[Tutor] Help with List
Hello Team, I am noob to programming. I am trying to remove a item from a list. The item that I am trying to remove has multiple entries in the list. I am not able to remove all the entries. Please Help. The code is in the attachment. -- Thanks & Regards Anurag Vyas ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Help with List
On Sun, Jul 26, 2015 at 10:04:19AM +0530, Anurag Vyas wrote:
> Hello Team,
> I am noob to programming. I am trying to remove a item from a list. The
> item that I am trying to remove has multiple entries in the list. I am not
> able to remove all the entries.
> Please Help. The code is in the attachment.
There is no attachment. Perhaps you forgot to attach it?
In general, if your code is less than 20 or 30 lines, you should just
include it in the body of your email. If your code is more than 30
lines, you should simplify it so that it is smaller.
To delete a single item from a list:
alist = ['a', 'b', 'c', 'd', 'e']
alist.remove('b')
To delete multiple entries with the same value:
alist = ['a', 'b', 'c', 'b', 'd', 'b', 'e', 'b', 'b']
try:
while True:
alist.remove('b')
except ValueError:
pass
but this will probably be more efficient:
alist = ['a', 'b', 'c', 'b', 'd', 'b', 'e', 'b', 'b']
alist = [item for item in alist if item != 'b']
That last one is called a "list comprehension", and is a short cut for a
for-loop like this:
tmp = []
for item in alist:
if item != 'b':
tmp.append(item)
alist = tmp
--
Steve
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Re: [Tutor] How to generate a pure tones and random noise using Python?
Hi Laura, Thanks for you helpful reply, and it is exactly what I want. I'm going to learn Python from write a ears training program. ;-) And Is there have a library to scope(print) this wave form? (real-time and non real-time) I have already started to learn "generate audio with python", Thank you. :-) Paul Z > To: p...@whoosh.cn > CC: tutor@python.org; l...@openend.se > From: l...@openend.se > Subject: Re: [Tutor] How to generate a pure tones and random noise using > Python? > Date: Sat, 25 Jul 2015 22:35:24 +0200 > > In a message of Sat, 25 Jul 2015 19:15:31 +0800, Paul Z writes: >>Hi All, >> >>I try to train my listening by using python. (estimating the frequency of >>sound) >>So... Are there some way to generate a fixed frequency sound in different >>waves (eg. Sine Wave, Saw Wave, Triangle Wave etc.) and different random >>noise. (eg. white noise & pink noise) ? >> >>I have search in web, some people say that I can use winsound which can >>generate a fixed frequency beep. However, It is Windows only. (I'm under >>Linux) and I think It is not a professional library to generate audio signal. >> >>How about pygame? and some examples? >>any ideas? >> >>Thanks >> >>Paul Z >>___ >>Tutor maillist - Tutor@python.org >>To unsubscribe or change subscription options: >>https://mail.python.org/mailman/listinfo/tutor > > I think you want this: > https://zach.se/generate-audio-with-python/ > https://github.com/zacharydenton/wavebender > > pygame will not give you want you want. > > blender might. I am not sure but worth googling for. > > Laura > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How to generate a pure tones and random noise using Python?
Hi Laura,
I just have read this webpage about Generate Audio with Python.
It seem writing by Python 2? Esp. itertools (izip, imap).
I try to change izip and imap to zip and map, but I get error:
beatfreq, amplitude = remainder.split('/')
ValueError: need more than 1 value to unpack
Are there some way to conver it to the code of Python 3?
I'm too anxious to hear the sound from Python though I'm a absolute beginner.
Many thanks
Paul Z
> From: p...@whoosh.cn
> To: l...@openend.se
> Date: Sun, 26 Jul 2015 19:29:19 +0800
> Subject: Re: [Tutor] How to generate a pure tones and random noise using
> Python?
> CC: tutor@python.org
>
> Hi Laura,
>
> Thanks for you helpful reply, and it is exactly what I want.
>
> I'm going to learn Python from write a ears training program. ;-)
> And Is there have a library to scope(print) this wave form? (real-time and
> non real-time)
>
> I have already started to learn "generate audio with python", Thank you. :-)
>
> Paul Z
>
>
>> To: p...@whoosh.cn
>> CC: tutor@python.org; l...@openend.se
>> From: l...@openend.se
>> Subject: Re: [Tutor] How to generate a pure tones and random noise using
>> Python?
>> Date: Sat, 25 Jul 2015 22:35:24 +0200
>>
>> In a message of Sat, 25 Jul 2015 19:15:31 +0800, Paul Z writes:
>>>Hi All,
>>>
>>>I try to train my listening by using python. (estimating the frequency of
>>>sound)
>>>So... Are there some way to generate a fixed frequency sound in different
>>>waves (eg. Sine Wave, Saw Wave, Triangle Wave etc.) and different random
>>>noise. (eg. white noise & pink noise) ?
>>>
>>>I have search in web, some people say that I can use winsound which can
>>>generate a fixed frequency beep. However, It is Windows only. (I'm under
>>>Linux) and I think It is not a professional library to generate audio signal.
>>>
>>>How about pygame? and some examples?
>>>any ideas?
>>>
>>>Thanks
>>>
>>>Paul Z
>>>___
>>>Tutor maillist - Tutor@python.org
>>>To unsubscribe or change subscription options:
>>>https://mail.python.org/mailman/listinfo/tutor
>>
>> I think you want this:
>> https://zach.se/generate-audio-with-python/
>> https://github.com/zacharydenton/wavebender
>>
>> pygame will not give you want you want.
