Develop Reference

how to write a line to read a certain sentence in a text file?

I am currently learning how to code python and i need help with something.
is there a way where I can only allow the script to read a line that starts with Text = .. ?
Because I want the program to read the text file and the text file has a lot of other sentences but I only want the program to focus on the sentences that starts with Text = .. and print it out, ignoring the other lines in the text file.
for example,
in text file:
min = 32.421
text = " Hello I am Robin and I am hungry"
max = 233341.42
how I want my output to be:
Hello I am Robin and I am hungry
I want the output to just solely be the sentence so without the " " and text =
This is my code so far after reading through comments!
import os
import sys
import glob
from english_words import english_words_set
try:
print('Finding file...')
file = glob.glob(sys.argv[1])
print("Found " + str(len(file)) + " file!")
print('LOADING NOW...')
with open(file) as f:
lines = f.read()
for line in lines:
if line.startswith('Text = '):
res = line.split('"')[1]
print(res)

You can read the text file and read its lines like so :
# open file
with open('text_file.txt') as f:
# store the list of lines contained in file
lines = f.readlines()
for line in lines:
# find match
if line.startswith('text ='):
# store the string inside double quotes
res = line.split('"')[1]
print(res)
This should print your expected output.

You can open the file and try to find if the word "text" begins a sentence in the file and then checking the value by doing
file = open("file.txt", "r") # specify the variable as reading the file, change file.txt to the files path
for line in file: # for each line in file
if line.startswith("text"): # checks for text following a new line
text = line.strip() # removes any whitespace from the line
text = text.replace("text = \"", "") # removes the part before the string
text = text.replace("\"", "") # removes the part after the string
print(text)
Or you could convert it from text to something like yml or toml (in python 3.11+) as those are natively supported in python and are much simpler than text files while still keeping your file system about the same. It would store it as a dictionary instead of a string in the variable.

List comprehensions in python:
https://www.youtube.com/watch?v=3dt4OGnU5sM
Using list comprehension with files:
https://www.youtube.com/watch?v=QHFWb_6fHOw
First learn list comprehensions, then the idea is this:
listOutput = ['''min = 32.421
text = "Hello I am Robin and I am hungry"
max = 233341.42''']
myText = ''.join(listOutput)
indexFirst= myText.find("text") + 8 # add 8 to this index to discard {text = "}
indexLast = myText.find('''"''', indexFirst) # locate next quote since indexFirst position
print(myText[indexFirst:indexLast])
Output:
Hello I am Robin and I am hungry

with open(file) as f:
lines = f.read().split("\n")
prefix = "text = "
for line in lines:
if line.startswith(prefix):
# replaces the first occurence of prefix and assigns it to result
result = line.replace(prefix, '', 1)
print(result)
Alternatively, you could use result = line.removeprefix(prefix) but removeprefix is only available in python3.9 upwards

Is there any shortcut in Python to remove all blanks at the end of each line in a file?

I've learned that we can easily remove blank lined in a file or remove blanks for each string line, but how about remove all blanks at the end of each line in a file ?
One way should be processing each line for a file, like:
with open(file) as f:
for line in f:
store line.strip()
Is this the only way to complete the task ?

Possibly the ugliest implementation possible but heres what I just scratched up :0
def strip_str(string):
last_ind = 0
split_string = string.split(' ')
for ind, word in enumerate(split_string):
if word == '\n':
return ''.join([split_string[0]] + [ ' {} '.format(x) for x in split_string[1:last_ind]])
last_ind += 1

Don't know if these count as different ways of accomplishing the task. The first is really just a variation on what you have. The second does the whole file at once, rather than line-by-line.
Map that calls the 'rstrip' method on each line of the file.
import operator
with open(filename) as f:
#basically the same as (line.rstrip() for line in f)
for line in map(operator.methodcaller('rstrip'), f)):
# do something with the line
read the whole file and use re.sub():
import re
with open(filename) as f:
text = f.read()
text = re.sub(r"\s+(?=\n)", "", text)

You just want to remove spaces, another solution would be...
line.replace(" ", "")
Good to remove white spaces.

