How to delete lines between two words from text file?

[scharnisto]

Hi,

i need a script, that deletes all the lines between two certain words in a text file. the two words appear several times in the text file.

i have a code, that works so far. the problem is, once it looped for the first time through the text file, the end_word appears before the new start_word. so i have to tell the program, to start searching for the end_word, after the start_word.

here is the code. i hope that makes it more understandable:

orig_file = open ("*Strata1CombinedAll.txt", "r")
lines = orig_file.readlines()




import fnmatch
def find(seq, pattern):
    pattern = pattern.lower()
    for i, n in enumerate(seq):
        if fnmatch.fnmatch(n.lower(), pattern):
            return i
            return -1

def index(seq, pattern):
    result = find(seq, pattern)
    if result == -1:
        raise ValueError
    return result



try:
    for item in lines:
        begin_line = index(lines, "*start_word*")
        end_line = index(lines, "*end_word*") 
        del lines[begin_line:end_line]

except:
    new_text_file = open ("*test604", "w")
    new_text_file.writelines(lines)
    new_text_file.close()

[dwblas]

In the function index(), result will never equal negative one. Also, under the try block you delete records from the same list that the for loop is using leading to errors. To illustrate, look at the length of the list originally and compare to how many records actually print (you should copy the records you want to keep to a new list instead of deleting from the original list).

test_data = [["abc"], ["def"], ["ghi"], ["abc"], ["xyz"], ["abc"], ["mno"], ["rst"]]
ctr = 0
for rec in test_data:
    ctr += 1
    print ctr, rec
    if ctr%2:
        del test_data[ctr]

[dwblas]

Remove all records between "abc" and "def". There should be a way to do this using groupby from itertools but I don't have time now to try it. Perhaps someone else will post it.

test_data = ["abc", "def", "ghi", "xabcy", "xyz", "def", "mno", "rst"]

start = False
saved_list = []

for rec in test_data:
    if "abc" in rec.lower():
        start = True
    if not start:
        saved_list.append(rec)
        ## or in your case
        ##output_file.write(rec)
    if "def" in rec:
        start = False
print saved_list

[scharnisto]

the last code would work. thank you dwblas!
i have it like this now:

orig_file = open (input(), "r")
lines = orig_file.readlines()

start = False
saved_list = []
for rec in lines:
    if "count" in rec:
        start = True
    if not start:
        saved_list.append(rec)
    if "Volume" in rec:
        start= False


new_text_file = open (input(), "w")
new_text_file.writelines(saved_list)
new_text_file.close()

the only problem that is left is, that the last line shall not be deleted. the last line always has the word 'volume' in there. the line before the word 'volume' is always a blank line, which shall be deleted.
any ideas how to get this to work?

[scharnisto]

i figured it out. the following code, does what i need to do.

orig_file = open (input(), "r")
lines = orig_file.readlines()
 
start = False
saved_list = []
for rec in lines:
    if "count" in rec:
        start = True
    if "Volume" in rec:
        start= False
    if not start:
        saved_list.append(rec) 
 
new_text_file = open (input(), "w")
new_text_file.writelines(saved_list)
new_text_file.close()