I am trying to code something where I first look for some string in a line in a txt file and when it is found I want to skip that row and the row below to get a new txt file without those rows. I really didn't get any solution from other questions here so maybe this will work
My code looks like this now:
with open("bla.txt", "r+") as f
new_f = f.readlines()
f.seek(0)
for line in new_f:
if "abc" not in line:
f.write(line)
else:
pass
pass
f.truncate()
I tried it with next(f) aswell but it didn't work for me. thanks in advance
This code creates a new file that skip the current and next row if the current row has the string ABC:
with open('bla.txt','r') as f:
text = f.read()
lines = text.split('\n')
with open('new_file.txt','w') as nf:
l = 0
while l<(len(lines)):
if 'ABC' in lines[l]:
l = l+2
else:
nf.write(lines[l]+'\n')
l = l+1
Try something simple like this:
import os
search_for = 'abc'
with open('input.txt') as f, open('output.txt', 'w') as o:
for line in f:
if search_for in line:
next(f) # we need to skip the next line
# since we are already processing
# the line with the string
# in effect, it skips two lines
else:
o.write(line)
os.rename('output.txt', 'input.txt')
Here is a repl with sample code.
Related
here is what I got txt and open
txt file looks like
f = open('data.txt', 'r')
print(f.read())
the show['Cat\n','Dog\n','Cat\n','Dog\n'........]
output
But I would like to get this
['C\n','D\n','C\n','D\n'........]
First you'll want to open the file in read mode (r flag in open), then you can iterate through the file object with a for loop to read each line one at a time. Lastly, you want to access the first element of each line at index 0 to get the first letter.
first_letters = []
with open('data.txt', 'r') as f:
for line in f:
first_letters.append(line[0])
print(first_letters)
If you want to have the newline character still present in the string you can modify line 5 from above to:
first_letters.append(line[0] + '\n')
f = open("data.txt", "r")
for x in f:
print(x[0])
f.close()
I'm new to python hence I am unable to implement the solutions I've found online in order to fix my problem.
I am trying to add a specific string to the end of a specific line to a textfile. As I understand text commands, I must overwrite the file if I don't want to append to the end of it. So, my solution is as follows:
ans = 'test'
numdef = ['H',2]
f = open(textfile, 'r')
lines = f.readlines()
f.close()
f = open(textfile, 'w')
f.write('')
f.close()
f = open(textfile, 'a')
for line in lines:
if int(line[0]) == numdef[1]:
if str(line[2]) == numdef[0]:
k = ans+ line
f.write(k)
else:
f.write(line)
Basically, I am trying to add variable ans to the end of a specific line, the line which appears in my list numdef. So, for example, for
2 H: 4,0 : Where to search for information : google
I want
2 H: 4,0 : Where to search for information : google test
I have also tried using line.insert() but to no avail.
I understand using the 'a' function of the open command is not so relevant and helpful here, but I am out of ideas. Would love tips with this code, or if maybe I should scrap it and rethink the whole thing.
Thank you for your time and advice!
When you use the method
lines = f.readlines()
Python automatically adds "\n" to the end of each line.
Try instead of :
k = line+ans
The following:
k = line.rstrip('\n') + ans
Good luck!
Try this. You don't have an else case if it meets the first requirement but not the other.
ans = 'test'
numdef = ['H',2]
f = open(textfile, 'r')
lines = f.readlines()
f.close()
f = open(textfile, 'w')
f.write('')
f.close()
f = open(textfile, 'a')
for line in lines:
if int(line[0]) == numdef[1] and str(line[2]) == numdef[0]:
k = line.replace('\n','')+ans
f.write(k)
else:
f.write(line)
f.close()
Better way:
#initialize variables
ans = 'test'
numdef = ['H',2]
#open file in read mode, add lines into lines
with open(textfile, 'r') as f:
lines=f.readlines()
#open file in write mode, override everything
with open(textfile, 'w') as f:
#in the list comprehension, loop through each line in lines, if both of the conditions are true, then take the line, remove all newlines, and add ans. Otherwise, remove all the newlines and don't add anything. Then combine the list into a string with newlines as separators ('\n'.join), and write this string to the file.
f.write('\n'.join([line.replace('\n','')+ans if int(line[0]) == numdef[1] and str(line[2]) == numdef[0] else line.replace('\n','') for line in lines]))
I have a file 'master.sql' that contains:
a.b.c
d.e.f
g.h.i
and I want to write on 'databases.sql' just the first letters, like this:
a
d
g
Here is my code, but returns just the last letter, the 'g'.
with open ('master.sql', 'r') as f:
for line in f:
x=(line.split('.')[0])
with open('databases.sql', 'w') as f:
f.write(str(x))
How can I fix this?
You'll need to write your data as you read it, otherwise you're not going to be able to do what you want. Fortunately, with allows you to open multiple files concurrently. This should work for you.
with open ('master.sql', 'r') as f1, open('databases.sql', 'w') as f2:
for line in f1:
f2.write(line.split('.')[0] + '\n')
Don't forget to write a newline, because file.write doesn't add one automatically.
