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Python terminal input arrow keys and move cursor accordingly

I'm trying to make a simple python program that is meant to be run from a gnome-terminal.
I have an "#" character on screen that I want to move left (when left arrow pressed) and right (when right arrow pressed). How can I do this without using the curses library?

You will have a hard time doing that without using a library such us curses, and I discourage you to do so since you would have to deal with several pitfalls.
That said, you are facing two issues: detecting key presses and printing over the same line several times.
If you do some research you would find that in linux you can read from the standard input disabling the buffering using tty and termios (see here for example). You may use that to detect the pressing of an arrow key.
About printing on the same line, you have some special control character such as the carriage return \r which you may use to achieve your goal.
Putting everything together, the most basic program to move a "#" using the arrow keys would look like this:
#!/usr/bin/env python3
import sys
import termios
import tty
K_RIGHT = b'\x1b[C'
K_LEFT = b'\x1b[D'
def read_keys():
stdin = sys.stdin.fileno()
tattr = termios.tcgetattr(stdin)
try:
tty.setcbreak(stdin, termios.TCSANOW)
while True:
yield sys.stdin.buffer.read1()
except KeyboardInterrupt:
yield None
finally:
termios.tcsetattr(stdin, termios.TCSANOW, tattr)
def reset_line():
print(
'\033[F' + # move up
'\033[K', # clear row
end=''
)
def print_sprite(x):
print((' '*x) + '#')
if __name__ == '__main__':
print('Press Ctrl+c to quit')
sprite_x = 0
print_sprite(sprite_x)
for k in read_keys():
if k == K_LEFT:
sprite_x -= 1
if k == K_RIGHT:
sprite_x += 1
reset_line()
print_sprite(sprite_x)
As you can see this is far away from being a "simple program" and the curses library is definitely the way to go.

Single key detection to work with the possibility of adding long inputs

I have been facing this problem for the last week,I thought it would be trivial but after trying many different approaches I don't know what else to try.
I have an application where I need to have key detection (to move a robot arm with the keyboard) but when I press enter I need to add some inputs, which should be as long as I want, just some normal input("insert here").
I know about the python libraries to get key detection, I got pynput to work successfully but it crashes my raspberry pi when I start and stop the threads a few times,I tried the Keyboard library but the whole root requirement is a let down, I also got curses to work and this seems to be solid and is (almost) not causing any issues, so detecting 1 key is not a problem.
I of course know how to name my files and get all the information that I need by doing input(), so if I had to use one of those options the job would be rather simple, the challenge comes when I try to apply both approaches together, basically detect the keys to do everything I need, and use python Input to get all the inputs from the user as soon as enter is pressed, all the libraries to detect key seems to take full control and they don't want to release it without a fight. They seem to expect the user to always require single key detection but in my case I would need to constantly turn it on and off, I couldn't figure out any efficient (or not) way to get it to work properly.
My question is:
What is the best approach to have key detection + full user input when needed with curses (or any alternative) in a non blocky way (as my code need to do some other things while listening for keys), is creating and destroying the whole thing the only alternative?
This is my current test code that I created for simplicity (which works but blocks everything while listening for keys):
import curses
import time
import os
stdscr = None
addInput = False
def SetupCurses():
global stdscr
stdscr = curses.initscr()
curses.cbreak()
stdscr.keypad(1)
def StartCurse():
global addInput
key = ''
while key != ord('q'):
key = stdscr.getch()
stdscr.addstr(str(key))
if key == ord('a'):
print("\nyou pressed a\n")
if key == 10:
print("\nyou pressed enter!\n")
addInput = True
break
def EndCurse():
curses.endwin()
while(True):
SetupCurses()
StartCurse()
EndCurse()
if addInput:
theinput = input("add your input\n")
print(theinput)
time.sleep(4)
addInput = False
#if there isn't any input to add I want the code to continue because there is non-related keys stuff to do, but of course it stopped at "StartCurse"
#if there is something to add the code can stop at addInput
The reason for the loop is because the user can save as many positions as he want, so after adding some inputs the possibility of adding more is there.
I saw people making this non-blocking by closing the curses loop after a few seconds (which stops everything anyway...) kind of getting the input by luck...something like:
def ExecuteCurses():
global AddInput
#open it and close it very quickly to grab a key if it is pressed
c = stdscr.getch()
if c == ord('a'):
print("you pressed a")
AddInput = True
time.sleep(1)
curses.endwin()

If you want a full and long user input you will need to use the curses.echo() and then use the stdscr.getstr(). That will wait for the user to press enter().
And to not block the program while getting input you need threading which you will have to import at the top of your program
And for the threading here is a link so you can find out more about threading.
I hope it answers your question

Getting input in python via the same window?

