I am trying to remove duplicate lines from a text file and keep facing issues... The output file keeps putting the first two accounts on the same line. Each account should have a different line... Does anyone know why this is happening and how to fix it?
with open('accounts.txt', 'r') as f:
unique_lines = set(f.readlines())
with open('accounts_No_Dup.txt', 'w') as f:
f.writelines(unique_lines)
accounts.txt:
#account1
#account2
#account3
#account4
#account5
#account6
#account7
#account5
#account8
#account4
accounts_No_Dup.txt:
#account4#account3
#account4
#account8
#account5
#account7
#account1
#account2
#account6
print(unique_lines)
{'#account4', '#account7\n', '#account3\n', '#account6\n', '#account5\n', '#account8\n', '#account4\n', '#account2\n', '#account1\n'}
The last line in your file is missing a newline (technically a violation of POSIX standards for text files, but so common you have to account for it), so "#account4\n" earlier on is interpreted as unique relative to "#account4" at the end. I'd suggest unconditionally stripping newlines, and adding them back when writing:
with open('accounts.txt', 'r') as f:
unique_lines = {line.rstrip("\r\n") for line in f} # Remove newlines for consistent deduplication
with open('accounts_No_Dup.txt', 'w') as f:
f.writelines(f'{line}\n' for line in unique_lines) # Add newlines back
By the by, on modern Python (CPython/PyPy 3.6+, 3.7+ for any interpreter), you can preserve order of first appearance by using a dict rather than a set. Just change the read from the file to:
unique_lines = {line.rstrip("\r\n"): None for line in f}
and you'll see each line the first time it appears, in that order, with subsequent duplicates being ignored.
Your problem is that set changes the order of your lines and your last element doesn't end with \n as you don't have an empty line at the end of your file.
Just add the separator or don't use set.
with open('accounts.txt', 'r') as f:
unique_lines = set()
for line in f.readlines():
if not line.endswith('\n'):
line += '\n'
unique_lines.add(line)
with open('accounts_No_Dup.txt', 'w') as f:
f.writelines(unique_lines)
You can easily do it using unique keyword
The code is as below
import pandas as pd
data = pd.read_csv('d:\\test.txt', sep="/n", header=None)
df = pd.DataFrame(data[0].unique())
with open('d:\\testnew.txt', 'a') as f:
f.write(df.to_string(header = False, index = False)))
Results: Test file to read has data
The result is it removed the duplicate lines
Related
Let's say I have a text file full of nicknames. How can I delete a specific nickname from this file, using Python?
First, open the file and get all your lines from the file. Then reopen the file in write mode and write your lines back, except for the line you want to delete:
with open("yourfile.txt", "r") as f:
lines = f.readlines()
with open("yourfile.txt", "w") as f:
for line in lines:
if line.strip("\n") != "nickname_to_delete":
f.write(line)
You need to strip("\n") the newline character in the comparison because if your file doesn't end with a newline character the very last line won't either.
Solution to this problem with only a single open:
with open("target.txt", "r+") as f:
d = f.readlines()
f.seek(0)
for i in d:
if i != "line you want to remove...":
f.write(i)
f.truncate()
This solution opens the file in r/w mode ("r+") and makes use of seek to reset the f-pointer then truncate to remove everything after the last write.
The best and fastest option, rather than storing everything in a list and re-opening the file to write it, is in my opinion to re-write the file elsewhere.
with open("yourfile.txt", "r") as file_input:
with open("newfile.txt", "w") as output:
for line in file_input:
if line.strip("\n") != "nickname_to_delete":
output.write(line)
That's it! In one loop and one only you can do the same thing. It will be much faster.
This is a "fork" from #Lother's answer (which I believe that should be considered the right answer).
