如何用python修改的行替换包含某些字符串的行？

Question

My input is:

*PART, NAME=Part-Default
**
****************************** N O D E S *********************************
*NODE, NSET=ALLNODES
   1,    2.228570e-02,   -8.715290e-01
   2,    1.463382e-02,   -9.181792e-01
*INSTANCE, NAME=Part-Default_1, PART=Part-Default
*END INSTANCE

I want to replace all the fields with Part-Default or Part-Default_1 with Part-1.

Output should be:

*PART, NAME=Part-1
**
****************************** N O D E S *********************************
*NODE, NSET=ALLNODES
   1,    2.228570e-02,   -8.715290e-01
   2,    1.463382e-02,   -9.181792e-01
*INSTANCE, NAME=Part-1, PART=Part-1
*END INSTANCE

What I propose:

lines = f.readlines()
i=0
while (i<len(lines)):
    temp=lines[i].strip().split(',')
    if (temp[1]=="NAME=Part-Default"):
        f.write(""temp"\n")
        temp[1]="NAME=Part-1"
    if (temp[1]=="NAME=Part-1_1"):
        temp[1]="NAME=Part-1"
        f.write(""temp"\n")
    if (temp[2]=="NAME=Part-Default"):
        temp[1]="NAME=Part-1"
        f.write(""temp"\n")
    else
        f.write(""temp"\n")

I am not sure about the writing commands. May be we can directly replace the strings somehow. regards

Answer 1

You can run a regular expression replacement on the whole file. You won't need to do this line-by-line unless you are dealing with truly huge files.

import re

filename = "xxx.txt"
with open(filename, "r") as f:
    content = f.read()
new_content = re.sub(r"(\w+)=Part-(1(_1)?|Default(_1)?)", r"\1=Part-1", content)
with open(filename, "w") as f:
    f.write(new_content)

Answer 2

lines = f.readlines()
for line in lines:
    line.replace("Part-Default_1", "Part-1").replace("Part-Default", "Part-1")

That will replace ANY instance of Part-Default_1. If you want to be more specific then you can use something like:

lines = f.readlines()
for line in lines:
    if line.find("$QUALIFIER"):
        line.replace("Part-Default_1", "Part-1").replace("Part-Default", "Part-1")

Make sure you change $QUALIFER to be something that will qualify which lines you want the replace done on.