4.3 Functions with Multiple Parameters

  • maximum function that determines and returns the largest of three values.
In [1]:
def maximum(value1, value2, value3):
    """Return the maximum of three values."""
    max_value = value1
    if value2 > max_value:
        max_value = value2
    if value3 > max_value:
        max_value = value3
    return max_value
In [2]:
maximum(12, 27, 36)
Out[2]:
36
In [3]:
maximum(12.3, 45.6, 9.7)
Out[3]:
45.6
In [4]:
maximum('yellow', 'red', 'orange')
Out[4]:
'yellow'
  • We did not place blank lines above and below the if statements, because pressing return on a blank line in interactive mode completes the function’s definition.
  • May call maximum with mixed types, such as ints and floats.
In [5]:
maximum(13.5, -3, 7)
Out[5]:
13.5

Function maximum’s Definition

  • Specify multiple parameters in a comma-separated list.
  • To determine the largest value:
    • Assume that value1 contains the largest value.
    • The first if statement then tests value2 > max_value, and if this condition is True assigns value2 to max_value.
    • The second if statement then tests value3 > max_value, and if this condition is True assigns value3 to max_value.
  • Now, max_value contains the largest value.

Python’s Built-In max and min Functions

  • For many common tasks, the capabilities you need already exist in Python.
  • Built-in max and min functions know how to determine the largest and smallest of their two or more arguments:
In [6]:
max('yellow', 'red', 'orange', 'blue', 'green')
Out[6]:
'yellow'
In [7]:
min(15, 9, 27, 14)
Out[7]:
9
  • Each also can receive an iterable argument, such as a list or a string.
  • Using built-in functions or functions from the Python Standard Library’s modules rather than writing your own can reduce development time and increase program reliability, portability and performance.
  • Python’s built-in functions and modules

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