How to read only one line from a file in python
|
Lots of other answers here, but to answer precisely the question you asked (before @MarkAmery went and edited the original question and changed the meaning): Show In other words, if you've already read in the file (as you said), and have a big block of data in memory, then to get the first line from it efficiently, do a split() on the newline character, once only, and take the first element from the resulting list. Note that this does not include
the View Discussion Improve Article Save Article View Discussion Improve Article Save Article Text files are composed of plain text content. Text files are also known as flat files or plain files. Python provides easy support to read and access the content within the file. Text files are first opened and then the content is accessed from it in the order of lines. By default, the line numbers begin with the 0th index. There are various ways to read specific lines from a text file in python, this article is aimed at discussing them. File in use: test.txt 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. This method is preferred when a single line or a range of lines from a file needs to be accessed simultaneously. It can be easily used to print lines from any random starting index to some ending index. It initially reads the entire content of the file and keep a copy of it in memory. The lines at the specified indices are then accessed. Example: Python3
Output
Method 2: linecache package The linecache package can be imported in Python and then be used to extract and access specific lines in Python. The package can be used to read multiple lines simultaneously. It makes use of cache storage to perform optimization internally. This package opens the file on its own and gets to the particular line. This package has getline() method which is used for the same. Syntax: getLine(txt-file, line_number) Example: Python3
Output : This is line 5. Method 3: enumerate() The enumerate() method is used to convert a string or a list object to a sequence of data indexed by numbers. It is then used in the listing of the data in combination with for loop. Lines at particular indexes can be accessed by specifying the index numbers required in an array. Example: Python3
Output This is line 1. This is line 8. This is line 12. How do you read a single line from a file in Python?Python readline() is a file method that helps to read one complete line from the given file. It has a trailing newline (“\n”) at the end of the string returned. You can also make use of the size parameter to get a specific length of the line.
How do I read a specific part of a file in 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 I read a specific line in a csv file in Python?Step 1: Load the CSV file using the open method in a file object. Step 2: Create a reader object with the help of DictReader method using fileobject. This reader object is also known as an iterator can be used to fetch row-wise data. Step 3: Use for loop on reader object to get each row.
How do I read the first few lines of a file in Python?Use file.. a_file = open("file_name.txt") Open "file_name.txt". number_of_lines = 3.. for i in range(number_of_lines): Print the first number_of_lines lines of a_file.. line = a_file. readline(). print(line). |
