09-Built-in Functions/.ipynb_checkpoints/09-Built-in Functions Assessment Test - Solution-checkpoint.ipynb

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   "cell_type": "markdown",
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   "source": [
    "# Built-in Functions Test Solutions\n",
    "\n",
    "### For this test, you should use built-in functions and be able to write the requested functions in one line."
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 1\n",
    "\n",
    "Use map() to create a function which finds the length of each word in the phrase\n",
    "(broken by spaces) and return the values in a list.\n",
    "\n",
    "The function will have an input of a string, and output a list of integers."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "metadata": {},
   "outputs": [],
   "source": [
    "def word_lengths(phrase):\n",
    "    \n",
    "    return list(map(len, phrase.split()))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "[3, 4, 3, 3, 5, 2, 4, 6]"
      ]
     },
     "execution_count": 2,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "word_lengths('How long are the words in this phrase')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 2 \n",
    "\n",
    "Use reduce() to take a list of digits and return the number that they\n",
    "correspond to. For example, \\[1,2,3] corresponds to one-hundred-twenty-three. \n",
    "<br>*Do not convert the integers to strings!* "
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "metadata": {},
   "outputs": [],
   "source": [
    "from functools import reduce\n",
    "\n",
    "def digits_to_num(digits):\n",
    "    \n",
    "    return reduce(lambda x,y:x*10 + y,digits)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "34321"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "digits_to_num([3,4,3,2,1])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 3\n",
    "\n",
    "Use filter() to return the words from a list of words which start with a target letter."
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "metadata": {},
   "outputs": [],
   "source": [
    "def filter_words(word_list, letter):\n",
    "    \n",
    "    return list(filter(lambda word:word[0]==letter,word_list))"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['hello', 'ham', 'hi', 'heart']"
      ]
     },
     "execution_count": 6,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "words = ['hello','are','cat','dog','ham','hi','go','to','heart']\n",
    "filter_words(words,'h')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 4\n",
    "\n",
    "Use zip() and a list comprehension to return a list of the same length where each value is the two strings from\n",
    "L1 and L2 concatenated together with a connector between them. Look at the example output below:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "metadata": {},
   "outputs": [],
   "source": [
    "def concatenate(L1, L2, connector):\n",
    "    \n",
    "    return [word1+connector+word2 for (word1,word2) in zip(L1,L2)]"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['A-a', 'B-b']"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "concatenate(['A','B'],['a','b'],'-')"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 5\n",
    "\n",
    "Use enumerate() and other skills to return a dictionary which has the values of the list as keys and the index as the value. You may assume that a value will only appear once in the given list.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 9,
   "metadata": {},
   "outputs": [],
   "source": [
    "def d_list(L):\n",
    "    \n",
    "    return {key:value for value,key in enumerate(L)}"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 10,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "{'a': 0, 'b': 1, 'c': 2}"
      ]
     },
     "execution_count": 10,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "d_list(['a','b','c'])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "### Problem 6\n",
    "\n",
    "Use enumerate() and other skills from above to return the count of the number of items in the list whose value equals its index.\n"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 11,
   "metadata": {},
   "outputs": [],
   "source": [
    "def count_match_index(L):\n",
    "   \n",
    "    return len([num for count,num in enumerate(L) if num==count])"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 12,
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "4"
      ]
     },
     "execution_count": 12,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "count_match_index([0,2,2,1,5,5,6,10])"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "# Great Job!"
   ]
  }
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