When using python via the command line, if I see a mistake on a previous line of a nested statement is there any way to remove or edit that line once it has already been entered?
e.g.:
>>> file = open("file1", "w")
>>> for line in file:
... parts = line.split('|') <-- example, I meant to type '\' instead
... print parts[0:1]
... print ";"
... print parts[1:]
so rather than retyping the entire thing all over to fix one char, can I go back and edit something in hindsight?
I know I could just code it up in vim or something and have a persistent copy I can do anything I want with, but I was hoping for a handy-dandy trick with the command line.
-- thanks!
You can't do such a thing in the original python interpreter, however, if you use the last version of IPython, it provides a lightweight GUI (looks like a simple shell, but is a GUI in fact) which features multi-line editing, syntax highlighting and a bunch of other things. To use IPython GUI, run it with the ipython qtconsole command.
Not that I know of in all the years I've been coding Python. That's what text editors are for =)
If you are an Emacs user, you can set your environment up such that the window is split into the code buffer and Python shell buffer, and then execute your entire buffer to see the changes.
Maybe. The Python Tutorial says:
Perhaps the quickest check to see whether command line editing is supported is typing Control-P to the first Python prompt you get. If it beeps, you have command line editing; see Appendix Interactive Input Editing and History Substitution for an introduction to the keys. If nothing appears to happen, or if ^P is echoed, command line editing isn’t available; you’ll only be able to use backspace to remove characters from the current line.
In addition to #MatToufoutu's suggestion, you might also take a look at DreamPie, though it's just a GUI for the shell without IPython's other extensions.
Now instead of ipython use
jupyter console
in cmd prompt
Related
This question already has an answer here:
Using subprocess.Popen (shell=True) with windows folders
(1 answer)
Closed 2 years ago.
The following code can open the test.txt file with notepad
subprocess.Popen(['start','test.txt'],shell=True)
But this won't open a file with a space in its name like 'the test.txt'.
I've tried using raw string(r'...'), double quote on cmd, '%20' to substitute the space, but none of that works.
Passing a list of arguments with shell=True happens to generally work on Windows, but is really never correct. Of course, start is a shell (cmd) command, so you need a shell here; but then, you also need to quote the string for the shell.
subproces.run('start "the test.txt"', shell=True)
Notice also that I switched to subprocess.run(); you generally want to avoid raw Popen whenever you can, as also suggested in the documentation.
It's much easier to rename the file with an underscore or dash etc.
I had a similar issue once with a client. I'm fairly certain we concluded by renaming by hand all of the necessary files to replace a space with an underscore.
Unless python have released a patch (or indeed, I was oblivious), I think it may be impossible.
Python reads a space and goes "okay, thats that command, what's next?" and then reads whatever follows the space, excluding certain things like string variables.
Take these lines
import os
os.system("start EXCEL.EXE my workbook.xlsb")
Python of course imports the os module here, then in line two it runs the os.system command with the parameters; start, EXCEL.EXE, my, workbook.xlsb
in fact it doesn't, once it reaches the filename "my" without an extension it quits and throws an error in the shell.
I need to extract text from a PDF. I tried the PyPDF2, but the textExtract method returned an encrypted text, even though the pdf is not encrypted acoording to the isEncrypted method.
So I moved on to trying accessing a program that does the job from the command prompt, so I could call it from python with the subprocess module. I found this program called textExtract, which did the job I wanted with the following command line on cmd:
"textextract.exe" "download.pdf" /to "download.txt"
However, when I tried running it with subprocess I couldn't get a 0 return code.
Here is the code I tried:
textextract = shlex.split(r'"textextract.exe" "download.pdf" /to "download.txt"')
subprocess.run(textextract)
I already tried it with shell=True, but it didn't work.
Can anyone help me?
I was able to get the following script to work from the command line after installing the PDF2Text Pilot application you're trying to use:
import shlex
import subprocess
args = shlex.split(r'"textextract.exe" "download.pdf" /to "download.txt"')
print('args:', args)
subprocess.run(args)
Sample screen output of running it from a command line session:
> C:\Python3\python run-textextract.py
args: ['textextract.exe', 'download.pdf', '/to', 'download.txt']
Progress:
Text from "download.pdf" has been successfully extracted...
Text extraction has been completed!
The above output was generated using Python 3.7.0.
I don't know if your use of spyder on anaconda affects things or not since I'm not familiar with it/them. If you continue to have problems with this, then, if it's possible, I suggest you see if you can get things working directly—i.e. running the the Python interpreter on the script manually from the command line similar to what's shown above. If that works, but using spyder doesn't, then you'll at least know the cause of the problem.
