python read file one line
In Python implementations different from CPython, the file often isn't immediately closed, but rather at a later time, beyond your control. In Python 3.2 or above, this will throw a ResourceWarning , if enabled. Better to invest one additional line: , Note that this does not include the -n character at the end of the line, but I'm assuming you don't want it anyway (and a single-line file may not even have one). Also note that although it's pretty short and quick, it does make a copy of the, Without a little more information, it's hard to be absolutely sure… but most likely, your problem is inappropriate line endings. For example, on a modern Mac OS X system, lines in text files end with '-n' newline characters. So, when you do f, One thing that could cause that behavior would be if Python is for some reason not liking the end of line chars from the original file. To confirm that, on Linux you could use od -t a file | less , and inspect what's in there. Perhaps the file confor, Well, you throw away the file object after using it so you cannot close it. Yes, Python will eventually automatically close your file, but on its terms rather than yours. If you are just playing around in a shell or terminal, this is probably fine, becau, Reading files is incredible fast. Reading a 100MB file takes less than 0.1 seconds (see my article Reading and Writing Files with Python). Hence you should read it completely and then work with the single lines. What most answer here do is not wrong, but,The file could be very large, and you could run out of memory. Even if it's not large, it is simply a waste of memory. 2) This does not allow processing of each line as you read them. So if you process your lines after this, it is not efficient (requi, Also, another technique that I discovered works great in some applications is parallel CSV file reads all within one giant file, starting each worker at different offset into the file, rather than pre-splitting one big file into many part files. Use pyth, This is useful for smaller files where you would like to do text manipulation on the entire file, or whatever else suits you. Then there is readline which is one useful way to only read in individual line incremental amounts at a time and return them as
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 python read file one line 相關參考資料
python - open read and close a file in 1 line of code - Stack Overflow
In Python implementations different from CPython, the file often isn't immediately closed, but rather at a later time, beyond your control. In Python 3.2 or above, this will throw a ResourceWarni... https://stackoverflow.com python - Read only the first line of a file? - Stack Overflow
Note that this does not include the -n character at the end of the line, but I'm assuming you don't want it anyway (and a single-line file may not even have one). Also note that although it&#... https://stackoverflow.com Reading file in Python one line at a time - Stack Overflow
Without a little more information, it's hard to be absolutely sure… but most likely, your problem is inappropriate line endings. For example, on a modern Mac OS X system, lines in text files end ... https://stackoverflow.com Python reading the entire file as one line - Stack Overflow
One thing that could cause that behavior would be if Python is for some reason not liking the end of line chars from the original file. To confirm that, on Linux you could use od -t a file | less , a... https://stackoverflow.com Python opening and reading files one liner - Stack Overflow
Well, you throw away the file object after using it so you cannot close it. Yes, Python will eventually automatically close your file, but on its terms rather than yours. If you are just playing arou... https://stackoverflow.com file - Reading specific lines only (Python) - Stack Overflow
Reading files is incredible fast. Reading a 100MB file takes less than 0.1 seconds (see my article Reading and Writing Files with Python). Hence you should read it completely and then work with the s... https://stackoverflow.com string - In Python, how do I read a file line-by-line into a list? - Stack ...
The file could be very large, and you could run out of memory. Even if it's not large, it is simply a waste of memory. 2) This does not allow processing of each line as you read them. So if you pr... https://stackoverflow.com How to a read large file, line by line in python - Stack Overflow
Also, another technique that I discovered works great in some applications is parallel CSV file reads all within one giant file, starting each worker at different offset into the file, rather than pr... https://stackoverflow.com Read a File Line-by-Line in Python - Stack Abuse
This is useful for smaller files where you would like to do text manipulation on the entire file, or whatever else suits you. Then there is readline which is one useful way to only read in individual... http://stackabuse.com |