limiting, so let's expand your program to accept strings of different

lengths. More specifically, allow the user to enter a string containing at least four characters and at most twelve

characters (otherwise, display the error message shown below).

Also, have the user input the character to use for the border. If the user enters multiple characters, use the first

character entered (and display a warning message). Example program runs are shown below:

Enter a word: CSCI

Enter border character: *

**********

** CSCI **

**********

or

Enter a word: fiddlesticks

Enter border character: #

##################

## fiddlesticks ##

##################

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or

Enter a word: huh

ERROR: 'huh' is too short.

or

Enter a word: arghhhhhhhhhhhhhhhhhh

ERROR: 'arghhhhhhhhhhhhhhhhhh' is too long.

or

Enter a word: fiddlesticks

Enter border character: $*#

WARNING: '$*#' is too long, using '$' for border

$$$$$$$$$$$$$$$$$$

$$ fiddlesticks $$

$$$$$$$$$$$$$$$$$$

When you have this working, show it to a mentor. Congratulations, you have completed Checkpoint 2.

Checkpoint 3: Letter Counting

In this last checkpoint, you will write a new program that determines the number of occurrences of a given letter in a

string. To do so, you are only allowed to use the replace() and len() functions.

Example program runs are shown below:

Enter a sentence: the quick brown fox jumped over the lazy dog

Enter character: t

The letter 't' appears in the sentence exactly 2 times

or

Enter a sentence: the quick brown fox jumped over the lazy dog Enter character: x

The letter 'x' appears in the sentence exactly 1 time

or

Enter a sentence: the quick brown fox jumped over the lazy dog Enter character: s

The letter 's' appears in the sentence exactly 0 times

or

Enter a sentence:

the quick brown fox jumped over the lazy dog Enter character: ?

The letter '?' appears in the sentence exactly 0 times

When you have your program fully working, save your code, and then show the result to a mentor. Congratulations, you

have finished Checkpoint 3 and are all done with Lab 4.