I would like to know how to get user input in python without using the command line or an input box.
Let me explain. I do not want to do this
#All code is python 3
name=input("What is your name?")
Why? When running scripts, the command line is not auto-focused. Furthermore, it pops up another window, something I do not want because I can't hit escape to close it in a hurry (Something which you may want to do if you're playing a game).
What have I tried?
I looked at WX and it's dialog function, something like this:
import wx
app=wx.App()
def text_entry(title,message):
result=None
dlg=wx.TextEntryDialog(None, message,title)
if dlg.ShowModal()==wx.ID_OK: result=dlg.GetValue()
dlg.Destroy()
return result
text_entry("Text entry","Enter something here")
While this works, it pops up another window which again, I do not want. However, it is closer to what I am ultimately looking for, because I can hit escape to make it go away.
I have tried using pygame and it's key.get_pressed() function, but it inserts a lot of the same letter into the entry, even if I gently tap the key. Also, when I implemented it into the project, it can only pick up on normal letters. Writing 26 if statements to detect key presses for a single letter with or without the shift key seems a little counter intuitive.
Finally, I am a bit hesitant to try tkinter. I happen to be blind, and from what I read, tk is very visual, which makes me concerned that it won't play nicely with my screen reader (NVDA).
So, I'm here. After searching on google for "getting input without using command line in python 3", "input in the same window", and "input without using input()" yielded nothing.
To recap, I want to accept user input without using the input() function, and without any additional windows popping up for the duration of me doing so.
Thank you.

What about this solution using the msvcrt module. At any time if you press escape then the program will exit. Python sys.exit(), and built-ins exit() and quit() all call raise SystemExit so this is just one less call to perform. If you press the enter or return key then the while loop ends and you can use the keys that were pressed later in your program as they are stored in the variable user_input. The print at the end just proves that the pressed keys are stored in user_input variable and the input() function simply to leave the window open so you can see it working.
import msvcrt
user_input = b''
while True:
pressed_key = msvcrt.getche() # getch() will not echo key to window if that is what you want
if pressed_key == b'\x1b': # b'\x1b' is escape
raise SystemExit
elif pressed_key == b'\r': # b'\r' is enter or return
break
else:
user_input += pressed_key
print('\n' + user_input.decode('utf-8')) # this just shows you that user_input variable can be used now somewhere else in your code
input() # input just leaves the window open so you can see before it exits you may want to remove

So after doing some more research, I found this:
https://codeload.github.com/Nearoo/pygame-text-input/zip/master
I think this is what I am looking for, though it still needs to be slightly modified. Thank you for the assistance

How to "continue" OR "exit" the program by pressing keys

Lets say I have 2 lines of code like this:
a = [1 , 2 , 3 , 4]
print (a)
Now I want to add something to this code to give the user 2 options:
1: press "Enter" to continue.
In this case the code should print "a"
2: press "Esc" to exit the program.
In this case the program should be stopped (e.g. exit the code).
I need to mention that I only want to use these 2 keys (Enter&Esc) NOT any key
I have been palying with raw_input and sys.exit but it did not work. Any idea how I can do it in this example?
Thanks!

You can use Keyboard module to detect keys pressed. It can be installed by using pip. You can find the documentation here. Keyboard API docs
pip install keyboard
check the below code to understand how it can be done.
import sys
import keyboard
a=[1,2,3,4]
print("Press Enter to continue or press Esc to exit: ")
while True:
try:
if keyboard.is_pressed('ENTER'):
print("you pressed Enter, so printing the list..")
print(a)
break
if keyboard.is_pressed('Esc'):
print("\nyou pressed Esc, so exiting...")
sys.exit(0)
except:
break
Output:

Code that recognises a keypress in Python 3

Is there anyway for python 3 to recognise a keypress? For example, if the user pressed the up arrow, the program would do one thing whereas if the down arrow was pressed, the program would do something else.
I do not mean the input() function where the user has to press enter after the keypress , I mean where the program recognises the keypress as some as it was pressed.
Is this question too confusing? xD

Python has a keyboard module with many features. You Can Use It In Both Shell and Console.
Install it, perhaps with this command:
pip3 install keyboard
Then use it in code like:
import keyboard #Using module keyboard
while True: #making a loop
try: #used try so that if user pressed other than the given key error will not be shown
if keyboard.is_pressed('up'): #if key 'up' is pressed.You can use right,left,up,down and others
print('You Pressed A Key!')
break #finishing the loop
else:
pass
except:
break #if user pressed other than the given key the loop will break
You can set it to multiple Key Detection:
if keyboard.is_pressed('up') or keyboard.is_pressed('down') or keyboard.is_pressed('left') or keyboard.is_pressed('right'):
#then do this
You Can Also Do Something like:
if keyboard.is_pressed('up') and keyboard.is_pressed('down'):
#then do this
It Also Detect Key For The Whole Windows.
Thanks.

I assume this is a gui program,
If using the built-in gui module Tkinter, you can use bind to connect a function to a keypress.
main.bind('<Up>', userUpkey)
Where userUpKey is a function defined in the current scope.