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python elements:
    

• keywords
• symbols
• topics
• modules

variables:

•     case sensitive
• start with a letter not a number
• long names are ok

types and operators:

•     int
• float
• long
• complex a = (3 + 4j) #type (a)

• airthmetic operators
• assignment operators
• comparison operators: < > = >= == != 
• some have overload abilities +

casts:

•     int()
• float()
• long()
• hex() #string representation
• oct() #string rep
• str() # for printig numbers and strings

Built in constants:

• Trus
• False

Indenting counts:

•     indent 4 spaces or a tab
• : at end of line indicates start of code block
• requires next line to be indented
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• code block ends with an outdent
• check your indents!
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Program structure

• loops
• conditionals, controls
• functions
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IDLE:

•     syntex color coded
• statement completion
• written in python tkinter gui module???
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dir()

• gives you a list of the variables in the interpreter
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Comments:
    
    in line text after # is ignored
    
    text within triple quotes
    """ this is a multiline
    comment
    indentation needs to conform """
    
STRINGS:
    sequence of characters such as s = "abcdefg"
    indexed wih [] starting at [0]
    s[-1] refers to last character in string

•     negative indexing starts at last character
• use s[p:q] for string slicing
• s[3:] evaluated as "defg"
• s[:3] eevaluated as "abc" (up to but not 3)
• s[1:-2] evaluated as "bcde"  (up to but not including -2)

 VERY HANDY!
 
 STR Concatenation
 

•  first = "John"
• last = "Cleese"
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• full = first + " " + last
• sp = " "
• full = first + sp + last

"+" operator is Operand Aware

• if both sides are strings, python will concatenate
• if they are numbrs it will add them
• if you mix:  you get an error
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 immutable string:

•      if you want to change a character in a string, assign the new string to the same variable
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automatic memory management

• 21st century!
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printing:
    _ = " " # string variable names _
    print ("hello" + _ + "there")
    pi = 3.14159
    print ('The answer is ' + str(pi)) # cast float to string in order to print
    

Conditionals
elif = else if
if a>0:
elif a<0:
else:
    

rint column titles
right align degree values
limit radians to 7 character


str is a class

• see documentation + read up!
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math module

• import math
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math.sqrt(x)
math.sin(x)
math.cos(x)

use math.pi for defined constant
use math.cos(radian) to compute cosine
print cosine in 3rd column

• align cosine to decimal point
•     

import sys
sys.path.append("/u/efeibush/spline")
import cubic.py # import your own code

Collections -> arrays in other languages

List [] # ordered sequence of stuff

• looks like an array in c
• indexed from [0]
• last index is length [-1]
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• it is though a class
• with its own methods
• .append()
• .sort()
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• magic slice operator :
• magic iter() function actually __iter__()

tuple  () # n-tuple, immutable

Declare a List

• x = [14,23, 34 ,42, 50, 59]
• x.append(66)
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List methods

• append
• extend
• insert
• remove
• sort
• reverse
• index
• count
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• cList = aList + bList #concatenate lists
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ragne() function returns a list

range(stop)
range(start, stop)
range(start,stop,incr)

returns list of integres up to but not including stop

built in function
dir(__builtins__)

looping with range

• for in
  • for i in range(10):
  • for i in dayList:
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numpy.linspace

import numpy
a = numpy.linspace(1., 2.,11)
for i in a:
    
look up list techniques


store a list of radians and a list of cosines
print the lists
use a range loop instead of while


import numpy  (if you get into large arrays)
ndarray class
princeton.edu/~freibush

delete keyword

del a[3]


unpack a list into variables

name = ["abe", "lincoln"]

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first, last = name

command line arguments

• import sys
• print (sys.argv)
• sys,argv is a list
• sys.argv[0] has the name of the python lfile
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shell scripting

much better text handling than csh and bsh and shell independent

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