PythonOnSHIPs

Tutorial 1: Overview of Programming

Presents the basic concepts of programming for newbies.

File:Python1.pdf

Tutorial 2: Data, Variables and Math operators

An introduction to the python interpreter, variables and types of data they store. Using math functions and python as a calculator.

File:Python2.pdf

Exercises:

• Evaluate the square root of 10.1*10.2 + 15.3*15.4
• What happens when you add two string variables together?
• Create a numpy integer array of values from 0 to 100, incrementing in steps of 2
• Create a numpy floating-point array of 101 elements that range in value from 0.0 to 1.0
• Perform the following operations (in order) on the previous array: trignometric cosine, multiply by 1000.0 and convert it to integer format.
• Find the minimum and maximum value of the resulting array in previous exercise.
• Find the sum total of all elements of the resulting array.
• What is the length of the array 'a' created by the following numpy command: a = np.zeros( int(np.sqrt(np.pi*100)+3.) )?
• What is the data type of the array 'a' in the previous exercise?
• Create an array 'x' of size 20 with floating point values between 1 and 20. Create a second array 'y' of size 20 with floating point values between 1 and 20. These represent the (x,y) coordinate values of 20 objects on a Cartesian grid. Calculate the distance between a point at (2.5,7.8) and all (x,y) pair objects, and store the resulting distance values in a variable 'dist'.
• Create a 2-Dimensional numpy array of size 15 columns X 17 rows filled with zeros. Set the middle column to 10. Set the last five rows to 20.

Tutorial 3: Controlling program flow

Script writing for python and If/Then/Else constructs and loops.

File:Python3.pdf

Exercises:

• For all prime numbers up to 13, calculate and print the square of the prime number.
• Define a list of 5 stars in numpy variables x, y, flux. Where, x, y are the coordinates and flux is the brightness in some units. For the star in the middle of the list (at index position 2) write a script to calculate and print the difference in position and in flux between all stars in the list and that star.
• A star has a position as follows: ra = 15.2345 (degrees), dec = -45.23435 (degrees) in epoch J2000.0 measurements. It has a proper motion of -1.2 "/yr in right ascension and +0.35 "/yr in declination. Write a program to print the right ascension and declination of the object when WISE looks at it in April of 2009?
• Write a script to calculate and print when this object cross the declination line at 0.0?