Given a large file (hundreds of MB) how would I use Python to quickly read the content between a specific start and end index within the file? Show
Essentially, I'm looking for a more efficient way of doing:
asked Mar 26, 2013 at 18:36
You can
That will only read that data that you're looking for. answered Mar 26, 2013 at 18:38
Dan LecocqDan Lecocq 3,27326 silver badges22 bronze badges 3 This is my solution with variable width encoding. My CSV file contains a dictionary where each row is a new item.
answered Jun 28, 2019 at 14:05
2 Summary: in this tutorial, you learn various ways to read text files in Python. TL;DRThe following shows how to read all texts from the
Steps for reading a text file in PythonTo read a text file in Python, you follow these steps:
1) open() functionThe
The If the program and file are in the same folder, you need to specify only the filename of the file. Otherwise, you need to include the path to the file as well as the filename. To specify the path to the file, you use the forward-slash ( For example, if the file The
For example, to open a file whose name is
The 2) Reading text methodsThe file object provides you with three methods for reading text from a text file:
3) close() methodThe file that you open will remain open until you close it using the It’s important to close the file that is no longer in use for the following reasons:
The following
shows how to call the
To close the file automatically without calling the
In practice, you’ll use the Reading a text file examplesWe’ll use the-zen-of-python.txt file for the demonstration. The following example illustrates how to use the
Output:
The following example uses the
Output:
The reason you see a blank line after each line from a file is that each line in the text file has a newline character (\n). To remove the blank line, you can use
the
The following example shows how to use the
Output:
A more concise way to read a text file line by lineThe
This is a more concise way to read a text file line by line. Read UTF-8 text filesThe code in the previous examples works fine with ASCII text files. However, if you’re dealing with other languages such as Japanese, Chinese, and Korean, the text file is not a simple ASCII text file. And it’s likely a UTF-8 file that uses more than just the standard ASCII text characters. To open a UTF-8 text file, you need to pass the For the demonstration, you’ll use the following The following shows how to loop through the
Output: Summary
Did you find this tutorial helpful ? How do I read a specific part of a file in Python?You can seek into the file the file and then read a certain amount from there. Seek allows you to get to a specific offset within a file, and then you can limit your read to only the number of bytes in that range. That will only read that data that you're looking for.
How do I extract specific portion of a text file using Python?How to extract specific portions of a text file using Python. Make sure you're using Python 3.. Reading data from a text file.. Using "with open". Reading text files line-by-line.. Storing text data in a variable.. Searching text for a substring.. Incorporating regular expressions.. Putting it all together.. How do you read the contents of a file in Python?To read, use the read ( r ) mode:. filename = '/Users/flavio/test.txt' file = open(filename, 'r') #or file = open(filename, mode='r'). content = file. read(). line = file. readline(). file. close(). How do I read the second line of a file in Python?Method 1: fileobject.readlines()
A file object can be created in Python and then readlines() method can be invoked on this object to read lines into a stream.
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