For a file like this:
$ cat file.txt
1: october rust
2: november rain
3: december snow
This fork from Lother's solution works fine:
#!/usr/bin/python3.4
with open("file.txt","r+") as f:
new_f = f.readlines()
f.seek(0)
for line in new_f:
if "snow" not in line:
f.write(line)
f.truncate()
Improvements:
with open, which discard the usage of f.close()
more clearer if/else for evaluating if string is not present in the current line
The issue with reading lines in first pass and making changes (deleting specific lines) in the second pass is that if you file sizes are huge, you will run out of RAM. Instead, a better approach is to read lines, one by one, and write them into a separate file, eliminating the ones you don't need. I have run this approach with files as big as 12-50 GB, and the RAM usage remains almost constant. Only CPU cycles show processing in progress.
I liked the fileinput approach as explained in this answer:
Deleting a line from a text file (python)
Say for example I have a file which has empty lines in it and I want to remove empty lines, here's how I solved it:
import fileinput
import sys
for line_number, line in enumerate(fileinput.input('file1.txt', inplace=1)):
if len(line) > 1:
sys.stdout.write(line)
Note: The empty lines in my case had length 1
If you use Linux, you can try the following approach.
Suppose you have a text file named animal.txt:
$ cat animal.txt
dog
pig
cat
monkey
elephant
Delete the first line:
>>> import subprocess
>>> subprocess.call(['sed','-i','/.*dog.*/d','animal.txt'])
then
$ cat animal.txt
pig
cat
monkey
elephant
Probably, you already got a correct answer, but here is mine.
Instead of using a list to collect unfiltered data (what readlines() method does), I use two files. One is for hold a main data, and the second is for filtering the data when you delete a specific string. Here is a code:
main_file = open('data_base.txt').read() # your main dataBase file
filter_file = open('filter_base.txt', 'w')
filter_file.write(main_file)
filter_file.close()
main_file = open('data_base.txt', 'w')
for line in open('filter_base'):
if 'your data to delete' not in line: # remove a specific string
main_file.write(line) # put all strings back to your db except deleted
else: pass
main_file.close()
Hope you will find this useful! :)
I think if you read the file into a list, then do the you can iterate over the list to look for the nickname you want to get rid of. You can do it much efficiently without creating additional files, but you'll have to write the result back to the source file.
Here's how I might do this:
import, os, csv # and other imports you need
nicknames_to_delete = ['Nick', 'Stephen', 'Mark']
I'm assuming nicknames.csv contains data like:
Nick
Maria
James
Chris
Mario
Stephen
Isabella
Ahmed
Julia
Mark
...
Then load the file into the list:
nicknames = None
with open("nicknames.csv") as sourceFile:
nicknames = sourceFile.read().splitlines()
Next, iterate over to list to match your inputs to delete:
for nick in nicknames_to_delete:
try:
if nick in nicknames:
nicknames.pop(nicknames.index(nick))
else:
print(nick + " is not found in the file")
except ValueError:
pass
Lastly, write the result back to file:
with open("nicknames.csv", "a") as nicknamesFile:
nicknamesFile.seek(0)
nicknamesFile.truncate()
nicknamesWriter = csv.writer(nicknamesFile)
for name in nicknames:
nicknamesWriter.writeRow([str(name)])
nicknamesFile.close()
In general, you can't; you have to write the whole file again (at least from the point of change to the end).
In some specific cases you can do better than this -
if all your data elements are the same length and in no specific order, and you know the offset of the one you want to get rid of, you could copy the last item over the one to be deleted and truncate the file before the last item;
or you could just overwrite the data chunk with a 'this is bad data, skip it' value or keep a 'this item has been deleted' flag in your saved data elements such that you can mark it deleted without otherwise modifying the file.
This is probably overkill for short documents (anything under 100 KB?).
