Python extract text from file

Working in 4k chunks would be clever, but is a bit trickier on edge-cases with re. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Asked 10 years, 5 months ago. Active 3 years, 9 months ago. Viewed 13k times. Is there a library out there that will let me do this without the burden of python's latency? Improve this question.

If you can read C, the source code for GNU strings might be helpful. It's only a few hundred lines, so it's not that bad. If you need unicode strings as well, there's that: gist. So what I need is from every block of data there are thousands of them in the file to get the part that is between the line that says "coordinates" and line that says "velocities".

I need to copy that in one file which would have number 23 No. How do I rewrite the script to do this? Or can someone please recommend some literature where I can learn this.

Sorry for the long post, but I thought it would be useful to provide a sample of data. Thank you in advance for any help with this. The middle part of line is called a list comprehension. If any of this is really unclear just ask. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams?

Collectives on Stack Overflow. Learn more. How to extract data from a text file with python script? Ask Question. Reading a full file is no big deal with small files, but generally speaking, it's not a great idea.

For one thing, if your file is bigger than the amount of available memory, you'll encounter an error. In Python, the file object is an iterator. An iterator is a type of Python object which behaves in certain ways when operated on repeatedly. For instance, you can use a for loop to operate on a file object repeatedly, and each time the same operation is performed, you'll receive a different, or "next," result. For text files, the file object iterates one line of text at a time.

It considers one line of text a "unit" of data, so we can use a for Notice that we're getting an extra line break "newline" after every line. That's because two newlines are being printed. The first one is the newline at the end of every line of our text file.

The second newline happens because, by default, print adds a linebreak of its own at the end of whatever you've asked it to print. Let's store our lines of text in a variable — specifically, a list variable — so we can look at it more closely. In Python, lists are similar to, but not the same as, an array in C or Java. A Python list contains indexed data, of varying lengths and types.

The output of this program is a little different. Instead of printing the contents of the list, this program prints our list object , which looks like this:. Here, we see the raw contents of the list. In its raw object form, a list is represented as a comma- delimited list. Much like a C or Java array, the list elements are accessed by specifying an index number after the variable name, in brackets. Index numbers start at zero — other words, the n th element of a list has the numeric index n If you're wondering why the index numbers start at zero instead of one, you're not alone.

Computer scientists have debated the usefulness of zero-based numbering systems in the past. In , Edsger Dijkstra gave his opinion on the subject, explaining why zero-based numbering is the best way to index data in computer science. You can read the memo yourself — he makes a compelling argument. We can print the first element of lines by specifying index number 0 , contained in brackets after the name of the list:.

A list object is an iterator, so to print every element of the list, we can iterate over it with for But we're still getting extra newlines. Also, after printing each line, print adds a newline of its own, unless you tell it to do otherwise. We can change this default behavior by specifying an end parameter in our print call:.

By setting end to an empty string two single quotes, with no space , we tell print to print nothing at the end of a line, instead of a newline character. We want to get rid of these, so we don't have to worry about them while we process the file.

To remove the newlines completely, we can strip them. To strip a string is to remove one or more characters, usually whitespace , from either the beginning or end of the string.

Python 3 string objects have a method called rstrip , which strips characters from the right side of a string. The English language reads left-to-right, so stripping from the right side removes characters from the end. If the variable is named mystring , we can strip its right side with mystring.

For example, "abc". When you represent a string in your program with its literal contents, it's called a string literal. You can install pip package manager in Ubuntu by running the command below:. Once you have pip manager installed, run the following command to install dependencies for Textract:. You can install pip package manager in other Linux distributions from the package manager. Alternatively, you can install pip package manager in Linux by following official installation instructions available here.

Once the pip package manager is installed, you can either use the pip command specified above or follow further installation instructions available in the official documentation of Textract only for Linux distributions other than Ubuntu. According to the official documentation of Textract, you can use it to extract text from following file formats:. To extract text from any of these supported files and show the output as stdout in terminal, run a command in the following format:.