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  {
   "cell_type": "markdown",
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   "metadata": {},
   "source": [
    "# Week 184 The Weekly Challenge\n",
    "# Task 1: Sequence Number\n",
    "\n",
    "You are given list of strings in the format aa9999 i.e. first 2 characters can be anything 'a-z' followed by 4 digits '0-9'.\n",
    "\n",
    "Write a script to replace the first two characters with sequence starting with '00', '01', '02' etc.\n",
    "\n",
    "Example 1\n",
    "\n",
    "```\n",
    "Input: @list = ( 'ab1234', 'cd5678', 'ef1342')\n",
    "Output: ('001234', '015678', '021342')\n",
    "```\n",
    "\n",
    "Example 2\n",
    "\n",
    "```\n",
    "Input: @list = ( 'pq1122', 'rs3334')\n",
    "Output: ('001122', '013334')\n",
    "```"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 1,
   "id": "d9ddd9d0",
   "metadata": {},
   "outputs": [],
   "source": [
    "import re"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 2,
   "id": "0346d2ba",
   "metadata": {},
   "outputs": [],
   "source": [
    "input1 = ['ab1234', 'cd5678', 'ef1342']\n",
    "output1 = ['001234', '015678', '021342']\n",
    "input2 = ['pq1122', 'rs3334']\n",
    "output2 = ['001122', '013334']"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "336541b3",
   "metadata": {},
   "source": [
    "Function to substitute the first 2 letters in a string with a given prefix:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 3,
   "id": "0b2cb0f3",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'001122'"
      ]
     },
     "execution_count": 3,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def change_prefix_string (string, prefix_string):\n",
    "    result = re.sub(r'^[a-z]{2}', prefix_string, string)\n",
    "    return result\n",
    "\n",
    "change_prefix_string(\"pq1122\", \"00\")"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "b791cddb",
   "metadata": {},
   "source": [
    "Working out how to create 0 padded prefix between 00 and 99.  Loops back to 00 after 99 if more than 100:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "id": "c7ee98bf",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "'01'"
      ]
     },
     "execution_count": 4,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "num = 1\n",
    "prefix = (num) % 100\n",
    "prefix_as_string = \"%02d\" % (prefix,)\n",
    "prefix_as_string"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "8825dd5b",
   "metadata": {},
   "source": [
    "Function to generate a list of prefixes which are zero padded:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 5,
   "id": "8e168ad7",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['00', '01', '02', '03', '04']"
      ]
     },
     "execution_count": 5,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "def generate_list_of_prefixes (number_of_prefixes):\n",
    "    list_of_prefixes = [\"%02d\" % (num % 100) for num in range(number_of_prefixes)]\n",
    "    return list_of_prefixes\n",
    "\n",
    "generate_list_of_prefixes(5)"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "564c5b35",
   "metadata": {},
   "source": [
    "Bringing everything together:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 6,
   "id": "688ef188",
   "metadata": {},
   "outputs": [],
   "source": [
    "def change_prefix_list_of_strings (los):\n",
    "    length_of_list = len(los)\n",
    "    list_of_prefixes = generate_list_of_prefixes(length_of_list)\n",
    "    result_list = [change_prefix_string(los[i], list_of_prefixes[i]) for i in range(length_of_list)]\n",
    "    return result_list"
   ]
  },
  {
   "cell_type": "markdown",
   "id": "5e899500",
   "metadata": {},
   "source": [
    "Testing the function with example lists above:"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 7,
   "id": "f2e4b48b",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['001234', '015678', '021342']"
      ]
     },
     "execution_count": 7,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "change_prefix_list_of_strings(input1)"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 8,
   "id": "b9fe98c2",
   "metadata": {},
   "outputs": [
    {
     "data": {
      "text/plain": [
       "['001122', '013334']"
      ]
     },
     "execution_count": 8,
     "metadata": {},
     "output_type": "execute_result"
    }
   ],
   "source": [
    "change_prefix_list_of_strings(input2)"
   ]
  }
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