parsing.md

Extracting information from a file

Rarely you can use the information from a file directly. Most of the time you will need to parse it, that is extracting relevant information.

Parsing means for instance:

• dividing tables into columns
• converting numbers to integers or floats.
• discarding unnecessary lines.

Warming up

Create a text file in a text editor. Write the following line there:

Alice Smith;23;Macroeconomics

Save the file with the name alice.txt.

Then run the following program:

f = open('alice.txt')
print(f)
text = f.read()
print(text)
columns = text.strip().split(';')
print(columns)
name = columns[0]
age = int(columns[1])
studies = columns[2]
print(name)
print(age)
print(studies)

What happens?

Exercises

Exercise 1

What does the following line produce?

"Take That".split('a')

Exercise 2

Create a text file with the contents:

Alice Smith;23;Macroeconomics
Bob Smith;22;Chemistry
Charlie Parker;77;Jazz

Write a program that reads all names and puts them into a list. Print the list.

Exercise 3

Collect the ages into a separate list.

Exercise 4

Collect the occupations into a separate list.

Exercise 5

Leave the strip() command away from the above program. What happens?

The Challenge: Find Your name

Write a program that finds out how often your name occurs in the list of 2014 baby names and print that number.

Extra Challenge:

• Calculate the total number of babies registered in 2014.