Notebook

Positional Arguments¶

In [1]:

defmy_func(a,b,c):print("a={0}, b={1}, c={2}".format(a,b,c))

In [2]:

my_func(1,2,3)

a=1, b=2, c=3

Default Values¶

In [3]:

defmy_func(a,b=2,c=3):print("a={0}, b={1}, c={2}".format(a,b,c))

Note that once a parameter is assigned a default value, all parameters thereafter must be asigned a default value too!

For example, this will not work:

In [4]:

deffn(a,b=2,c):print(a,b,c)

 File "<ipython-input-4-2180ec769037>", line 1 def fn(a, b=2, c): ^SyntaxError: non-default argument follows default argument

In [5]:

defmy_func(a,b=2,c=3):print("a={0}, b={1}, c={2}".format(a,b,c))

In [6]:

my_func(10,20,30)

a=10, b=20, c=30

In [7]:

my_func(10,20)

a=10, b=20, c=3

In [8]:

my_func(10)

a=10, b=2, c=3

Since a does not have a default value, it must be specified:

In [9]:

my_func()

---------------------------------------------------------------------------TypeError Traceback (most recent call last) <ipython-input-9-d82eda95de40> in <module>()----> 1my_func()TypeError: my_func() missing 1 required positional argument: 'a'

Keyword Arguments (named arguments)¶

Positional arguments, can optionally, be specified using their corresponding parameter name.

This allows us to pass the arguments without using the positional assignment:

In [10]:

defmy_func(a,b=2,c=3):print("a={0}, b={1}, c={2}".format(a,b,c))

In [11]:

my_func(c=30,b=20,a=10)

a=10, b=20, c=30

In [12]:

my_func(10,c=30,b=20)

a=10, b=20, c=30

Note that once a keyword argument has been used, all arguments thereafter must also be named:

In [13]:

my_func(10,b=20,30)

 File "<ipython-input-13-ea05eeab2151>", line 1 my_func(10, b=20, 30) ^SyntaxError: positional argument follows keyword argument

However, if a parameter has a default value, it can be omitted from the argument list, named or not:

In [15]:

my_func(10,c=30)

a=10, b=2, c=30

In [16]:

my_func(a=30,c=10)

a=30, b=2, c=10

In [17]:

my_func(c=10,a=30)

a=30, b=2, c=10