ImportError: No module named quick2wire.i2c

[0x0000]

Hello,

I have been following this tutorial to set-up my ADC Pi,

http://elinux.org/RPi_ADC_I2C_Python,

On third point of step 3, it says,

enable Python to access the API by adding
export PYTHONPATH=$PYTHONPATH:$HOME/quick2wire-python-api to the end of ~/.profile

what is meant by

~./profile

there ?

I simply typed this line in my Linux Terminal,

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export PYTHONPATH=$PYTHONPATH:$HOME/quick2wire-python-api

and rebooted the RPi

I then followed the step 5,

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Download and run the demo script
download it with: wget http://www.andrewscheller.co.uk/adc_demo.py
make it executable with: chmod +x adc_demo.py
run it with: ./adc_demo.py

But when I am running it, I am getting this error,

root@raspberrypi:/home/pi# python adc_demo.py
Traceback (most recent call last):
File "adc_demo.py", line 11, in <module>
import quick2wire.i2c as i2c
ImportError: No module named quick2wire.i2c

What am I doing wrong ?

[DeeJay]

On third point of step 3, it says,

enable Python to access the API by adding
export PYTHONPATH=$PYTHONPATH:$HOME/quick2wire-python-api to the end of ~/.profile

what is meant by

~./profile

there ?

It is a file. The name of the file is .profile (the ' . ' is important)
It is at the 'top' level of the filespace allocated to the user running the command. (That's what ' ~/ ' means )

I simply typed this line in my Linux Terminal,

Code: Select all

export PYTHONPATH=$PYTHONPATH:$HOME/quick2wire-python-api

and rebooted the RPi

'export' does not persist over reboots - that's why you have to put it in a file to be run when you log in.

That explains the resulting errors -

root@raspberrypi:/home/pi# python adc_demo.py
Traceback (most recent call last):
File "adc_demo.py", line 11, in <module>
import quick2wire.i2c as i2c
ImportError: No module named quick2wire.i2c

What am I doing wrong ?

Not following the instructions!

[0x0000]

It is not working yet,
I have edited the ~/.profile file,

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if [ "$BASH" ]; then
  if [ -f ~/.bashrc ]; then
    . ~/.bashrc
  fi
fi

mesg n
export PYTHONPATH=$PYTHONPATH:$HOME/quick2wire-python-api

I am still getting the same error even after saving the file and rebooting RPi.
When I tried to echo $PYTHONPATH, It shows nothing at all just a blank line.

[DeeJay]

I think the advice in the tutorial may be less-than-perfect, but you seem to be working from a different base copy of ~/.profile. This is on a recent (Oct 2013) install of Raspbian.

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less .profile
# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.

# the default umask is set in /etc/profile; for setting the umask
# for ssh logins, install and configure the libpam-umask package.
#umask 022

# if running bash
if [ -n "$BASH_VERSION" ]; then
    # include .bashrc if it exists
    if [ -f "$HOME/.bashrc" ]; then
        . "$HOME/.bashrc"
    fi
fi

# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

echo "Before change - "
echo $PYTHONPATH
export PYTHONPATH=$PYTHONPATH:$HOME/quick2wire-python-api
echo "After change - "
echo $PYTHONPATH
echo "Leaving .profile... "

Results in -

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Last login: Thu Oct 31 15:24:28 2013 from 192.168.1.16
Before change -

After change -
:/home/pi/quick2wire-python-api
Leaving .profile...
pi@raspberrypi ~ $

It seems that the variable is initially empty or undefined, and the " : " operator gets taken as a literal rather than as an instruction to concatenate the strings.

But your .profile is different to start with, and you don't get the same result from 'echo $PYTHONPATH'

I've had a quick Google around and can't see a fix for this. As long as PYTHONPATH is initially empty then just setting it to the new value will work, but it's not futureproof.

[0x0000]

Thank you, I didn't get everything you write, But when I export it from the command line and prints the PythonPath , it worked !

Thanks again.

P.S: I am still getting error in running the Python script hopefully you will help me fixing it too,

http://www.raspberrypi.org/phpBB3/viewt ... 86#p446386