I'm trying to get a Python 3 program to do some manipulations with a text file filled with information. However, when trying to read the file I get the following error:
Traceback (most recent call last):
File "SCRIPT LOCATION", line NUMBER, in <module>
text = file.read()
File "C:\Python31\lib\encodings\cp1252.py", line 23, in decode
return codecs.charmap_decode(input,self.errors,decoding_table)[0]
UnicodeDecodeError: 'charmap' codec can't decode byte 0x90 in position 2907500: character maps to `<undefined>`
The file in question is not using the CP1252 encoding. It's using another encoding. Which one you have to figure out yourself. Common ones are Latin-1 and UTF-8. Since 0x90 doesn't actually mean anything in Latin-1, UTF-8 (where 0x90 is a continuation byte) is more likely.
You specify the encoding when you open the file:
file = open(filename, encoding="utf8")
If file = open(filename, encoding="utf-8") doesn't work, try
file = open(filename, errors="ignore"), if you want to remove unneeded characters. (docs)
Alternatively, if you don't need to decode the file, such as uploading the file to a website, use:
open(filename, 'rb')
where r = reading, b = binary
As an extension to #LennartRegebro's answer:
If you can't tell what encoding your file uses and the solution above does not work (it's not utf8) and you found yourself merely guessing - there are online tools that you could use to identify what encoding that is. They aren't perfect but usually work just fine. After you figure out the encoding you should be able to use solution above.
EDIT: (Copied from comment)
A quite popular text editor Sublime Text has a command to display encoding if it has been set...
Go to View -> Show Console (or Ctrl+`)
Type into field at the bottom view.encoding() and hope for the best (I was unable to get anything but Undefined but maybe you will have better luck...)
TLDR: Try: file = open(filename, encoding='cp437')
Why? When one uses:
file = open(filename)
text = file.read()
Python assumes the file uses the same codepage as current environment (cp1252 in case of the opening post) and tries to decode it to its own default UTF-8. If the file contains characters of values not defined in this codepage (like 0x90) we get UnicodeDecodeError. Sometimes we don't know the encoding of the file, sometimes the file's encoding may be unhandled by Python (like e.g. cp790), sometimes the file can contain mixed encodings.
If such characters are unneeded, one may decide to replace them by question marks, with:
file = open(filename, errors='replace')
Another workaround is to use:
file = open(filename, errors='ignore')
The characters are then left intact, but other errors will be masked too.
A very good solution is to specify the encoding, yet not any encoding (like cp1252), but the one which has ALL characters defined (like cp437):
file = open(filename, encoding='cp437')
Codepage 437 is the original DOS encoding. All codes are defined, so there are no errors while reading the file, no errors are masked out, the characters are preserved (not quite left intact but still distinguishable).
Stop wasting your time, just add the following encoding="cp437" and errors='ignore' to your code in both read and write:
open('filename.csv', encoding="cp437", errors='ignore')
open(file_name, 'w', newline='', encoding="cp437", errors='ignore')
Godspeed
for me encoding with utf16 worked
file = open('filename.csv', encoding="utf16")
For those working in Anaconda in Windows, I had the same problem. Notepad++ help me to solve it.
Open the file in Notepad++. In the bottom right it will tell you the current file encoding.
In the top menu, next to "View" locate "Encoding". In "Encoding" go to "character sets" and there with patiente look for the enconding that you need. In my case the encoding "Windows-1252" was found under "Western European"
Before you apply the suggested solution, you can check what is the Unicode character that appeared in your file (and in the error log), in this case 0x90: https://unicodelookup.com/#0x90/1 (or directly at Unicode Consortium site http://www.unicode.org/charts/ by searching 0x0090)
and then consider removing it from the file.
def read_files(file_path):
with open(file_path, encoding='utf8') as f:
text = f.read()
return text
OR (AND)
def read_files(text, file_path):
with open(file_path, 'rb') as f:
f.write(text.encode('utf8', 'ignore'))
In the newer version of Python (starting with 3.7), you can add the interpreter option -Xutf8, which should fix your problem. If you use Pycharm, just got to Run > Edit configurations (in tab Configuration change value in field Interpreter options to -Xutf8).
Or, equivalently, you can just set the environmental variable PYTHONUTF8 to 1.
for me changing the Mysql character encoding the same as my code helped to sort out the solution. photo=open('pic3.png',encoding=latin1)
Let's say i have the following file,
dummy_file.txt(contents below)
first line
third line
how can i add a line to that file right in the middle so the end result is:
first line
second line
third line
I have looked into opening the file with the append option, however that adds the line to the end of the file.
with open("dummy_file.txt", 'r') as file:
lines = file.readlines()
lines.insert(1, "second line\n")
with open("dummy_file.txt", 'w') as output:
output.writelines(lines)
So:
We open the file an read all the lines making a list.
We insert to the list the desired new line, using \n for a new line.
We open the file again but this time to write.
We write all the lines from the list.
But I wouldn't recommend this method, due it hight memory usage (if the file is big).
The standard file methods don't support inserting into the middle of a file. You need to read the file, add your new data to the data that you read in, and then re-write the whole file.
