Develop Reference

Output of interactive python to shell variable

There is an interactive python script something like
def myfunc():
print("enter value between 1 to 10")
i=int(input())
if(i<1 or i>10):
print("again")
myfunc()
else:
print(i)
I want to store the final output which is print(i) in a shell variable. Something like
python myFile.py | read a
Above query get stuck everytime i run the command. Is it possible to do that?
Even though ( read b | python myFile.py ) | read a defeats the purpose of interactive python function but this doesn't work as well. It works if myfunc() is non-interactive(not expecting user input). The function in reality takes some input, manipulates it, and then output the result in required format. I know it would be much easier to use either python or shell, but since i already wrote the python function, was wondering if it is possible to link both. If yes, is it also possible to add only final value to shell variable rather than all the print()
Same issue happens(terminal gets stuck) when i do
python myFile.py > someFilename
However file someFilename was created even though terminal was unresponsive. It seems shell is starting both the processes at the same time which makes sense. I am guessing if somehow python myfile.py executes independently before opening the pipe it could be possible, but i may be wrong.

If you are working on Linux or other Unix variants, would you please try:
import os
def myfunc():
tty = os.open("/dev/tty", os.O_WRONLY)
os.write(tty, "enter value between 1 to 10\n")
i=int(input())
if(i<1 or i>10):
os.write(tty, "again\n")
myfunc()
else:
print(i)
BTW if your shell is bash, it will be better to say:
read a < <(python myFile.py)
Otherwise read a is invoked in the subshell and the variable a
cannot be referred in the following codes.

how can i execute python commands(?) in python script?

i wonder how to import python console in my python script.
If there are a script named script1.py, that taking string input from console.
What i want to do is that, if i give string input "print(5)" to the script1.py,
than it executes the print(5) (which will give the 5 as result as we use the python console).

Use the python eval() function, as in https://docs.python.org/3/library/functions.html#eval. That evaluates any input string as python code.
For instance:
x = 1
eval('x+1')
2
Be careful with eval though; if the string to be evaluated comes from unprotected user input, it can do anything your own python code can do.

Some functions from library works in python shell but not in a script

I'm having trouble getting certain functions from a library called art (https://github.com/sepandhaghighi/art) to run in a script, though they work fine in a shell. The script/commands entered sequentially look like this:
from art import *
randart() <(function fails in script, but succeeds in shell)
tart("test") <(different function, same library, succeeds in both shell and script)
import sys
print(sys.version)
The python version is 3.7.5 for both the shell and the script. The first function does not throw an error when run in a script, but does not give any output. Its desired output is a random ascii_art from a collection. I feel like I'm missing something really simple. Any ideas? The documentation on github reports "Some environments don't support all 1-Line arts", however they are the same python version on the same machine. Are there other portions of the environment that could be the cause?

You need to print randart() while writing in script. Make a habit of using print() for everything while printing. Shell is the place which returns the value by default whereas you need to tell the script window what to do with any name or function.
so use this:
from art import *
print(randart())

in the shell it is implicitly printed ... in a script you must explicitly
print(randart())

Is there an interpreter for Python similar to Pry for Ruby? [duplicate]

Is there a way to programmatically force a Python script to drop into a REPL at an arbitrary point in its execution, even if the script was launched from the command line?
I'm writing a quick and dirty plotting program, which I want to read data from stdin or a file, plot it, and then drop into the REPL to allow for the plot to be customized.

I frequently use this:
def interact():
import code
code.InteractiveConsole(locals=globals()).interact()

You could try using the interactive option for python:
python -i program.py
This will execute the code in program.py, then go to the REPL. Anything you define or import in the top level of program.py will be available.

Here's how you should do it (IPython > v0.11):
import IPython
IPython.embed()
For IPython <= v0.11:
from IPython.Shell import IPShellEmbed
ipshell = IPShellEmbed()
ipshell() # this call anywhere in your program will start IPython
You should use IPython, the Cadillac of Python REPLs. See http://ipython.org/ipython-doc/stable/interactive/reference.html#embedding-ipython
From the documentation:
It can also be useful in scientific
computing situations where it is
common to need to do some automatic,
computationally intensive part and
then stop to look at data, plots, etc.
Opening an IPython instance will give
you full access to your data and
functions, and you can resume program
execution once you are done with the
interactive part (perhaps to stop
again later, as many times as needed).

