Click here for a little suggestion\n",
" Strategy: As usual, think how would you solve it manually, without worrying about the -1 and without worrying about which kind of loop do you use (probably starting with while is much easier). There are dozens of different ways to solve it. Do it really!!! Once you have written it, fix it for the case in which the element is not in the list, also here there are several ways for doing it. And finally convert the loop into the other type and see which one is easier in this case."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": []
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": []
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"## index method and in operator"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"In Python there exist list method **.index(e)** which accepts as parameter an element and returns the position of that element in the list. For example:"
]
},
{
"cell_type": "code",
"execution_count": 4,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"1\n"
]
}
],
"source": [
"L=[3,7,2,0]\n",
"print(L.index(7))"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Unfortunately this method gives an error whenever the element is not in the list (try please). But luckily there exist operator **in** which returns a boolean telling you whether an element is in a list and operator **not in** which returns exactly the opposite. For example:"
]
},
{
"cell_type": "code",
"execution_count": 5,
"metadata": {},
"outputs": [
{
"name": "stdout",
"output_type": "stream",
"text": [
"True\n",
"False\n",
"True\n"
]
}
],
"source": [
"L=[3,7,2,0]\n",
"print(7 in L)\n",
"print(8 in L)\n",
"print(8 not in L)"
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": []
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Now that you know these method and operators, rewrite function findElement using them instead of using a loop."
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": []
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### Union"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Define a function Union which takes as input two lists A and B and returns a list consisting in the union of the two lists without insering the duplicated elements twice. The function must skip also the duplicated elements in the same list.\n",
"\n",
"For example, Union([1,2,3,4],[4,9,2,7]) should return [1,2,3,4,9,7] and Union([1,1,1,2],[3,3,3,2]) should return [1,2,3]\n",
"\n",
" Strategy: As always, think at how would you, human, solve it on paper. Write down all the steps slowly, one by one, carefully, with easy steps that a stupid computer can do using the tools described above without any superior knowledge or intuition. Do it really, or you will produce a mess or a highly inefficient program. "
]
},
{
"cell_type": "code",
"execution_count": null,
"metadata": {},
"outputs": [],
"source": []
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"Determine **Union**'s complexity supposing that the two lists have length N and M.\n",
"\n",
"Supposing that checking whether element x in L has a complexity equal to len(L) comparisons (you are not required to use the in operator, I write here its complexity in case you do), while for x in L does not have any complexity (in fact in this case it goes through the elements and it is much easier that a x in L). "
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"..."
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"..."
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"..."
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"### splitting strings"
]
},
{
"cell_type": "markdown",
"metadata": {},
"source": [
"DIFFICULT and OPTIONAL\n",
"\n",
"Without using the .split() method, define a function splitString that takes as input a string and splits it at any ortographic symbol (space, comma, point, question mark, exclamation mark, semicolon, colon). It returns the split words into a list.\n",
" Strategy: after having thought at the problem, if you can't come up with a working algorithm click below to reveal it. I said after having thought\n",
"
Write two functions, one which uses while loop and another one which uses for loop.\n",
"
Do not use the .index(< Number>) method and do not use the in operator to check whether something is inside the list (you may still use it for a for loop).\n",
" \n",
"For example, findElement([\"Albert\",\"John\",\"Mara\"],\"Mara\") returns 2 and find([7,0,\"blabla\",6.7],\"bloblo\") returns -1.\n",
"\n",
"
For example: splitString(\"This is my day! Why? Not: this isn't\") returns [\"This\",\"is\",\"my\",\"day\",\"Why\",\"Not\",\"this\",\"isn't\"]\n",
"