Re: [Tutor] new to python

[Anish Tambe]

> for line in file:

This line is not required as the you have opened your file to 'f'.
'file' is a built-in class. Type -
help(file)
on the interpreter to know more about it.

> for line in f:
> print(line.rstripe())
> f.close()

Are you sure that you need to close the file after reading each line?

>
> I want to try the different methods of opening files and reading them.
and processing the data.  from there I will then start with writing to
files.

Bonus : read about the 'with' keyword.

> any idea why that does not work?

When you say the code does not work, you should provide the exact error or
stacktrace that you see.

Thanks,
Anish
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Re: [Tutor] Help with Python Queue

[Anish Tambe]

> AttributeError: Queue instance has no attribute 'taskdone'

Method name is task_done (not taskdone)

https://docs.python.org/2/library/queue.html#Queue.Queue.task_done
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Re: [Tutor] infix to postfix eval

[Anish Tambe]

On Sun, Aug 2, 2015 at 9:39 AM, Quiles, Stephanie
 wrote:
>
> hello again!
>
> I have to unify these methods so that i can enter an infix, convert it to a 
> postfix and then solve. Here are the methods

At the end of your code I added this -

inFixExpr = raw_input("Enter infix string : ")
postFixExpr = infixToPostfix(inFixExpr)
print("The postfix string is:  " + postFixExpr)
value = postfixEval(postFixExpr)
print("The final result is:  " + str(value))

And this gives me output -
$ python postfix.py
5 3 4 2 - ^ *
A B + C * D E - F G + * -
Enter infix string : ( 8 + 2 ) * ( 2 + 4 )
The postfix string is:  8 2 + 2 4 + *
The final result is:  60


> if token in "ABCDEFGHIJKLMNOPQRSTUVWXYZ" or token in "0123456789":

Instead of the above line, you can do this -
 if token in string.uppercase or token in string.digits:
Import string module first.

>>> import string
>>> string.uppercase
'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
>>> string.digits
'0123456789'
>>>

Thanks,
Anish
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Re: [Tutor] Python GPIO Code Help Needed

[Anish Tambe]

On Sun, Oct 26, 2014 at 6:35 AM, Bill Bright  wrote:

> I have been working on a piece of code that I got from another tutorial.
> The code polls the GPIO pins on a Raspberry Pi. When it detects a switch
> being flipped, it plays a corresponding audio file. My problem is, if the
> switch remains flipped, the audio repeats again and again. What I would
> like to do is when a switch is flipped have the audio play, then have the
> code pause until the switch is returned to normal (not repeating the
> audio), and then return to the while loop to poll for the next switch flip.
> I am apparently not smart enough to figure out the correct code. I really
> need some help with this and I would appreciate any assistance.
>
> Here is the code I'm working with.
>
> #!/usr/bin/env python
> from time import sleep
> import os
> import RPi.GPIO as GPIO
> GPIO.setmode(GPIO.BCM)
> GPIO.setup(23, GPIO.IN)
> GPIO.setup(24, GPIO.IN)
> GPIO.setup(25, GPIO.IN)
> while True:
> if ( GPIO.input(23) == False ):
> os.system('mpg321 -g 95 a.mp3')
> if ( GPIO.input(24) == False ):
> os.system('mpg321 -g 95 b.mp3')
> if ( GPIO.input(25)== False ):
> os.system('mpg321 -g 95 c.mp3')
> sleep(1.1);
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Using callbacks instead of polling might help.

You can do something like this -

def play(channel) :
#your action here
if channel == 23 :
os.system('mpg321 -g 95 a.mp3')

GPIO.add_event_detect(23, GPIO.RISING, callback=play)

and similarly for the other pins.

Check the "Events and Callback Functions" section of this tutorial -
http://makezine.com/projects/tutorial-raspberry-pi-gpio-pins-and-python/

Cheers,
Anish Tambe
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Re: [Tutor] Help with running an API

[Anish Tambe]

The usage of the api as documented here - https://github.com/zachwill/fred
- suggests :

>>> import fred

# Save your FRED API key.
>>> fred.key('my_fred_api_key')

# Interact with economic data categories.
>>> fred.category()
...

Cheers,
Anish Tambe
On 26 Oct 2014 00:23, "Joel Goldstick"  wrote:

> On Sat, Oct 25, 2014 at 12:08 PM, Mark Meanwell 
> wrote:
> > Hi Folks - new to python and trying to run an API. Running version
> 2.7.3. on
> > Windows 7 machine.
> >
> >  Here is the scenario for the given API (FRED API in this case):
> >
> > easy_install Fred from C:\ - this installs to C:\site packages
> >
> > then I fire up the python shell and run file created for fred api:
> >
> > from fredapi import Fred
> > fred = Fred(api_key='my api key')
> > data = fred.get_series('SP500')
> >
> > keep getting below error message:
> > ImportError: cannot import name Fred
> >
> > thanks for any suggestions!
>
> I'm not familiar with FRED, but a quick look on stackoverflow used the
> lowercase name to import
>
> >
> >
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>
>
>
> --
> Joel Goldstick
> http://joelgoldstick.com
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