I've tried searching the web, and a number of different things I've read on the web, but don't seem to get the desired result.
I'm using Windows 7 and Python 3.6.
I'm connecting to an Oracle db with cx_oracle and creating a text file with the query results. The file that is created (which I'll call my_file.txt to make it easy) has 3688 lines in it all with CRLF which needs to be converted to the unix LF.
If I run python crlf.py my_file.txt it is all converted correctly & there is no issues, but that means I need to run another command manually which I do not want to do.
So I tried adding the code below to my file.
filename = "NameOfFileToBeConverted"
fileContents = open(filename,"r").read()
f = open(filename,"w", newline="\n")
f.write(fileContents)
f.close()
This does convert the majority of the CRLF to LF but # line 3501 it has a NUL character 3500 times on the one line followed by a row of data from the database & it ends with the CRLF, every line from here on still has the CRLF.
So with that not working, I removed it and then tried
import subprocess
subprocess.Popen("crlf.py "+ filename, shell=True)
I also tried using
import os
os.system("crlf.py "+ filename)
The "+ filename" in the two examples above is just providing the filename that is created during the data extract.
I don't know what else to try from here.
Convert Line Endings in-place (with Python 3)
Windows to Linux/Unix
Here is a short script for directly converting Windows line endings (\r\n also called CRLF) to Linux/Unix line endings (\n also called LF) in-place (without creating an extra output file):
# replacement strings
WINDOWS_LINE_ENDING = b'\r\n'
UNIX_LINE_ENDING = b'\n'
# relative or absolute file path, e.g.:
file_path = r"c:\Users\Username\Desktop\file.txt"
with open(file_path, 'rb') as open_file:
content = open_file.read()
content = content.replace(WINDOWS_LINE_ENDING, UNIX_LINE_ENDING)
with open(file_path, 'wb') as open_file:
open_file.write(content)
Linux/Unix to Windows
Just swap the line endings to content.replace(UNIX_LINE_ENDING, WINDOWS_LINE_ENDING).
Code Explanation
Important: Binary Mode We need to make sure that we open the file both times in binary mode (mode='rb' and mode='wb') for the conversion to work.
When opening files in text mode (mode='r' or mode='w' without b), the platform's native line endings (\r\n on Windows and \r on old Mac OS versions) are automatically converted to Python's Unix-style line endings: \n. So the call to content.replace() couldn't find any line endings to replace.
In binary mode, no such conversion is done.
Binary Strings In Python 3, if not declared otherwise, strings are stored as Unicode (UTF-8). But we open our files in binary mode - therefore we need to add b in front of our replacement strings to tell Python to handle those strings as binary, too.
Raw Strings On Windows the path separator is a backslash \ which we would need to escape in a normal Python string with \\. By adding r in front of the string we create a so called raw string which doesn't need any escaping. So you can directly copy/paste the path from Windows Explorer.
Alternative We open the file twice to avoid the need of repositioning the file pointer. We also could have opened the file once with mode='rb+' but then we would have needed to move the pointer back to start after reading its content (open_file.seek(0)) and truncate its original content before writing the new one (open_file.truncate(0)).
Simply opening the file again in write mode does that automatically for us.
Cheers and happy programming,
winklerrr
Google doesn't give any great results for getting the last line of a file in groovy so I feel this question is necessary.
How does one get the last line of a file in groovy?
Get all lines, then get the last one:
def lines=new File("/home/user/somefile.txt").readLines()
def lastline=lines.get(lines.size()-1)
Or, if the file is dangerously large:
def last=new File('/home/user/somefile.txt').withReader { r-> r.eachLine {it} }
which is almost identical to asker's answer.
Here's what I ended up with:
new File("/home/user/somefile.txt").eachLine {
lastLine = it
}
.eachLine iterates through each line of the text file and lastLine is set to the current iteration until eachLine finishes going through the file. Pretty straightforward.
How does one get the last line of a file in groovy?
It depends on what you know about the file. If the lines in the file are fixed length then you could look at the file size, divide it by the length of each line and then use random file access to jump to the last line in the file and read it. That would be more efficient than reading the entire file. If you don't know the length of the lines then you are probably going to have to read the entire file and discard everything before the last line you read.
I have a text file with special characters as well as normal characters. I am trying to read this file line by line. I have used
string[] lines = System.IO.File.ReadAllLines("Trial.txt");
To read it.
I used a break point and tried to find out the values stored in those lines. It broke some of the lines in between without finishing reading it and stored the rest in a new next line. When I checked the records, I found that the breaking occurs only at the point where there are special characters even though it doesn't happen with a particular special character. If the file has a total of 10 lines and if there is 1 line which has this problem, it reads a total of 11 lines. Can any of you guys pleas help me out with this? The text file is in UTF-8 format.
The File.ReadAllLines method splits the file on carriage return ('\r'), new line ('\n'), or a carriage return followed by a new line (taken from here: http://msdn.microsoft.com/en-us/library/s2tte0y1.aspx).
Check if the line that is not supposed to be split has either of those characters (judging from your reply to Luke Wyatt you probably have a new line ('\n') on that line at the point where it splits).