Re: [Tutor] postgreSQL + psycopg2

2016-05-10 Thread Peter Otten 
nitin chandra wrote:

> Thanks Alan, Peter
> 
> but didn't work
> 
> nextrow=(cursor1.execute(query, (design1,))).fetchone()
> AttributeError: 'NoneType' object has no attribute 'fetchone'

Try without the method chaining:

cursor1.execute(query, (design1,))
nextrow = cursor1.fetchone()

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Re: [Tutor] postgreSQL + psycopg2

2016-05-10 Thread nitin chandra 
IT WORKED 

THANK YOU SSS MUCH ...phew .. Thank you

here is the result.

1
('Supervisor',)

1
Vinayak
Salunke
1

Now I need to remove the braces and quotes .. :)

Thank you

Nitin

On 10 May 2016 at 12:30, Peter Otten <__pete...@web.de> wrote:
> nitin chandra wrote:
>
>> Thanks Alan, Peter
>>
>> but didn't work
>>
>> nextrow=(cursor1.execute(query, (design1,))).fetchone()
>> AttributeError: 'NoneType' object has no attribute 'fetchone'
>
> Try without the method chaining:
>
> cursor1.execute(query, (design1,))
> nextrow = cursor1.fetchone()
>
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Re: [Tutor] is there a better way to do this?

2016-05-10 Thread Chris Roy-Smith 

On 10/05/16 12:01, Steven D'Aprano wrote:

On Mon, May 09, 2016 at 06:13:32PM +1000, Chris Roy-Smith wrote:


data = [[" " for x in range(9)] for y in range(count)]
for (ddate, mood, walk, lag, sleep) in curs:
 data[row][0]=ddate
 data[row][1]=mood
 data[row][2]=walk
 data[row][3]=lag
 data[row][4]=sleep
 row +=1

While I don't know a better way to do this, it seems a bit awkward, is
there a better way?

Hmmm, it's hard to be sure because we don't really know what count is.
Do you want a bunch of empty rows at the end? My guess is No.

In your code above, you initialise each row with ten spaces, and only
replace five of them. So assuming you need the extra five spaces:

data = [record + [" "]*5 for record in curs]

provided curs returns lists, rather than tuples. (If not, it's
easy to just convert using `list(record)`.

If you don't need the extra five columns, the code is even simpler:

data = list(curs)

Thank you,
that's much better
I thought I needed the extra columns, but I changed things to use 2 
lists of lists
(one generated with the above line and another to hold my calculated 
results)




What if you do want extra blank rows? Easiest to just add them at the
end:

# initialise data as above, then add blanks
for i in range(how_many_extra_rows):
 data.append([" "]*10)

which can be simplified to:

data.extend([[" "]*10 for i in range(how_many_extra_rows)])





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Re: [Tutor] is there a better way to do this?

2016-05-10 Thread Chris Roy-Smith 

On 10/05/16 07:03, Ondřej Rusek wrote:

Dne 9.5.2016 v 10:13 Chris Roy-Smith napsal(a):

Hi
Python 3.4 Linux (ubuntu)

This code does what I want.
curs is the result of a mysql query


data = [[" " for x in range(9)] for y in range(count)]
for (ddate, mood, walk, lag, sleep) in curs:
data[row][0]=ddate
data[row][1]=mood
data[row][2]=walk
data[row][3]=lag
data[row][4]=sleep
row +=1


if you want 'lists in list' (like your solution):

data = []
for ddate, mood, walk, lag, sleep in curs:
data += [ [ddate, mood, walk, lag, sleep] ]

or 'tuples in list':

data = []
for ddate, mood, walk, lag, sleep in curs:
  data += [ (ddate, mood, walk, lag, sleep) ]

but for 'tuples in list'... simple:

data = []
for record in curs:
  data += [record]



Thanks,
I hadn't considered having a second list of lists for my calculations,
Your solution is the sort of thing I was looking for.
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[Tutor] Rate transition from 60hz to 1000hz

2016-05-10 Thread David Wolfe 
Good Evening;

I'm collecting both video and force plate data, and I need to be able to
synchronize the two, so I can make some calculations.  The video data is at
60hz, and the force plate data is at 1000hz.  I don't want to truncate the
force plate data.

