如何从python的输入文件中选择特定行

Question

Suppose I have a input Verilog file shown below:

module c17 (N1,N2,N3,N6,N7,N22,N23);
input N1,N2,N3,N6,N7;
output N22,N23;
wire N10,N11,N16,N19;
NAND2X1 NAND2_1 (.Y(N10),.A(N1),.B(N3));
NAND2X1 NAND2_2 (.Y(N11),.A(N3),.B(N6));
NAND2X1 NAND2_3 (.Y(N16),.A(N2),.B(N11));
NAND2X1 NAND2_4 (.Y(N19),.A(N11),.B(N7));
NAND2X1 NAND2_5 (.Y(N22),.A(N10),.B(N16));
NAND2X1 NAND2_6 (.Y(N23),.A(N16),.B(N19));

How do I start reading the file directly from the 5th line onwards where the string starts from NAND2x1

Answer 1

You're going to want to use the linecache module.

https://docs.python.org/2/library/linecache.html

So:

import linecache

line = linecache.getline('myfile.txt', 5)

You don't have to open the file as with open() .

Answer 2

You can read() the file into a list and slice it, for example:

with open(file, 'r') as f:
    data = f.read().splitlines()[4:]
    for line in data:
       # your code

You can also use f.readlines() but then you will have to use .rstrip() when processing each line to remove new line character.