{
"cells": [
{
"cell_type": "markdown",
"id": "f3c6c7f0",
"metadata": {},
"source": [
"# Positional and Keyword Arguments"
]
},
{
"cell_type": "markdown",
"id": "3f0cbd3a",
"metadata": {},
"source": [
"## Posisional Arguments\n",
"\n",
"Most common way of assigning arguments to parameters: via the **order** in which they are passed.\n",
"\n",
"i.e. their **position**"
]
},
{
"cell_type": "code",
"execution_count": 39,
"id": "09e8fbbd",
"metadata": {},
"outputs": [],
"source": [
"def my_func(a, b):\n",
" print(f\"{a=}, {b=}\")"
]
},
{
"cell_type": "code",
"execution_count": 40,
"id": "350e86db",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=10, b=20\n"
]
}
],
"source": [
"my_func(10, 20)"
]
},
{
"cell_type": "code",
"execution_count": 41,
"id": "d7ab7b4a",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=20, b=10\n"
]
}
],
"source": [
"my_func(20, 10)"
]
},
{
"cell_type": "code",
"execution_count": 42,
"id": "8d04e41a",
"metadata": {},
"outputs": [
{
"ename": "TypeError",
"evalue": "my_func() missing 1 required positional argument: 'b'",
"output_type": "error",
"traceback": [
"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
"\u001b[0;31mTypeError\u001b[0m Traceback (most recent call last)",
"Cell \u001b[0;32mIn[42], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmy_func\u001b[49m\u001b[43m(\u001b[49m\u001b[38;5;241;43m1\u001b[39;49m\u001b[43m)\u001b[49m\n",
"\u001b[0;31mTypeError\u001b[0m: my_func() missing 1 required positional argument: 'b'"
]
}
],
"source": [
"my_func(1)"
]
},
{
"cell_type": "code",
"execution_count": 43,
"id": "c7676e7d",
"metadata": {},
"outputs": [
{
"ename": "TypeError",
"evalue": "my_func() takes 2 positional arguments but 3 were given",
"output_type": "error",
"traceback": [
"\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
"\u001b[0;31mTypeError\u001b[0m Traceback (most recent call last)",
"Cell \u001b[0;32mIn[43], line 1\u001b[0m\n\u001b[0;32m----> 1\u001b[0m \u001b[43mmy_func\u001b[49m\u001b[43m(\u001b[49m\u001b[38;5;241;43m1\u001b[39;49m\u001b[43m,\u001b[49m\u001b[43m \u001b[49m\u001b[38;5;241;43m2\u001b[39;49m\u001b[43m,\u001b[49m\u001b[43m \u001b[49m\u001b[38;5;241;43m3\u001b[39;49m\u001b[43m)\u001b[49m\n",
"\u001b[0;31mTypeError\u001b[0m: my_func() takes 2 positional arguments but 3 were given"
]
}
],
"source": [
"my_func(1, 2, 3)"
]
},
{
"cell_type": "markdown",
"id": "e58bf53c",
"metadata": {},
"source": [
"## Default Values\n",
"\n",
"A positional arguments can be made **optional** by specifying a **default value** for the corresponding parameter."
]
},
{
"cell_type": "code",
"execution_count": 20,
"id": "74884f73",
"metadata": {},
"outputs": [],
"source": [
"def my_func(a, b=100):\n",
" print(f\"{a=}, {b=}\")"
]
},
{
"cell_type": "code",
"execution_count": 21,
"id": "8cc20a28",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=10, b=20\n"
]
}
],
"source": [
"my_func(10, 20)"
]
},
{
"cell_type": "code",
"execution_count": 22,
"id": "ba60ec0b",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=5, b=100\n"
]
}
],
"source": [
"my_func(5)"
]
},
{
"cell_type": "markdown",
"id": "51220d35",
"metadata": {},
"source": [
"Consider a case where we have three arguments, and we want to make one of theme optional:"
]
},
{
"cell_type": "markdown",
"id": "fdd35227",
"metadata": {},
"source": [
"```python\n",
"def my_func(a, b=100, c):\n",
" pass\n",
"```\n",
"\n",
"How would we call this function without specifying a value for the second parameters?\n",
"\n",
"```python\n",
"my_func(5, 25) ???\n",
"```"
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "5a972c98",
"metadata": {},
"outputs": [
{
"ename": "SyntaxError",
"evalue": "non-default argument follows default argument (983498564.py, line 1)",
"output_type": "error",
"traceback": [
"\u001b[0;36m Cell \u001b[0;32mIn[6], line 1\u001b[0;36m\u001b[0m\n\u001b[0;31m def my_func(a, b=100, c):\u001b[0m\n\u001b[0m ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m non-default argument follows default argument\n"
]
}
],
"source": [
"def my_func(a, b=100, c):\n",
" pass"
]
},
{
"cell_type": "markdown",
"id": "d09662c8",
"metadata": {},
"source": [
"If a positional parameter is defined with a didault value\n",
" \n",
"**every** positional parameter after it\n",
"\n",
"**must** also be given a difault value."