I like this method using fileinput and the 'inplace' method:
import fileinput
for line in fileinput.input(fname, inplace =1):
line = line.strip()
if not 'UnwantedWord' in line:
print(line)
It's a little less wordy than the other answers and is fast enough for
Save the file lines in a list, then remove of the list the line you want to delete and write the remain lines to a new file
with open("file_name.txt", "r") as f:
lines = f.readlines()
lines.remove("Line you want to delete\n")
with open("new_file.txt", "w") as new_f:
for line in lines:
new_f.write(line)
here's some other method to remove a/some line(s) from a file:
src_file = zzzz.txt
f = open(src_file, "r")
contents = f.readlines()
f.close()
contents.pop(idx) # remove the line item from list, by line number, starts from 0
f = open(src_file, "w")
contents = "".join(contents)
f.write(contents)
f.close()
You can use the re library
Assuming that you are able to load your full txt-file. You then define a list of unwanted nicknames and then substitute them with an empty string "".
# Delete unwanted characters
import re
# Read, then decode for py2 compat.
path_to_file = 'data/nicknames.txt'
text = open(path_to_file, 'rb').read().decode(encoding='utf-8')
# Define unwanted nicknames and substitute them
unwanted_nickname_list = ['SourDough']
text = re.sub("|".join(unwanted_nickname_list), "", text)
Do you want to remove a specific line from file so use this snippet short and simple code you can easily remove any line with sentence or prefix(Symbol).
with open("file_name.txt", "r") as f:
lines = f.readlines()
with open("new_file.txt", "w") as new_f:
for line in lines:
if not line.startswith("write any sentence or symbol to remove line"):
new_f.write(line)
To delete a specific line of a file by its line number:
Replace variables filename and line_to_delete with the name of your file and the line number you want to delete.
filename = 'foo.txt'
line_to_delete = 3
initial_line = 1
file_lines = {}
with open(filename) as f:
content = f.readlines()
for line in content:
file_lines[initial_line] = line.strip()
initial_line += 1
f = open(filename, "w")
for line_number, line_content in file_lines.items():
if line_number != line_to_delete:
f.write('{}\n'.format(line_content))
f.close()
print('Deleted line: {}'.format(line_to_delete))
Example output:
Deleted line: 3
Take the contents of the file, split it by newline into a tuple. Then, access your tuple's line number, join your result tuple, and overwrite to the file.
Let's say I have a text file full of nicknames. How can I delete a specific nickname from this file, using Python?
First, open the file and get all your lines from the file. Then reopen the file in write mode and write your lines back, except for the line you want to delete:
with open("yourfile.txt", "r") as f:
lines = f.readlines()
with open("yourfile.txt", "w") as f:
for line in lines:
if line.strip("\n") != "nickname_to_delete":
f.write(line)
You need to strip("\n") the newline character in the comparison because if your file doesn't end with a newline character the very last line won't either.
Solution to this problem with only a single open:
with open("target.txt", "r+") as f:
d = f.readlines()
f.seek(0)
for i in d:
if i != "line you want to remove...":
f.write(i)
f.truncate()
This solution opens the file in r/w mode ("r+") and makes use of seek to reset the f-pointer then truncate to remove everything after the last write.
The best and fastest option, rather than storing everything in a list and re-opening the file to write it, is in my opinion to re-write the file elsewhere.
with open("yourfile.txt", "r") as file_input:
with open("newfile.txt", "w") as output:
for line in file_input:
if line.strip("\n") != "nickname_to_delete":
output.write(line)
That's it! In one loop and one only you can do the same thing. It will be much faster.
This is a "fork" from #Lother's answer (which I believe that should be considered the right answer).
For a file like this:
$ cat file.txt
1: october rust
2: november rain
3: december snow
This fork from Lother's solution works fine:
#!/usr/bin/python3.4
with open("file.txt","r+") as f:
new_f = f.readlines()
f.seek(0)
for line in new_f:
if "snow" not in line:
f.write(line)
f.truncate()
Improvements:
with open, which discard the usage of f.close()
more clearer if/else for evaluating if string is not present in the current line
The issue with reading lines in first pass and making changes (deleting specific lines) in the second pass is that if you file sizes are huge, you will run out of RAM. Instead, a better approach is to read lines, one by one, and write them into a separate file, eliminating the ones you don't need. I have run this approach with files as big as 12-50 GB, and the RAM usage remains almost constant. Only CPU cycles show processing in progress.
