Python Programming Notes PDF

**Strings** Main escape characters used in Python: Code Result \\\" Double Quotes \\\' Single Quote \\\\ Backslash \\n New Line \\t Tab \\b Backspace print(\"Our logo \"GO BEARS GO\" \") -- error print(\"Our logo \\\"GO BEARS GO\\\" \") Output: Our logo \"GO BEARS GO\" **Type Casting**...

**Strings** Main escape characters used in Python: Code Result \\\" Double Quotes \\\' Single Quote \\\\ Backslash \\n New Line \\t Tab \\b Backspace print(\"Our logo \"GO BEARS GO\" \") -- error print(\"Our logo \\\"GO BEARS GO\\\" \") Output: Our logo \"GO BEARS GO\" **Type Casting** **int()** will return the value between the parentheses as an integer (rounding down if necessary) **float()** will return the value between the parentheses as a float (adding.0 if necessary) **str()** will return the value between the parentheses as a string For example: **int(3/2) -\> 1** **float(3) -\> 3.0** **str(5) -\> \"5\"** **int(\"7\") -\> 7** **int(\"abc\")-\> error** **print(\"sum is\" + 15) --\> error** **print(\"sum is\" + str(15)) --\> no errors** **print(\"3\"\*5) --\> \"33333\"** **print( int(\"3\") \*5) --\> 15** **Using strings** **Variables:** Variables are named locations in memory for the storage of data of a specified type. What variable types do we know about so far? Int (Integers) Str (String) We will add float to this list. A float is a real number. In Python, the compiler will declare a variable "on the fly" This is bad form! I expect all variables to be "declared" before they are used at the top of the program. **Rules for variables:** A variable name cannot contain spaces The first character cannot be any digit. It must be one of the letters a through z, A through Z, or an underscore \_. The rest can be the combination of letters a through z or A through *Z,* the digits 0 through 9 Can not use any special symbols inside a variable name except for \_ Uppercase and lowercase characters are distinct You can't use words reserved for Python. For example you can't use the word 'print' as a variable. It is a keyword When naming a variable, give it a name that is descriptive of its role **Variable Types:** Integer -- int, stores integer numbers String -- str, stores letters and words Floating point -- float, stores decimals Boolean -- True or False **What var type it should be:** Your age Your name Pi The distance between Toronto and Montreal Today's Date The number of apples in a bushel **Math Operators:** Cannot divide by zero Math sqrt- returns the square root of a number math.pi The mathematical constant π = 3.141592\..., to available precision. x=2\* math.pi\*15 \>\>\>math.pi 3.141592653589793 math.ceil(x) Return the ceiling of x, the smallest integer greater than or equal to x math.ceil(3.5) 4 math.ceil(-5.3) -5 🡪🡪 math.fabs(x) Return the absolute value of x. math.factorial(x) Return x factorial. Raises ValueError if x is not integral or is negative. math. factorial(3) 6 math. factorial(4) 24 🡪🡪 math.floor(x) Return the floor of x, the largest integer less than or equal to x. math. floor (3.5) 3 math. floor (-5.3) -6 🡪🡪 math.pow(x, y) Return x raised to the power y. math. pow (2,3) 8 🡪 math.sqrt(x) Return the square root of x. math.cos(x) Return the cosine of x radians. math.hypot(x, y) Return the Euclidean norm, sqrt(x\*x + y\*y). This is the length of the vector from the origin to point (x, y). math.sin(x) Return the sine of x radians. math.tan(x) Return the tangent of x radians. math.degrees(x) Converts angle x from radians to degrees. math.radians(x) Converts angle x from degrees to radians.