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I have a very large text file and only want read a certain amount of characters because reading the entire file would take a lot of time.

I found solutions to only read a certain number of lines but that didn't change anything in my case since all the characters are in one line.

DwarfDev
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    `with open(file) as f: chars = f.read(n)` – erip Aug 30 '22 at 15:08
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    If you need to read a certain number of *bytes*, it's trivial: `with open("largefile.txt") as f: x = f.read(6)`. If you need a number of Unicode characters that might be encoded using multiple bytes, it's trickier, but you can start by reading 24 bytes (which is the most 6 characters could occupy). – chepner Aug 30 '22 at 15:08
  • that is just it: pass the desired amiount of characters to the ".read" call, as the first parameter. – jsbueno Aug 30 '22 at 15:09
  • (I had binary on the brain; when you open the file in text mode, `read` returns characters, not bytes.) – chepner Aug 30 '22 at 15:14
  • Hmm... [How to read x characters at a time from a file in python?](https://stackoverflow.com/q/61393309/364696) isn't technically a duplicate, but I suspect no duplicate exists because this is too trivial to be worth a question ([the docs](https://docs.python.org/3/library/io.html) are quite clear). This was en route to being closed for other reasons (there were two votes to close for being off-topic before I duped it), so I'm inclined to leave it; the answer is implicit in the duplicate, even if it isn't precisely the same question. – ShadowRanger Aug 30 '22 at 15:19
  • @ShadowRanger IMO this question is a useful one, not a straightforward duplicate, and the docs are confusing because the relevant information is only presented as part of the `io` module, which most people don't use explicitly when reading from a file. (I wonder why the docs don't have a clear page for the Python `file` object. Googling this topic just takes you to the tutorial. It takes some work to find out that their interfaces are defined in the `io` module.) – Stuart Aug 30 '22 at 20:03
  • @Stuart: `file` isn't a type in Python 3 (the old `file` type in Python 2 went away in favor of `open`, which on Python 3 is an alias for the `io.open` function, which returns different types with different layering depending on the arguments passed). The result of `open` is one of `io.FileIO` (for unbuffered binary mode), `io.Buffered*` (for buffered binary modes) or `io.TextIOWrapper` (for text mode). `read` is documented on the appropriate `*Base` ABC. – ShadowRanger Aug 30 '22 at 20:26

1 Answers1

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read() takes a numeric argument specifying how many characters* to read.

with open('your_file.txt') as file:
    print(file.read(42))  # prints the first 42 characters of the file

* Note that it's "characters" if the file is a text file (characters might be multibyte, depending on the encoding), and "bytes" if the file is opened in binary mode.

Samwise
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