{"id":19,"date":"2016-01-06T15:56:10","date_gmt":"2016-01-06T15:56:10","guid":{"rendered":"http:\/\/mr-west.uk\/python\/?page_id=19"},"modified":"2022-12-01T15:24:42","modified_gmt":"2022-12-01T15:24:42","slug":"saving-to-text-files","status":"publish","type":"page","link":"https:\/\/learnlearn.uk\/python\/saving-to-text-files\/","title":{"rendered":"Python Reading from \/ Writing to Text Files"},"content":{"rendered":"
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Read file<\/h2>\n
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Reading a file and print each line<\/h3>\n

Often you will want to read in data from a text file and do something with each line of data. For this we can use the in-built open function.<\/p>\n

Let’s say we have text file that contains 3 words, one on each line. We can use open() to read the file contents into Python
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We can load this file and print out each line in the file:<\/p>\n

Code<\/strong><\/p>\n

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f  =<\/span> open<\/span>('animals.txt'<\/span>,'r'<\/span>)\r\nfor<\/span> animal in<\/span> f:\r\n    print<\/span>(animal.<\/span>strip('<\/span>\\n<\/span>'<\/span>))<\/pre>\n<\/div>\n
Output<\/strong><\/p>\n
cat dog mouse<\/pre>\n
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  • Note how when we open a file for reading we use ‘r’ read mode.<\/li>\n<\/ul>\n
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    Reading a single line file<\/strong><\/p>\n
    If your file only has a single line and you want to read it in, then use readline()<\/p>\n
    <\/p>\n
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    f =<\/span> open<\/span>('highscore.txt'<\/span>,'r'<\/span>)\r\nhigh_score =<\/span> f.<\/span>readline()\r\nprint<\/span>('High Score:'<\/span>,high_score)\r\n<\/pre>\n<\/div>\n\n<\/div>
    Read to list<\/h2>\n
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    Reading data from a text file into a list<\/h3>\n
    Most of the time you will want to read the file into a list. This is simple and easy to achieve:<\/p>\n
    <\/p>\n
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    f  =<\/span> open<\/span>('animals.txt'<\/span>,'r'<\/span>)\r\n\r\nanimal_list =<\/span> []\r\n\r\nfor<\/span> animal in<\/span> f:\r\n    animal_list.<\/span>append(animal.<\/span>strip('<\/span>\\n<\/span>'<\/span>))\r\n\r\nprint<\/span>(animal_list)\r\n<\/pre>\n<\/div>\n
    Output:<\/strong><\/p>\n
    ['cat', 'dog', 'mouse']<\/pre>\n\n<\/div>
    Write<\/h2>\n
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    Writing to Text Files<\/h3>\n
    Sometimes we want to save data to a file. Here we open the file in ‘w’ write mode and use the write() method.<\/p>\n
    <\/p>\n
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    f =<\/span> open<\/span>('birds.txt'<\/span>,'w'<\/span>)\r\nbirds =<\/span> [\"robin\"<\/span>,\"sparrow\"<\/span>,\"eagle\"<\/span>]\r\n\r\nfor<\/span> bird in<\/span> birds:\r\n    f.<\/span>write(bird +<\/span> '<\/span>\\n<\/span>'<\/span>)\r\n\r\nf.<\/span>close()<\/pre>\n<\/div>\n
    Output file:<\/strong><\/p>\n
    \"\"<\/p>\n
    Notes<\/strong><\/p>\n
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    • If you want to completely overwrite any data previously saved into the file use ‘w’. If you just want to append(add) to the existing contents of the file use ‘w’<\/li>\n
    • make sure you call f.close() after you have finishing writing all the data otherwise it won’t save the changes.<\/li>\n<\/ul>\n
       <\/p>\n\n<\/div>
      Videos<\/h2>\n
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      Reading Text Files Video Tutorial
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