So, how do I perform a rate transition (or interpolation, or whatever) to
expand the data that is captured at 60hz to be able to synchronize it with
the data that has been captured at 1000hz?

Also, if I'm not using the correct terms, please let me know.  I'm new to
Python and programing, and I'm trying to learn as fast as i can.

Thanks,
David
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Re: [Tutor] Rate transition from 60hz to 1000hz

2016-05-10 Thread Alan Gauld via Tutor 
On 10/05/16 04:08, David Wolfe wrote:

> I'm collecting both video and force plate data, and I need to be able to
> synchronize the two, so I can make some calculations.  The video data is at
> 60hz, and the force plate data is at 1000hz.  I don't want to truncate the
> force plate data.

I have no idea what force plate data is but assuming it's nothing
special you have two sets of data, one at 1000Hz and one at 60Hz.
And you want to join them together at the appropriate points.

The problem is that 60 is not an exact factor of 1000 so you
will need to decide how you align the samples.

> So, how do I perform a rate transition (or interpolation, or whatever) to
> expand the data that is captured at 60hz to be able to synchronize it with
> the data that has been captured at 1000hz?

Interpolation over such a large sample range is tricky and risky.
The simplest way is to assume a straight line between samples.
So each interpolated value is just S2-S1/17 higher than the
previous value(S1).

A better way is to try to determine the current curve shape and apply
that. But it's much harder to do unless you know what kind of data to
expect!

> Also, if I'm not using the correct terms, please let me know.  I'm new to
> Python and programing, and I'm trying to learn as fast as i can.

This has nothing to do with Python or even programming per se.
Its really a math question. The same issues would apply if you
were tabulating the data by hand on paper.

That having been said, there may be some math libraries around
that you could use to do the sums for you. But it's not my area of
expertise so maybe some of the other tutor members will suggest
something in numpy or pandas or whatever.

-- 
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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Re: [Tutor] Rate transition from 60hz to 1000hz

2016-05-10 Thread Steven D'Aprano 
On Mon, May 09, 2016 at 11:08:37PM -0400, David Wolfe wrote:
> Good Evening;
> 
> I'm collecting both video and force plate data, and I need to be able to
> synchronize the two, so I can make some calculations.  The video data is at
> 60hz, and the force plate data is at 1000hz.  I don't want to truncate the
> force plate data.
> 
> So, how do I perform a rate transition (or interpolation, or whatever) to
> expand the data that is captured at 60hz to be able to synchronize it with
> the data that has been captured at 1000hz?

You need to explain in more detail what you actually have. What format 
is this data? What were you planning on doing with it? What sort of 
calculations were you intending to do? Are you using Numpy for the 
calculations?


-- 
Steve
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Re: [Tutor] Rate transition from 60hz to 1000hz

2016-05-10 Thread Oscar Benjamin 
On 10 May 2016 at 04:08, David Wolfe  wrote:
> Good Evening;
>
> I'm collecting both video and force plate data, and I need to be able to
> synchronize the two, so I can make some calculations.  The video data is at
> 60hz, and the force plate data is at 1000hz.  I don't want to truncate the
> force plate data.
>
> So, how do I perform a rate transition (or interpolation, or whatever) to
> expand the data that is captured at 60hz to be able to synchronize it with
> the data that has been captured at 1000hz?
>
> Also, if I'm not using the correct terms, please let me know.  I'm new to
> Python and programing, and I'm trying to learn as fast as i can.

The normal term for this is "resampling" and scipy has a function
called resample that does exactly this. Here's a demonstration:

>>> from scipy.signal import resample
>>> plate_signal = [1, 2, 1, 3, 1, 4, 2, 3, 4, 2]
>>> video_signal = [7, 8, 4]
>>> video_resampled = list(resample(video_signal, len(plate_signal)))
>>> video_resampled
[7.0009, 8.230109890796971, 8.735715605706849,
8.3236929465402536, 7.1514205649637077, 5.667,
4.4365567758696969, 3.9309510609598171, 4.3429737201264125,
5.5152461017029593]

This resamples the signal using interpolation. Notice that the last
samples of resample are increasing away from 4 (towards 7). This is
because resample uses a DFT-based method so it implicitly assumes that
the signal is periodic. This leads to a bit of distortion at the end
of your resampled signal - often that doesn't matter but it's worth
noticing.

