Compare two files and remove the common lines

user_12346657 0
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I have two files. File1 with data

DF2SVT-(.CD(),.CP(clk),.D(),.SDN(),.Q(na));

OAI3DSVT-(.A1(na),.A2(),.A3(),.B(),.ZN(y));

GLHSVT-(.D(v),.E(),.Q(y));

DCCDSVT-(.I(w),.ZN(y));

and file2 with data

GLHSVT-(.D(v),.E(),.Q(y));

If the line in file2 is present in file1 then remove that line from file1 and print rest of the lines of file1. So I want output file fout as

DF2SVT-(.CD(),.CP(clk),.D(),.SDN(),.Q(na));

OAI3DSVT-(.A1(na),.A2(),.A3(),.B(),.ZN(y));

DCCDSVT-(.I(w),.ZN(y));

I know how to print common lines between two files using

for line in file1 & file2:
    if line:
       print line

But I am not getting how to remove that common line from file if match is there.

python
2 Answers

Read the lines of both files into a separate variables. Iterate over the lines of the first file, and for each of one them check if they exist on the second file, if not then save them into the first file.

with open(file1, "r") as file1:
     lines_file1 = file1.readlines()
with open(file, "r") as file2:
     lines_file2 = file2.readlines()
     with open(file1, "w") as f_w:
           for line in lines_file1:
               if line not in lines_file2
                  f_w.write(line)

The downside of this approach is that you are loading the entire files into memory.

user_13668710

You can use set operations to do this with few lines of code.

Read two file and convert the list of lines into the set and use set operations

line_file1 = set(line_file1)
line_file2 = set(line_file2)
result = line_file1 - line_file2

Now write the result set each element (line) to the file.

Note: repeated data in file1 will be also removed.

user_135238100
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