There's no need to build a string of quoted strings and then parse that back out to a list of strings. Just create a list and pass that:
command=["textextract.exe", "download.pdf", "/to", "download.txt"]
subprocess.run(command)
All that shlex.split is doing is creating a list by removing all of the quotes you had to add when creating the string in the first place. That's an extra step that provides no value over just creating the list yourself.
I'm using PyCharm, and when I try to execute the statement from here:
!head -n5 {train_dataset_fp}
IDE complains that this is SyntaxError: invalid syntax and program never executes. I thought the entire tutorial on TensorFlow is in Python, but seems like this code from completely different language. Has anyone proceed successfully through the TensorFlow: Get Started tutorial?
This is not a python command, this is a unix one, to launch the head program.
You can use PyCharm to open a Terminal on your target machine, and type:
head -n5 {train_dataset_fp}
... replacing {train_dataset_fp} with the actual path to your dataset, which you obtained/printed in the previous step of the tutorial, c.f. lines:
train_dataset_fp = tf.keras.utils.get_file(fname=os.path.basename(train_dataset_url),
origin=train_dataset_url)
print("Local copy of the dataset file: {}".format(train_dataset_fp))
Since you're on Windows, you need to use Windows commands to achieve what head would do. If you have Powershell installed, you can use the command gc. If you don't, here's a workaround to print the first 5 lines of file.txt, prefixed with the line number:
findstr /n ".*" file.txt | findstr /b "[1-5]:"
inspired by this answer. Basically it numbers all lines in the file and then picks the first five. Obviously pretty inefficient for large files though. Use the "!" prefix as needed.
Is there a way to retrieve the path to the interpreter a UNIX shell would use for a given script? (preferably in a Python API or as shell command)?
To be used like this:
$ get_bang ./myscript.py
/usr/bin/python3
Of course I could extract it manually using RE but I'm sure in real world that's more complicated than just handling the first line and I don't want to re-invent the wheel..
The reason I need this is I want to call the script from inside another script and I want to add parameters to the interpreter.
Actually, it isn't more complicated than reading (the first word) of the first line.
Try putting the shebang on the second line (or even just putting a space before the #) and see what happens.
Also see http://www.in-ulm.de/~mascheck/various/shebang/ and http://homepages.cwi.nl/~aeb/std/hashexclam-1.html for more than you've ever wanted to know about the shebang feature.
Many ways - for example:
sed -n '1s/^#!//p' filename
prints for example
/bin/sh
or (if multiword)
/usr/bin/env perl
or nothing, if here isn't shebang
In the actual window where I right code is there a way to insert part of the code into everyline that I already have. Like insert a comma into all lines at the first spot>?
You need a file editor, not python.
Install the appropriate VIM variant for your operating system
Open the file you want to modify using VIM
Type: :%s/^/,/
Type: :wq
If you are in UNIX environment, open up a terminal, cd to the directory your file is in and use the sed command. I think this may work:
sed "s/\n/\n,/" your_filename.py > new_filename.py
What this says is to replace all \n (newline character) to \n, (newline character + comma character) in your_filename.py and to output the result into new_filename.py.
UPDATE: This is much better:
sed "s/^/,/" your_filename.py > new_filename.py
This is very similar to the previous example, however we use the regular expression token ^ which matches the beginning of each line (and $ is the symbol for end).
There are chances this doesn't work or that it doesn't even apply to you because you didn't really provide that much information in your question (and I would have just commented on it, but I can't because I don't have enough reputation or something). Good luck.
Are you talking about the interactive shell? (a.k.a. opening up a prompt and typing python)? You can't go back and edit what those previous commands did (as they have been executed), but you can hit the up arrow to flip through those commands to edit and reexecute them.
If you're doing anything very long, the best bet is to write your program into your text editor of choice, save that file, then launch it.
Adding a comma to the start of every line with Python:
import sys
src = open(sys.argv[1])
dest = open('withcommas-' + sys.argv[1],'w')
for line in src:
dest.write(',' + line)
src.close()
dest.close()
Call like so: C:\Scripts>python commaz.py cc.py. This is a bizzare thing to do, but who am I to argue.
Code is data. You could do this like you would with any other text file. Open the file, read the line, stick a comma on the front of it, then write it back to file.
Also, most modern IDEs/text editors have the ability to define macros. You could post a question asking for specific help for your editor. For example, in Emacs I would use C-x ( to start defining a macro, then ',' to write a comma, then C-b C-n to go back a character and down a line, then C-x ) to end my macro. I could then run this macro with C-x e, pressing e to execute it an additional time.