python3.5.2 deleting all matching characters from a file

Given the following exemple how can i remove all "a" characters from a file that have the following content:
asdasdasd \n d1233sss \n aaa \n 123
I wrote the following solution but it does not work:
with open("testfisier","r+") as file:
for line in file:
for index in range(len(line)):
if line[index] is "a":line[index].replace("a","")

There weren't any changes because you didn't write it back to the file.
with open("testfisier", "r+") as file:
for line in file:
for index in range(len(line)):
if line[index] is "a":
replace_file = line[index].replace("a", "")
# Write the changes.
file.write(replace_file)
Or:
with open("testfisier", "r+") as f:
f.write(f.read().replace("a", ""))

Try using regexp substitution. For instance, assuming you have read in the string and named it a_string
import re
re.sub('a','',a_string,'')
This would be one of many possible solutions.
Hope this helps!

You can try this:
import re
data = open("testfisier").read()
final_data = re.sub('a+', '', data)

You can call replace on a long string. No need to call it on single chars. Also, replace does not change a string, but returns a new one:
with open("testfisier", "r+") as file:
text = file.read()
text = text.replace("a", "") # replace a's in the entire text
file.seek(0) # move file pointer back to start
file.write(text)

Remove a specific letter from a specific line in a file in python

This is probably a duplicate, but I couldn't find my answer anywhere.
I have a text file and I want to remove a specific character from a specific line.
Here's one example:
#textfile.txt
Hey!
1234/
How are you//?
9/23r
How can I remove the slash from the second line?
The output should be:
#textfile.txt
Hey!
1234
How are you//?
9/23r
I've got no code and no clue on how to do this.
I run python 2.7.14 on Debian.

You can read the file line by line and identify the line you want to modify. Then identify the index/location of the character you want to modify(remove).
Replace it with blank and write the text line by line into the file.
#opeing the .txt file
fp = open("data.txt", "r")
#reading text line by line
text= fp.readlines()
#searching for character to remove
char = text[1][-2]
#removing the character by replacing it with blank
text[1] = text[1].replace(char, "")
#opeing the file in write mode
fw = open("data.txt", "w")
#writing lines one by one
for lines in text:
fw.write(lines)
#closing the file
fw.close()

A simple solution is to read in the entire file, find the line that you want to change, change it, and write out all of the content again:
filename = 'textfile.txt'
original = '1234/'
replacement = '1234'
# Open file for reading and read all lines into a list
with open('textfile.txt') as f:
lines = f.readlines()
# Find the line number (index) of the original string
index = lines.index(original + '\n')
# Replace this element of the list
lines[index] = replacement + '\n'
# Write out the modified lines to disk
with open(filename, 'w') as f:
f.writelines(lines)

how to replace a line of two words in a file using python

I want to replace a line in a file but my code doesn't do what I want. The code doesn't change that line. It seems that the problem is the space between ALS and 4277 characters in the input.txt. I need to keep that space in the file. How can I fix my code?
A part part of input.txt:
ALS 4277
Related part of the code:
for lines in fileinput.input('input.txt', inplace=True):
print(lines.rstrip().replace("ALS"+str(4277), "KLM" + str(4945)))
Desired output:
KLM 4945

Using the same idea that other user have already pointed out, you could also reproduce the same spacing, by first matching the spacing and saving it in a variable (spacing in my code):
import re
with open('input.txt') as f:
lines = f.read()
match = re.match(r'ALS(\s+)4277', lines)
if match != None:
spacing = match.group(1)
lines = re.sub(r'ALS\s+4277', 'KLM%s4945'%spacing, lines.rstrip())
print lines

As the spaces vary you will need to use regex to account for the spaces.
import re
lines = "ALS 4277 "
line = re.sub(r"(ALS\s+4277)", "KLM 4945", lines.rstrip())
print(line)

Try:
with open('input.txt') as f:
for line in f:
a, b = line.strip().split()
if a == 'ALS' and b == '4277':
line = line.replace(a, 'KLM').replace(b, '4945')
print(line, end='') # as line has '\n'