Empty list and appending, or list(convert_str)?

timings.ipynb

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  {
   "cells": [
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "def to_rna_string(convert_str):\n",
      "\n",
      "    # Dict of values that require replacing\n",
      "    replaceValues = {'G': 'C', 'C': 'G', 'T': 'A', 'A': 'U'}\n",
      "\n",
      "    # Convert input string to list of characters\n",
      "    newStr = list(convert_str)\n",
      "\n",
      "    # Iterate through list of char and populate replace list\n",
      "    for i in range(0,len(convert_str)):\n",
      "        newStr[i] = replaceValues[convert_str[i]]\n",
      "\n",
      "    # Return new list as string\n",
      "    return \"\".join(newStr)\n",
      "    \n",
      "def to_rna_list(convert_str):\n",
      "\n",
      "    # Dict of values that require replacing\n",
      "    replaceValues = {'G': 'C', 'C': 'G', 'T': 'A', 'A': 'U'}\n",
      "\n",
      "    # Convert input string to list of characters\n",
      "    newStr = []\n",
      "    \n",
      "    # Iterate through list of char and populate replace list\n",
      "    for i in range(0,len(convert_str)):\n",
      "        newStr.append(replaceValues[convert_str[i]])\n",
      "\n",
      "    # Return new list as string\n",
      "    return \"\".join(newStr)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 1
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "import random\n",
      "huge = \"\".join(random.choice('ACGT') for i in range(10000000))"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [],
     "prompt_number": 18
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit -n 10 to_rna_list(huge)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10 loops, best of 3: 2.32 s per loop\n"
       ]
      }
     ],
     "prompt_number": 19
    },
    {
     "cell_type": "code",
     "collapsed": false,
     "input": [
      "%timeit -n 10 to_rna_string(huge)"
     ],
     "language": "python",
     "metadata": {},
     "outputs": [
      {
       "output_type": "stream",
       "stream": "stdout",
       "text": [
        "10 loops, best of 3: 1.86 s per loop\n"
       ]
      }
     ],
     "prompt_number": 20
    }
   ],
   "metadata": {}
  }
 ]
}