I liked the fileinput approach as explained in this answer:
Deleting a line from a text file (python)
Say for example I have a file which has empty lines in it and I want to remove empty lines, here's how I solved it:
import fileinput
import sys
for line_number, line in enumerate(fileinput.input('file1.txt', inplace=1)):
if len(line) > 1:
sys.stdout.write(line)
Note: The empty lines in my case had length 1
If you use Linux, you can try the following approach.
Suppose you have a text file named animal.txt:
$ cat animal.txt
dog
pig
cat
monkey
elephant
Delete the first line:
>>> import subprocess
>>> subprocess.call(['sed','-i','/.*dog.*/d','animal.txt'])
then
$ cat animal.txt
pig
cat
monkey
elephant
Probably, you already got a correct answer, but here is mine.
Instead of using a list to collect unfiltered data (what readlines() method does), I use two files. One is for hold a main data, and the second is for filtering the data when you delete a specific string. Here is a code:
main_file = open('data_base.txt').read() # your main dataBase file
filter_file = open('filter_base.txt', 'w')
filter_file.write(main_file)
filter_file.close()
main_file = open('data_base.txt', 'w')
for line in open('filter_base'):
if 'your data to delete' not in line: # remove a specific string
main_file.write(line) # put all strings back to your db except deleted
else: pass
main_file.close()
Hope you will find this useful! :)
I think if you read the file into a list, then do the you can iterate over the list to look for the nickname you want to get rid of. You can do it much efficiently without creating additional files, but you'll have to write the result back to the source file.
Here's how I might do this:
import, os, csv # and other imports you need
nicknames_to_delete = ['Nick', 'Stephen', 'Mark']
I'm assuming nicknames.csv contains data like:
Nick
Maria
James
Chris
Mario
Stephen
Isabella
Ahmed
Julia
Mark
...
Then load the file into the list:
nicknames = None
with open("nicknames.csv") as sourceFile:
nicknames = sourceFile.read().splitlines()
Next, iterate over to list to match your inputs to delete:
for nick in nicknames_to_delete:
try:
if nick in nicknames:
nicknames.pop(nicknames.index(nick))
else:
print(nick + " is not found in the file")
except ValueError:
pass
Lastly, write the result back to file:
with open("nicknames.csv", "a") as nicknamesFile:
nicknamesFile.seek(0)
nicknamesFile.truncate()
nicknamesWriter = csv.writer(nicknamesFile)
for name in nicknames:
nicknamesWriter.writeRow([str(name)])
nicknamesFile.close()
In general, you can't; you have to write the whole file again (at least from the point of change to the end).
In some specific cases you can do better than this -
if all your data elements are the same length and in no specific order, and you know the offset of the one you want to get rid of, you could copy the last item over the one to be deleted and truncate the file before the last item;
or you could just overwrite the data chunk with a 'this is bad data, skip it' value or keep a 'this item has been deleted' flag in your saved data elements such that you can mark it deleted without otherwise modifying the file.
This is probably overkill for short documents (anything under 100 KB?).
I like this method using fileinput and the 'inplace' method:
import fileinput
for line in fileinput.input(fname, inplace =1):
line = line.strip()
if not 'UnwantedWord' in line:
print(line)
It's a little less wordy than the other answers and is fast enough for
Save the file lines in a list, then remove of the list the line you want to delete and write the remain lines to a new file
with open("file_name.txt", "r") as f:
lines = f.readlines()
lines.remove("Line you want to delete\n")
with open("new_file.txt", "w") as new_f:
for line in lines:
new_f.write(line)
here's some other method to remove a/some line(s) from a file:
src_file = zzzz.txt
f = open(src_file, "r")
contents = f.readlines()
f.close()
contents.pop(idx) # remove the line item from list, by line number, starts from 0
f = open(src_file, "w")
contents = "".join(contents)
f.write(contents)
f.close()
You can use the re library
Assuming that you are able to load your full txt-file. You then define a list of unwanted nicknames and then substitute them with an empty string "".