You can read more about resample here:

http://docs.scipy.org/doc/scipy-0.16.0/reference/generated/scipy.signal.resample.html

I've added a list call because resample returns a numpy array. Do you
know what that is?

Presumably in your application video_signal is actually a 3D array
since at each frame you would have a 2D array of pixel values.
Resamples can handle this case too but exactly how to call it depends
on what sort of array you're using to store the video data.

I'm assuming here that you want to work offline. If you actually want
to do this computation online (as the data comes in) then you'd need
something different.

--
Oscar
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Re: [Tutor] postgreSQL + psycopg2

2016-05-10 Thread Danny Yoo 
> here is the result.
>
> 1
> ('Supervisor',)
> 
> 1
> Vinayak
> Salunke
> 1
>
> Now I need to remove the braces and quotes .. :)


By the way, be very careful about generating HTML via naive string
concatenation.  If you can use a template engine such as Jinja
(http://jinja.pocoo.org/), please do so.


The main problem here is that the content you're using from the
database might have characters that look "html"-ish, in which case the
use of string concatenation is a vector for a Bobby-tables-like
injection attack.

https://xkcd.com/327/

If you can't use a templating engine that knows about HTML escaping,
then you still need to add html escaping where the rows are being
constructed here:

for row in line1:
print ""+str(row)+""

See: https://docs.python.org/3/library/html.html#html.escape

Basically, any place where something "structured" (SQL queries, HTML)
is being constructed from something unstructured (string
concatenation), that's where injection attacks like to live.  Be
careful.


Hope this helps!
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Re: [Tutor] postgreSQL + psycopg2

2016-05-10 Thread Alan Gauld via Tutor 
On 10/05/16 08:33, nitin chandra wrote:

> here is the result.
> 
> 1
> ('Supervisor',)
> 
> 1
> Vinayak
> Salunke
> 1
> 
> Now I need to remove the braces and quotes .. :)

No you don't. Those are just part of the string representation
that Python uses when printing a string inside a tuple.

If you print nextRow[0] instead of nextRow you
will get the bare string.

BTW Why are you using triple quotes? You only need them if
your string wraps over multiple lines. Single quotes (" or ')
will be fine for your purposes and are easier to type...

-- 
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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Re: [Tutor] postgreSQL + psycopg2

2016-05-10 Thread nitin chandra 
Thank you Danny, Alan,

@ Danny

I added 'str(formt(line1[0]))'  will this do ?

@ Alan

I did just that  nextRow[0]

Triple quotes .. there is some part of code in multi-line 
so... me being just lazyyy ... copy pasted / edited ... and left what
is working . just my excuse :P




On 11 May 2016 at 03:57, Alan Gauld via Tutor  wrote:
> On 10/05/16 08:33, nitin chandra wrote:
>
>> here is the result.
>>
>> 1
>> ('Supervisor',)
>> 
>> 1
>> Vinayak
>> Salunke
>> 1
>>
>> Now I need to remove the braces and quotes .. :)
>
> No you don't. Those are just part of the string representation
> that Python uses when printing a string inside a tuple.
>
> If you print nextRow[0] instead of nextRow you
> will get the bare string.
>
> BTW Why are you using triple quotes? You only need them if
> your string wraps over multiple lines. Single quotes (" or ')
> will be fine for your purposes and are easier to type...
>
> --
> 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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Re: [Tutor] postgreSQL + psycopg2

2016-05-10 Thread Danny Yoo 
On Tue, May 10, 2016 at 10:37 PM, nitin chandra  wrote:
> Thank you Danny, Alan,
>
> @ Danny
>
> I added 'str(formt(line1[0]))'  will this do ?


Unfortunately, I don't know: what makes me hesitant is the following:

* The above is doing something just to line1[0], which looks odd.  Why
just line1[0]?

* What's the type of line1?  Is it a list of strings?  If so, then
calling str() on a string is redundant.

* I don't know what "formt" is.

So, yeah, I have enough questions and uncertainty that I need to
hedge.  This is not to say that you got it right or wrong, but rather
that I don't have enough information to decide either way.  There are
a lots of little details to get right when we program.  Rather than
handwave and assume that things are ok, I'll be truthful and admit my
ignorance.


Hope that makes sense!
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