parsing_data/questions.rst
author anand
Sun, 07 Nov 2010 01:18:26 +0530
changeset 390 69f285b3a5ed
parent 238 c507e9c413c6
permissions -rw-r--r--
checklist OK for `accessing pieces arrays`

Objective Questions
-------------------

 1. How do you split the string "Guido;Rossum;Python" to get the words

   Answer: line.split(';')

 2. line.split() and line.split(' ') are same

   a. True
   #. False

   Answer: False

 3. What is the output of the following code::

      line = "Hello;;;World;;"
      sub_strs = line.split()
      print len(sub_strs)

    Answer: 5

 4. What is the output of "      Hello    World    ".strip()

   a. "Hello World"
   #. "Hello     World"
   #. "      Hello World"
   #. "Hello World     "
   
   Answer: "Hello    World"

 5. What does "It is a cold night".strip("It") produce
    Hint: Read the documentation of strip

   a. "is a cold night"
   #. " is a cold nigh" 
   #. "It is a cold nigh"
   #. "is a cold nigh"

   Answer: " is a cold nigh"

 6. What does int("20") produce

   a. "20"
   #. 20.0
   #. 20
   #. Error

   Answer: 20

 7. What does int("20.0") produce

   a. 20
   #. 20.0
   #. Error
   #. "20"

   Answer: Error

 8. What is the value of float(3/2)

   a. 1.0
   #. 1.5
   #. 1
   #. Error

   Answer: 1.0

 9. what doess float("3/2") produce

   a. 1.0
   #. 1.5
   #. 1
   #. Error

   Answer: Error
   
 10. See if there is a function available in pylab to calculate the mean
     Hint: Use tab completion

Larger Questions
================

 1. The file ``pos.txt`` contains two columns of data. The first and second
    columns are the x and y co-ordiantes of a particle in motion, respectively.
    Plot the trajectory of the particle.

   Answer::

     x_values = []
     y_values = []

     for line in open("/home/fossee/pos.txt");
         x_str, y_str = line.split()
         x = int(x_str)
         y = int(y_str)

         x_values.append(x)
         y_values.append(y)

         plot(x, y, 'b.')