Using list:
x = []
with open('master.sql', 'r') as f:
for line in f.readlines():
x.append(line.split('.')[0])
with open('databases.sql', 'w') as f:
for word in x:
f.write(str(word)+'\n')
The variable x receives all values, but each loop overwrite the last value. Hence, the result is 'g'.
To save all values you can do like this:
lst = []
with open ('master.sql', 'r') as f:
for line in f:
lst.append(line.split('.')[0])
x = '\n'.join(lst)
with open('databases.sql', 'w') as f:
f.write(x)
I want to open a file, search for a specific word, change the word and save the file again. Sounds really easy - but I just can't get it working... I know that I have to overwrite the whole file but only change this one word!
My Code:
f = open('./myfile', 'r')
linelist = f.readlines()
f.close
for line in linelist:
i =0;
if 'word' in line:
for number in arange(0,1,0.1)):
myNumber = 2 - number
myNumberasString = str(myNumber)
myChangedLine = line.replace('word', myNumberasString)
f2 = open('./myfile', 'w')
f2.write(line)
f2.close
#here I have to do some stuff with these files so there is a reason
#why everything is in this for loop. And I know that it will
#overwrite the file every loop and that is good so. I want that :)
If I make it like this, the 'new' myfile file contains only the changed line. But I want the whole file with the changed line... Can anyone help me?
****EDIT*****
I fixed it! I just turned the loops around and now it works perfectly like this:
f=open('myfile','r')
text = f.readlines()
f.close()
i =0;
for number in arange(0,1,0.1):
fw=open('mynewfile', 'w')
myNumber = 2 - number
myNumberasString = str(myNumber)
for line in text:
if 'word' in line:
line = line.replace('word', myNumberasString)
fw.write(line)
fw.close()
#do my stuff here where I need all these input files
You just need to write out all the other lines as you go. As I said in my comment, I don't know what you are really trying to do with your replace, but here's a slightly simplified version in which we're just replacing all occurrences of 'word' with 'new':
f = open('./myfile', 'r')
linelist = f.readlines()
f.close
# Re-open file here
f2 = open('./myfile', 'w')
for line in linelist:
line = line.replace('word', 'new')
f2.write(line)
f2.close()
Or using contexts:
with open('./myfile', 'r') as f:
lines = f.readlines()
with open('./myfile', 'w') as f:
for line in lines:
line = line.replace('word', 'new')
f.write(line)
Use fileinput passing in whatever you want to replace:
import fileinput
for line in fileinput.input("in.txt",inplace=True):
print(line.replace("whatever","foo"),end="")
You don't seem to be doing anything special in your loop that cannot be calculated first outside the loop, so create the string you want to replace the word with and pass it to replace.
inplace=True will mean the original file is changed. If you want to verify everything looks ok then remove the inplace=True for the first run and you will actually see the replaced output instead of the lines being written to the file.
If you want to write to a temporary file, you can use a NamedTemporaryFile with shutil.move:
from tempfile import NamedTemporaryFile
from shutil import move
with open("in.txt") as f, NamedTemporaryFile(dir=".",delete=False) as out:
for line in f:
out.write(line.replace("whatever","foo"))
move("in.txt",out.name)
One problem you may encounter is matching substrings with replace so if you know the word is always followed in the middle of a sentence surrounded by whitespace you could add that but if not you will need to split and check every word.
from tempfile import NamedTemporaryFile
from shutil import move
from string import punctuation
with open("in.txt") as f, NamedTemporaryFile(dir=".",delete=False) as out:
for line in f:
out.write(" ".join(word if word.strip(punctuation) != "whatever" else "foo"
for word in line.split()))
The are three issues with your current code. First, create the f2 file handle before starting the loop, otherwise you'll overwrite the file in each iteration. Third, you are writing an unmodified line in f2.write(line). I guess you meant f2.write(myChangedLine)? Third, you should add an else statement that writes unmodified lines to the file. So:
f = open('./myfile', 'r')
linelist = f.readlines()
f.close
f2 = open('./myfile', 'w')
for line in linelist:
i =0;
if 'word' in line:
for number in arange(0,1,0.1)):
myNumber = 2 - number
myNumberasString = str(myNumber)
myChangedLine = line.replace('word', myNumberasString)
f2.write(myChangedLine)
else:
f2.write(line)
f2.close()
If I remove [1:], if works fine and prints all data.
f = open("test.csv", "r")
lines = f.readlines()
f.close()
print lines
result:
['title1,title2\raa,aaaa\rbb,bbbb\rcc,cccc']
but if I try to skip the first line by adding [1:]
f = open("test.csv", "r")
lines = f.readlines()[1:]
f.close()
print lines
it prints an empty array
[]
I'm using python 2.7.6.
Does anyone know why?
result:
['title1,title2\raa,aaaa\rbb,bbbb\rcc,cccc']
but if I try to skip the first line by adding [1:] it prints empty array
It looks like you have a platform line encoding issue. You're assuming that python reads this as a multi-line file; however, python only sees one line.
Modify your code to do this...
f = open("test.csv", "r")
lines = f.read().splitlines() # Thanks to Ashwini's comment for tip
f.close()
print lines