You can launch the debugger:
import pdb;pdb.set_trace()
Not sure what you want the REPL for, but the debugger is very similar.

To get use of iPython and functionality of debugger you should use ipdb,
You can use it in the same way as pdb, with the addition of :
import ipdb
ipdb.set_trace()

I just did this in one of my own scripts (it runs inside an automation framework that is a huge PITA to instrument):
x = 0 # exit loop counter
while x == 0:
user_input = raw_input("Please enter a command, or press q to quit: ")
if user_input[0] == "q":
x = 1
else:
try:
print eval(user_input)
except:
print "I can't do that, Dave."
continue
Just place this wherever you want a breakpoint, and you can check the state using the same syntax as the python interpreter (although it doesn't seem to let you do module imports).
It's not very elegant, but it doesn't require any other setup.

Great answers above, but if you would like this functionality in your IDE. Using Visual Studio Code (v1.5.*) with Python Setup:
Highlight the lines you would like to run and
right click and select Run Selection/Line in Interactive Window from the drop down.
Press shift + enter on your keyboard.
Right click on the Python file you want to execute in the file explorer and select Run Current File in Interactive Window
This will launch an interactive session, with linting, code completion and syntax highlighting:
Enter the code you would like to evaluate, and hit shift + enter on your keyboard to execute.
Enjoy Python!

How to drop into REPL (Read, Eval, Print, Loop) from Python code

Is there a way to programmatically force a Python script to drop into a REPL at an arbitrary point in its execution, even if the script was launched from the command line?
I'm writing a quick and dirty plotting program, which I want to read data from stdin or a file, plot it, and then drop into the REPL to allow for the plot to be customized.

I frequently use this:
def interact():
import code
code.InteractiveConsole(locals=globals()).interact()

You could try using the interactive option for python:
python -i program.py
This will execute the code in program.py, then go to the REPL. Anything you define or import in the top level of program.py will be available.

Here's how you should do it (IPython > v0.11):
import IPython
IPython.embed()
For IPython <= v0.11:
from IPython.Shell import IPShellEmbed
ipshell = IPShellEmbed()
ipshell() # this call anywhere in your program will start IPython
You should use IPython, the Cadillac of Python REPLs. See http://ipython.org/ipython-doc/stable/interactive/reference.html#embedding-ipython
From the documentation:
It can also be useful in scientific
computing situations where it is
common to need to do some automatic,
computationally intensive part and
then stop to look at data, plots, etc.
Opening an IPython instance will give
you full access to your data and
functions, and you can resume program
execution once you are done with the
interactive part (perhaps to stop
again later, as many times as needed).

You can launch the debugger:
import pdb;pdb.set_trace()
Not sure what you want the REPL for, but the debugger is very similar.

To get use of iPython and functionality of debugger you should use ipdb,
You can use it in the same way as pdb, with the addition of :
import ipdb
ipdb.set_trace()

I just did this in one of my own scripts (it runs inside an automation framework that is a huge PITA to instrument):
x = 0 # exit loop counter
while x == 0:
user_input = raw_input("Please enter a command, or press q to quit: ")
if user_input[0] == "q":
x = 1
else:
try:
print eval(user_input)
except:
print "I can't do that, Dave."
continue
Just place this wherever you want a breakpoint, and you can check the state using the same syntax as the python interpreter (although it doesn't seem to let you do module imports).
It's not very elegant, but it doesn't require any other setup.

Great answers above, but if you would like this functionality in your IDE. Using Visual Studio Code (v1.5.*) with Python Setup:
Highlight the lines you would like to run and
right click and select Run Selection/Line in Interactive Window from the drop down.
Press shift + enter on your keyboard.
Right click on the Python file you want to execute in the file explorer and select Run Current File in Interactive Window
This will launch an interactive session, with linting, code completion and syntax highlighting:
Enter the code you would like to evaluate, and hit shift + enter on your keyboard to execute.
Enjoy Python!