# Delete unwanted characters
import re
# Read, then decode for py2 compat.
path_to_file = 'data/nicknames.txt'
text = open(path_to_file, 'rb').read().decode(encoding='utf-8')
# Define unwanted nicknames and substitute them
unwanted_nickname_list = ['SourDough']
text = re.sub("|".join(unwanted_nickname_list), "", text)
Do you want to remove a specific line from file so use this snippet short and simple code you can easily remove any line with sentence or prefix(Symbol).
with open("file_name.txt", "r") as f:
lines = f.readlines()
with open("new_file.txt", "w") as new_f:
for line in lines:
if not line.startswith("write any sentence or symbol to remove line"):
new_f.write(line)
To delete a specific line of a file by its line number:
Replace variables filename and line_to_delete with the name of your file and the line number you want to delete.
filename = 'foo.txt'
line_to_delete = 3
initial_line = 1
file_lines = {}
with open(filename) as f:
content = f.readlines()
for line in content:
file_lines[initial_line] = line.strip()
initial_line += 1
f = open(filename, "w")
for line_number, line_content in file_lines.items():
if line_number != line_to_delete:
f.write('{}\n'.format(line_content))
f.close()
print('Deleted line: {}'.format(line_to_delete))
Example output:
Deleted line: 3
Take the contents of the file, split it by newline into a tuple. Then, access your tuple's line number, join your result tuple, and overwrite to the file.
I'm trying to write to a CSV file with output that looks like this:
14897,40.50891,-81.03926,168.19999
but the CSV writer keeps writing the output with quotes at beginning and end
'14897,40.50891,-81.03926,168.19999'
When I print the line normally, the output is correct but I need to do line.split() or else the csv writer puts output as 1,4,8,9,7 etc...
But when I do line.split() the output is then
['14897,40.50891,-81.03926,168.19999']
Which is written as '14897,40.50891,-81.03926,168.19999'
How do I make the quotes go away? I already tried csv.QUOTE_NONE but doesn't work.
with open(results_csv, 'wb') as out_file:
writer = csv.writer(out_file, delimiter=',')
writer.writerow(["time", "lat", "lon", "alt"])
for f in file_directory):
for line in open(f):
print line
line = line.split()
writer.writerow(line)
with line.split(), you're not splitting according to commas but to blanks (spaces, linefeeds, tabs). Since there are none, you end up with only 1 item per row.
Since this item contains commas, csv module has to quote to make the difference with the actual separator (which is also comma). You would need line.strip().split(",") for it to work, but...
using csv to read your data would be a better idea to fix this:
replace that:
for line in open(some_file):
print line
line = line.split()
writer.writerow(line)
by:
with open(some_file) as f:
cr = csv.reader(f) # default separator is comma already
writer.writerows(cr)
You don't need to read the file manually. You can simply use csv reader.
Replace the inner for loop with:
# with ensures that the file handle is closed, after the execution of the code inside the block
with open(some_file) as file:
row = csv.reader(file) # read rows
writer.writerows(row) # write multiple rows at once
I am reading a file and getting the first element from each start of the line, and comparing it to my list, if found, then I append it to the new output file that is supposed to be exactly like the input file in terms of the structure.
my_id_list = [
4985439
5605471
6144703
]
input file:
4985439 16:0.0719814
5303698 6:0.09407 19:0.132581
5605471 5:0.0486076
5808678 8:0.130536
6144703 5:0.193785 19:0.0492507
6368619 3:0.242678 6:0.041733
my attempt:
output_file = []
input_file = open('input_file', 'r')
for line in input_file:
my_line = np.array(line.split())
id = str(my_line[0])
if id in my_id_list:
output_file.append(line)
np.savetxt("output_file", output_file, fmt='%s')
Question is:
It is currently adding an extra empty line after each line written to the output file. How can I fix it? or is there any other way to do it more efficiently?
