get nth line of string in python

Question

How can you get the nth line of a string in Python 3? For example

getline(\"line1\\nline2\\nline3\",3)

Is there any way to do this

Answer 1

A more efficient solution than splitting the string would be to iterate over its characters, finding the positions of the Nth and the (N - 1)th occurence of '\n' (taking into account the edge case at the start of the string). The Nth line is the substring between those positions.

Here's a messy piece of code to demonstrate it (line number is 1 indexed):

def getLine(data, line_no):
    n = 0
    lastPos = -1
    for i in range(0, len(data) - 1):
        if data[i] == "\n":
            n = n + 1
            if n == line_no:
                return data[lastPos + 1:i]
            else:
                lastPos = i;



    if(n == line_no - 1):
        return data[lastPos + 1:]
    return "" # end of string

This is also more efficient than the solution which builds up the string one character at a time.