Work_with_file_in_colab.ipynb

{
  "nbformat": 4,
  "nbformat_minor": 0,
  "metadata": {
    "colab": {
      "name": "Work_with_file_in_colab.ipynb",
      "provenance": []
    },
    "kernelspec": {
      "name": "python3",
      "display_name": "Python 3"
    },
    "language_info": {
      "name": "python"
    }
  },
  "cells": [
    {
      "cell_type": "markdown",
      "source": [
        "This command allows you to upload files into Colab"
      ],
      "metadata": {
        "id": "d6sGRG-UCB8b"
      }
    },
    {
      "cell_type": "code",
      "execution_count": 4,
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/",
          "resources": {
            "http://localhost:8080/nbextensions/google.colab/files.js": {
              "data": 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              "ok": true,
              "headers": [
                [
                  "content-type",
                  "application/javascript"
                ]
              ],
              "status": 200,
              "status_text": ""
            }
          },
          "height": 39
        },
        "id": "SvT8xsBPS4XV",
        "outputId": "6a9200df-04f7-4667-d5f5-2d5ec4c1c815"
      },
      "outputs": [
        {
          "output_type": "display_data",
          "data": {
            "text/plain": [
              "<IPython.core.display.HTML object>"
            ],
            "text/html": [
              "\n",
              "     "
            ]
          },
          "metadata": {}
        }
      ],
      "source": [
        "from google.colab import files\n",
        "uploaded = files.upload()"
      ]
    },
    {
      "cell_type": "markdown",
      "source": [
        " File Handling: \n",
        " \n",
        " Create, write, append (in this mode, the data will be inserted at the end of the file), reading content in a file."
      ],
      "metadata": {
        "id": "OIX8s0aDJDCx"
      }
    },
    {
      "cell_type": "code",
      "source": [
        "s = \"“There are two motives for reading a book; one, that you enjoy it; the other, that you can boast about it. Bertrand Russell \\n\"\n",
        "fshort = open(\"prova.txt\", \"w\") # \"w\" : Opens a file for writing. Creates a new file if it does not exist or truncates the file if it exists.\n",
        "fshort.write(s) \n",
        "fshort.close()"
      ],
      "metadata": {
        "id": "xOZrE0h0D816"
      },
      "execution_count": 11,
      "outputs": []
    },
    {
      "cell_type": "code",
      "source": [
        "with open(\"prova.txt\",\"a\") as f: # \"a\" :Opens a file for appending at the end of the file. Creates a new file if it does not exist.\n",
        "  for i in range(3): # add 3 new line in file   \n",
        "       f.write(\"\\****!°°|*|°°!*****\\n\")\n",
        "       #print(f.tell())    # get the current file position         \n",
        "  f.close    "
      ],
      "metadata": {
        "id": "8mzuaxs3Eddv"
      },
      "execution_count": 12,
      "outputs": []
    },
    {
      "cell_type": "code",
      "source": [
        "with open(\"prova.txt\",\"r\") as f:   \n",
        "    contents = f.read(6) # read the first 6 characters\n",
        "    contents = f.read(4) #  read the next 4 characters\n",
        "    #print(f.tell())      # get the current file position       \n",
        "    contents = f.read()  # read the rest of file till end \n",
        "    contents = f.read()  # further reading returns empty sting\n",
        "    f.seek(0)            # bring file cursor to initial position\n",
        "    contents = f.read()  # read the entire file \n",
        "    f.close()        \n",
        "print(contents)  "
      ],
      "metadata": {
        "id": "BnJQru9vHgtV"
      },
      "execution_count": null,
      "outputs": []
    },
    {
      "cell_type": "markdown",
      "source": [
        "A simple way to write at the specific position in a file."