update:
output file should be for this example:
4985439 16:0.0719814
5605471 5:0.0486076
6144703 5:0.193785 19:0.0492507
try something like this
# read lines and strip trailing newline characters
with open('input_file','r') as f:
input_lines = [line.strip() for line in f.readlines()]
# collect all the lines that match your id list
output_file = [line for line in input_lines if line.split()[0] in my_id_list]
# write to output file
with open('output_file','w') as f:
f.write('\n'.join(output_file))
I don't know what numpy does to the text when reading it, but this is how you could do it without numpy:
my_id_list = {4985439, 5605471, 6144703} # a set is faster for membership testing
with open('input_file') as input_file:
# Your problem is most likely related to line-endings, so here
# we read the inputfile into an list of lines with intact line endings.
# To preserve the input, exactly, you would need to open the files
# in binary mode ('rb' for the input file, and 'wb' for the output
# file below).
lines = input_file.read().splitlines(keepends=True)
with open('output_file', 'w') as output_file:
for line in lines:
first_word = line.split()[0]
if first_word in my_id_list:
output_file.write(line)
getting the first word of each line is wasteful, since this:
first_word = line.split()[0]
creates a list of all "words" in the line when we just need the first one.
If you know that the columns are separated by spaces you can make it more efficient by only splitting on the first space:
first_word = line.split(' ', 1)[0]
Code snippet below compares two csv files and merge them. My problem is that the second file is printed in new lines.
import csv
import dateutil.parser
with open('a.csv', 'r') as f1:
feed = f1.readlines()
with open ('b.csv', 'r') as f2:
for line in f2.readlines()[1:]:
line = line.split(',')
ts = dateutil.parser.parse(line[3])
print(ts)
for i, log in enumerate(feed):
ls = log.split(',')
ts_start = dateutil.parser.parse(ls[0])
ts_end = dateutil.parser.parse(ls[1])
if (ts >= ts_start) and (ts < ts_end):
print(ts, ts_start, ts_end)
name, tags, mean = line[0], ','.join(line[1:3]),line[-1]
feed[i] = ','.join([log, name, tags, mean])
with open('c.csv', 'w') as f:
f.writelines(feed)
file a:
2015-11-04T13:35:18.657Z,2015-11-04T13:47:06.588Z,load,INSERT
2015-11-04T13:47:47.164Z,2015-11-04T14:07:13.230Z,run,READUPDATE
file b:
name,tags,time,mean
memory_value,"type=memory,instance=buffered",2015-11-04T13:35:00Z,
memory_value,"type=memory,instance=buffered",2015-11-04T13:45:00Z,1.32
memory_value,"type=memory,instance=buffered",2015-11-04T14:05:00Z,1.11
Output:
A1,A2,A3,A4,
A5
B1,B2,B3,B4,
B5,
Expected output:
A1,A2,A3,A4,A5
B1,B2,B3,B4,B5
How can I acheive this?
Thanks
The strings in the list returned by readlines include the newline character at the end of each line, so these may inadvertently be included as you do string manipulation on that data. In particular, ','.join([log, name, tags, mean]) will have a newline between log and name, because log ultimately came from f1.readlines().
Try stripping the newlines from each line before doing anything with it.
for i, log in enumerate(feed):
log = log.strip()
ls = log.split(',')
It may also be necessary to do line = line.strip().split(',') at the top of the first for loop instead of just line = line.split(','). The output looks OK on my machine without it, but I'm not 100% sure that it exactly matches your desired output.
Depending on what version of python you are using you may need to change the 'r' and 'w' to 'rb' and 'wb' in order to read and write files in binary mode. This should help with the new lines.