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8. Python - Numbers

8. Python - Numbers. Number data types store numeric values. They are immutable data types, which means that changing the value of a number data type results in a newly allocated object. Number objects are created when you assign a value to them. For example: var1 = 1 var2 = 10

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8. Python - Numbers

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  1. 8. Python - Numbers • Number data types store numeric values. They are immutable data types, which means that changing the value of a number data type results in a newly allocated object. • Number objects are created when you assign a value to them. For example: var1 = 1 var2 = 10 • You can also delete the reference to a number object by using the del statement. The syntax of the del statement is: del var1[,var2[,var3[....,varN]]]] You can delete a single object or multiple objects by using the del statement. For example: del var del var_a, var_b

  2. Python supports four different numerical types: • int (signed integers): often called just integers or ints, are positive or negative whole numbers with no decimal point. • long (long integers ): or longs, are integers of unlimited size, written like integers and followed by an uppercase or lowercase L. • float (floating point real values) : or floats, represent real numbers and are written with a decimal point dividing the integer and fractional parts. Floats may also be in scientific notation, with E or e indicating the power of 10 (2.5e2 = 2.5 x 102 = 250). • complex (complex numbers) : are of the form a + bJ, where a and b are floats and J (or j) represents the square root of -1 (which is an imaginary number). a is the real part of the number, and b is the imaginary part. Complex numbers are not used much in Python programming.

  3. Number Type Conversion: • Type int(x)to convert x to a plain integer. • Type long(x) to convert x to a long integer. • Type float(x) to convert x to a floating-point number. • Type complex(x) to convert x to a complex number with real part x and imaginary part zero. • Type complex(x, y) to convert x and y to a complex number with real part x and imaginary part y. x and y are numeric expressions

  4. Mathematical Functions:

  5. Random Number Functions:

  6. Trigonometric Functions:

  7. Mathematical Constants:

  8. 9. Python - Strings • Strings are amongst the most popular types in Python. We can create them simply by enclosing characters in quotes. Python treats single quotes the same as double quotes. • Creating strings is as simple as assigning a value to a variable. For example: var1 = 'Hello World!' var2 = "Python Programming"

  9. Accessing Values in Strings: • Python does not support a character type; these are treated as strings of length one, thus also considered a substring. • To access substrings, use the square brackets for slicing along with the index or indices to obtain your substring: • Example: var 1 = 'Hello World!' var2 = "Python Programming" print "var1[0]: ", var1[0] print "var2[1:5]: ", var2[1:5] This will produce following result: var1[0]: H var2[1:5]: ytho

  10. Updating Strings: • You can "update" an existing string by (re)assigning a variable to another string. The new value can be related to its previous value or to a completely different string altogether. • Example: var1 = 'Hello World!' print "Updated String :- ", var1[:6] + 'Python' This will produce following result: Updated String :- Hello Python

  11. Escape Characters:

  12. String Special Operators: Assume string variable a holds 'Hello' and variable b holds 'Python' then:

  13. String Formatting Operator:

  14. Other supported symbols and functionality are listed in the following table:

  15. Triple Quotes: • Python's triple quotes comes to the rescue by allowing strings to span multiple lines, including verbatim NEWLINEs, TABs, and any other special characters. • The syntax for triple quotes consists of three consecutive single or double quotes. para_str = """this is a long string that is made up of several lines and non-printable characters such as TAB ( \t ) and they will show up that way when displayed. NEWLINEs within the string, whether explicitly given like this within the brackets [ \n ], or just a NEWLINE within the variable assignment will also show up. """ print para_str;

  16. Raw String: • Raw strings don't treat the backslash as a special character at all. Every character you put into a raw string stays the way you wrote it: print 'C:\\nowhere' This would print following result: C:\nowhere Now let's make use of raw string. We would put expression in r'expression' as follows: print r'C:\\nowhere' This would print following result: C:\\nowhere

  17. Unicode String: • Normal strings in Python are stored internally as 8-bit ASCII, while Unicode strings are stored as 16-bit Unicode. This allows for a more varied set of characters, including special characters from most languages in the world. I'll restrict my treatment of Unicode strings to the following: print u'Hello, world!' This would print following result: Hello, world!

  18. Built-in String Methods:

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