Transcript 2007Jan-pythonwin-day2

Windows
Python Tutorial
Title
Center for Coastal and
Ocean Mapping
NOAA/UNH Joint
Hydrographic Center
Kurt Schwehr
Jan 2007
Day 2
More python
• Loops and tests
• Plotting
• And more…
Class website:
http://vislab-ccom.unh.edu/~schwehr/Classes
What does
perl look
like?
First some review of Day 1
• We covered a lot of ground yesterday
• Please ask if you have any questions
Lists are created with [ ]
Use tab to find out what ‘methods’ are available
Getting help on functions
Asking a function or module for help
Start ipython
If tests and indentation matters
for loops
Matplot lib
1st plot
2nd plot
Discreet samples form a sine
wave
Reading files – Step 1
•
•
First create a file to read
Save it as data01.txt on the desktop
Get to the Desktop in IPython
Now read the file
• Finish the for loop by going by unindenting
• Each line is getting to new line characters
• Use a comma to prevent the double end line
Make a data file with some numbers
• Save as data02.txt
Read as text
How do we skip lines that start with ‘#’?
• Use if and continue
Now we need to get these values to be numbers
• The variable line still has the last line read
• How can we get the float values of “3 2.2”
Now put it all together in a script
• Use SciTE to create the file
• SciTE does not know this is python until you save the file
Run the script
Make that a function so you can reuse it!
• Use SciTE to create ‘ex04.py’
Those ‘-’ in the left column collapse code
Import ex04
Use ex04.read_y to get some data
Plot it!
Save the plot
Write some data to disk
• Use file to open a file, but tell it ‘w’ to open for writing
• write does not append a newline and only takes strings
• Close the file to make sure the data is written into the file
View the data in SciTE
Time is important for data logging
Adding documentation to modules and functions
The ex05 module now has a help