>>
>> blender might. I am not sure but worth googling for.
>>
>> Laura
>>
>
> ___
> Tutor maillist - Tutor@python.org
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Re: [Tutor] Socket Module
Hello Nym,
Here is the updated code: https://bpaste.net/show/358583e1a0bd
It's short. I have included inline here:
import socket
ListOfIPAddresses = []
with open('top500ips.csv', 'r') as f:
for line in f:
line = line.strip()
ListOfIPAddresses.append(line)
for address in ListOfIPAddresses:
try:
ResolvedAddresses = socket.gethostbyaddr(address)
except:
print('No Resolution Available')
print(ResolvedAddresses)
The issue that I am running into now is that for some reason, the
script is not resolving known-public IP addresses that I am
passing through. For example, some of the IPs, that I have used
are for sites like facebook (173.252.120.6) github
(207.97.227.239), however the script is not able to resolve them.
But its interesting that I am able to resolve them using nslookup
on windows command prompt. Which means my laptop's DNS setting is
fine.
The apparent (?) DNS lookup failure
---
At time X, you run your Python program and something (perhaps in the
DNS resolution process) fails and you see "No Resolution Available",
but you do not know what has failed, nor for which address lookup.
At time Y, you run 'nslookup' at the shell prompt, receive an answer
and conclude that your script is operating properly. While this is
may appear logical, it is an incorrect conclusion.
One coding error (a dangerous habit to perpetuate)
--
When performing the DNS lookup, you are using something called
a 'bare except'. This will catch any and all errors, even if it's
something unrelated like, for example, a signal. This is a bad and
dangerous habit. In general, you should catch only the exceptions
that you can do something about.
In addition, this will offer you more information about the problem.
Here's a simple example, where I'm only changing two lines:
for address in ListOfIPAddresses:
try:
ResolvedAddresses = socket.gethostbyaddr(address)
except socket.herror as e:
print("No resolution available for %s: %s" % (address, e))
This will give you a little more information about what,
specifically, the failure is in your call to socket.gethostbyaddr()
Comment on NXdomain responses
-
I picked at random an address that had no PTR record and tried to
call socket.gethostbyaddr('8.97.227.2'). What do you think I got
for my trouble? When running through the code block above, I saw
the following output to my terminal:
No resolution available for 8.97.227.2: [Errno 0] Resolver Error 0 (no error)
In short, there is no guarantee that anybody has properly set up
reverse DNS entries (DNS PTR records) for the addresses you are
looking up. Although the vast majority of lookups occur
successfully and smoothly, there are many things that can go wrong
in the network and on an end host which can cause transient errors
during DNS lookups, and it is possible that you have already
encountered some of these problems (even though I would not expect
to hit very many errors looking up PTR records for only 500 IPs).
May I wish you good luck resolving not just your addresses, but also
your problem!
-Martin
--
Martin A. Brown
http://linux-ip.net/
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Re: [Tutor] How to generate a pure tones and random noise using Python?
>
>
> I just have read this webpage about Generate Audio with Python.
> It seem writing by Python 2? Esp. itertools (izip, imap).
> I try to change izip and imap to zip and map, but I get error:
>
>
> beatfreq, amplitude = remainder.split('/')
>
> ValueError: need more than 1 value to unpack
>
> Are there some way to conver it to the code of Python 3?
>
> I'm too anxious to hear the sound from Python though I'm a absolute
> beginner.
>
> Many thanks
>
> Paul Z
>
>
If you are using Python 3, replace calls to itertools.izip and
itertools.imap with simply "zip" and "map" respectively. Why not just use
Pyton2 instead, as there may be other things that will break.
beatfreq, amplitude =
>
> remainder.split('/')
This throwing an exception means there is an issue with the data you are
trying to split, not necessarily a Py2 vs Py3 thing. What string is
assigned `remainder`?
--
*Pablo Lucena*
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Re: [Tutor] How to generate a pure tones and random noise using Python?
On 25/07/15 12:15, Paul Z wrote:
Are there some way to generate a fixed frequency sound in different
> waves (eg. Sine Wave, Saw Wave, Triangle Wave etc.) and
> different random noise. (eg. white noise & pink noise) ?
While there are several options in Python (check out the
Activestate recipes) the simplest way on Linux may be to
create a file with the relevant signal and then play that
through aplay using the subprocess module.
One such module(by B Walker) that I found on Activestate
is this (slightly tweaked):
def sinebeep():
header=[ 82, 73, 70, 70, 100, 31, 0, 0, 87, 65, 86, 69,
102, 109, 116, 32, 16, 0, 0, 0, 1, 0, 1, 0,
64, 31, 0, 0, 64, 31, 0, 0, 1, 0, 8, 0, 100,
97, 116, 97, 64, 31, 0, 0 ]
waveform=[ 79, 45, 32, 45, 79, 113, 126, 113 ]
wavefile=open("beep.wav", "w+")
for hdr in header:
wavefile.write(chr(hdr))
for sample in range(0, 1000, 1):
for wf in waveform:
wavefile.write(chr(wf))
wavefile.close()
if __name__ == '__main__':
sinebeep()
You can then play the resultant file with
$ aplay beep.wav #you might need sudo
Its not very clever but you could create a series of beep
files each with a different frequency.
PS.
There is also a command line program called beep that does
what you want but it didn't work for me... YMMV
HTH
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos
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