Can anyone help me with forming programme code which check matching word and delete that line that didn't have matching word

Question

in a text file

Answer 1

path = "sample.txt"
word = "my word"

Open file and copy the lines
lines = []
with open(path, "r") as f:
lines += f.readlines()

delete all the lines that doesn't have the matching word
lines = list(filter(lambda line: word not in line, lines))

#Use the filterd list as you want
print(lines)

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or you can use a for loop instead of the filter function

for i in range(len(lines)):
if word not in lines[i]:
lines.remove(i)

Answer 2

Something like this?

for line in lines:
line = line if word in line else ""