]
},
{
"cell_type": "code",
"execution_count": 23,
"id": "c525980e",
"metadata": {},
"outputs": [],
"source": [
"def my_func(a, b=5, c=10):\n",
" print(f\"{a=}, {b=}, {c=}\")"
]
},
{
"cell_type": "code",
"execution_count": 24,
"id": "f2bfbc75",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=5, c=10\n"
]
}
],
"source": [
"my_func(1)"
]
},
{
"cell_type": "code",
"execution_count": 25,
"id": "1b9d29c4",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=2, c=10\n"
]
}
],
"source": [
"my_func(1, 2)"
]
},
{
"cell_type": "code",
"execution_count": 26,
"id": "a59a2517",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=2, c=3\n"
]
}
],
"source": [
"my_func(1, 2, 3)"
]
},
{
"cell_type": "markdown",
"id": "0aa7a2c3",
"metadata": {},
"source": [
"But what if we want to specify $1^{st}$ and $3^{rd}$ arguments, but omit the $2^{nd}$ argument?\n",
"\n",
"i.e. we want to specify values for `a` and `c`, but let `b` take on its difault value?"
]
},
{
"cell_type": "markdown",
"id": "2ae0f362",
"metadata": {},
"source": [
"## Keyword Arguments (named argumnets)"
]
},
{
"cell_type": "code",
"execution_count": 27,
"id": "a80ba0f7",
"metadata": {},
"outputs": [],
"source": [
"def my_func(a, b=5, c=10):\n",
" print(f\"{a=}, {b=}, {c=}\")"
]
},
{
"cell_type": "code",
"execution_count": 28,
"id": "55dc2a6a",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=5, c=2\n"
]
}
],
"source": [
"my_func(a=1, c=2)"
]
},
{
"cell_type": "code",
"execution_count": 29,
"id": "81bb6427",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=5, c=2\n"
]
}
],
"source": [
"my_func(1, c=2)"
]
},
{
"cell_type": "markdown",
"id": "759ca484",
"metadata": {},
"source": [
"Positional arguments can, **optionally**, be specified by using the parameter name.\n",
"\n",
"Whether or not the parameters have default values"
]
},
{
"cell_type": "code",
"execution_count": 1,
"id": "a96816cf",
"metadata": {},
"outputs": [],
"source": [
"def my_func(a, b, c):\n",
" # code hare\n",
" pass"
]
},
{
"cell_type": "markdown",
"id": "a2666893",
"metadata": {},
"source": [
"```python\n",
"my_func(1, 2, 3)\n",
"my_func(1, 2, c=3)\n",
"my_func(a=1, b=2, c=3)\n",
"my_func(c=3, a=1, b=2)\n",
"```\n",
"\n",
"`a = 1`, `b = 2`, `c = 3`"
]
},
{
"cell_type": "markdown",
"id": "4df3ee0e",
"metadata": {},
"source": [
"But once you use a named argument, all parameters **thereafter must** be named too."
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "dae4ac29",
"metadata": {},
"outputs": [
{
"ename": "SyntaxError",
"evalue": "positional argument follows keyword argument (3895868150.py, line 1)",
"output_type": "error",
"traceback": [
"\u001b[0;36m Cell \u001b[0;32mIn[5], line 1\u001b[0;36m\u001b[0m\n\u001b[0;31m my_func(c=1, 2, 3)\u001b[0m\n\u001b[0m ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m positional argument follows keyword argument\n"
]
}
],
"source": [
"my_func(c=1, 2, 3)"
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "ca08245f",
"metadata": {},
"outputs": [
{
"ename": "SyntaxError",
"evalue": "positional argument follows keyword argument (2003381380.py, line 1)",
"output_type": "error",
"traceback": [
"\u001b[0;36m Cell \u001b[0;32mIn[6], line 1\u001b[0;36m\u001b[0m\n\u001b[0;31m my_func(1, b=2, 3)\u001b[0m\n\u001b[0m ^\u001b[0m\n\u001b[0;31mSyntaxError\u001b[0m\u001b[0;31m:\u001b[0m positional argument follows keyword argument\n"
]
}
],
"source": [
"my_func(1, b=2, 3)"
]
},
{
"cell_type": "code",
"execution_count": 30,
"id": "f1e2d0ba",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=2, c=3\n"
]
}
],
"source": [
"my_func(1, 2, c=3)"
]
},
{
"cell_type": "markdown",
"id": "81b049f3",
"metadata": {},
"source": [
"All arguments after the first named (keyword) arguments, must be named too.\n",
"\n",
"Default arguments may still ne omitted."
]
},
{
"cell_type": "code",
"execution_count": 33,
"id": "d1ef5052",
"metadata": {},
"outputs": [],
"source": [
"def my_func(a, b=2, c=3):\n",
" print(f\"{a=}, {b=}, {c=}\")"
]
},
{
"cell_type": "code",
"execution_count": 34,
"id": "fd0236b5",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=2, c=3\n"
]
}
],
"source": [
"my_func(1)"
]
},
{
"cell_type": "code",
"execution_count": 35,
"id": "2bc17243",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=5, c=3\n"
]
}
],
"source": [
"my_func(a=1, b=5)"
]
},
{
"cell_type": "code",
"execution_count": 36,
"id": "0a95be80",
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"a=1, b=2, c=0\n"
]
}
],
"source": [
"my_func(c=0, a=1)"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python 3 (ipykernel)",
"language": "python",
"name": "python3"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.11.4"
}
},
"nbformat": 4,
"nbformat_minor": 5
}