      ],
      "metadata": {
        "id": "1EDCHphCFcN_"
      }
    },
    {
      "cell_type": "code",
      "source": [
        "mystring = ' #-#-#-#-# and  '\n",
        "pos = 10\n",
        "\n",
        "with open('prova.txt', 'r+') as f: #  r+ : Opens a file for updating (reading and writing)\n",
        "    contents = f.read()\n",
        "    contents = contents[:pos] + mystring + contents[pos + 1:] # counts 10 characters\n",
        "    f.seek(0) # 0: sets the reference point at the beginning of the file\n",
        "    f.truncate()\n",
        "    f.write(contents)\n",
        "    f.close()   "
      ],
      "metadata": {
        "id": "uxQ6W1mRFSx7"
      },
      "execution_count": 21,
      "outputs": []
    },
    {
      "cell_type": "code",
      "source": [
        "with open(\"prova.txt\",\"r\") as f:   \n",
        "    contents = f.read()  # read the entire file \n",
        "    f.close()        \n",
        "print(contents)  "
      ],
      "metadata": {
        "id": "gWR6AVbGH04p"
      },
      "execution_count": null,
      "outputs": []
    },
    {
      "cell_type": "markdown",
      "source": [
        "Copy the file prova.txt to the file prova1.txt:"
      ],
      "metadata": {
        "id": "mIBY25fWI1LA"
      }
    },
    {
      "cell_type": "code",
      "source": [
        "with open('prova.txt','r') as f:\n",
        "    with open('prova1.txt','w') as wf:\n",
        "          for line in f:\n",
        "                wf.write(line)"
      ],
      "metadata": {
        "id": "ZhXl6JymIQJs"
      },
      "execution_count": 24,
      "outputs": []
    },
    {
      "cell_type": "markdown",
      "source": [
        "Create a file with the contents present in the cell:"
      ],
      "metadata": {
        "id": "HRjq2NZAKEwI"
      }
    },
    {
      "cell_type": "code",
      "source": [
        "%%writefile list_books.py \n",
        "\n",
        "import sys\n",
        "           \n",
        "#print(\"\\n Name of file: \")\n",
        "#print(sys.argv[0])\n",
        "\n",
        "\n",
        "l = ['None','Amlet','A History of Western Philosophy','Crime and Punishment','Journey to the End of the Night']\n",
        "\n",
        "def book_choice(nn):\n",
        "    if 0 < nn <= 4:\n",
        "      return l[nn]\n",
        "    else:\n",
        "      print(\"Out of range, insert a number from 1 to 4\")  \n",
        "\n",
        "\n",
        "n = None\n",
        "\n",
        "if len(sys.argv[1])>= 1:\n",
        "     n = sys.argv[1]\n",
        "     try:\n",
        "       n = int(n)\n",
        "     except:\n",
        "       print(\"Enter a valid integer number\")  \n",
        "     else:\n",
        "       print(book_choice(n))\n",
        "\n",
        "else:\n",
        "  print(\"None paramter in input, please repeat\")    "
      ],
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "id": "d3TJjr91KN9r",
        "outputId": "c870a1c3-5adf-4ea9-9dce-2dfe714cdc0a"
      },
      "execution_count": 29,
      "outputs": [
        {
          "output_type": "stream",
          "name": "stdout",
          "text": [
            "Overwriting list_books.py\n"
          ]
        }
      ]
    },
    {
      "cell_type": "code",
      "source": [
        "%cat list_books.py"
      ],
      "metadata": {
        "id": "uGkmXms3NZiQ"
      },
      "execution_count": null,
      "outputs": []
    },
    {
      "cell_type": "markdown",
      "source": [
        "Run the file list_books.py  "
      ],
      "metadata": {
        "id": "OA0hsJeVNwfB"
      }
    },
    {
      "cell_type": "code",
      "source": [
        "%run list_books.py 4 "
      ],
      "metadata": {
        "colab": {
          "base_uri": "https://localhost:8080/"
        },
        "id": "Mn6ZY-EVNhIv",
        "outputId": "f94d40c0-20b7-4054-ac93-eace39f6b11a"
      },
      "execution_count": 34,
      "outputs": [
        {
          "output_type": "stream",
          "name": "stdout",
          "text": [
            "Journey to the End of the Night\n"
          ]
        }
      ]
    }
  ]
}