matplotlib-users Mailing List for matplotlib

On Fri, Jun 10, 2011 at 10:50:21PM -0500, Benjamin Root wrote:
Hi Ben and Scott and all,

>    Admittedly, these following examples are for dates (and might even need to
>    be updated...)
>    [2]http://matplotlib.sourceforge.net/examples/api/date_demo.html
>    [3]http://matplotlib.sourceforge.net/examples/api/date_index_formatter.html
> 
>    There are others as well.

I see, thanks (all your examples here are pretty helpful for
understanding matplotlib somebit better - even so I'm using the
Formatter-Function now).

marco

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   V_/_                     http://www.calmar.ws

Hi Karthik,

I cannot find any problem with your code. You are mixing modules a little
too much to my taste but it's not a technical problem.

Loading and saving the data works flawless here. Attached is an infile and a
modified script, please try this.

2011/6/11 Karthikraja Velmurugan <vel...@gm...>

> *Hi Daniel, *
> * *
> *I used the code but there is small issue. I forgot to mention that my
> values are signed and unsigned decimal values. *
> *My values look like this
> *
>  0.0023 -0.0456 0.0419 0.094  -0.0004 0.0236 -0.0237 -0.0043  -0.0718
> 0.0095 0.0592 -0.0417  0.0023 0.0386 -0.0023 -0.0236  -0.1045 0.098
> -0.0006 0.0516  0.0463 -0.0035 -0.0442 0.1371  0.022 -0.0222 0.256 0.4903
> 0.0662 -0.0763 0.0064 0.1404
>
> *After running the code the "pylab.savetxt" saves the same data something
> like this*
>
>
> 8.205965840870644800e-01;8.034591567160346300e-01;5.493847743502982000e-01;2.581157685701491700e-01;6.409997826977161800e-01;3.719908502347885100e-01
>

I assume you are confused about the many decimals. Whenever floats are
processed by Python they are real floats, see here:
http://docs.python.org/release/2.5.2/tut/node16.html

To me, it looks as if you have truncated the lines, but otherwise there is
nothing wrong...

*When I tried to extract data and print them they look like this (totally
> different from the actual values!)*
>
> [ 0.18353712  0.30468928  0.16164556 ...,  0.98860032  0.49681098
>   0.77393306]
>

Yes, these are different numbers. But I assume you are comparing different
rows or columns?!



> *When I tried not using the "pylab.savetxt" function it gives an error
> like below:*
>
> ValueError: invalid literal for float():
> 0.0023,-0.0456,0.0419,0.094,0.0224,0.0365
>

This error message tells you that you are trying to save non-numeric data to
a file with that command.
Eg. this will cause the same error: scipy.savetxt('asdfasdf.dat',
'asdfasdf')

It is *VERY* hard to tell what you are doing since you don't provide exact
pieces of code.


> *Is there a specific way to handle signed decimal number? If so please
> suggest some changes.* And also I did try using the "array[]" to access
> individual comulns but I get an error saying the numpy.ndarray object not
> callable.
>

I must ask again? Have you played with the examples that I provided? You are
using the function in a wrong way (again, I can't tell for sure since you
don't provide code):

In order to acces the first row from a data array, you simply use data[0],
the first column is data.T[0].

*import matplotlib.pyplot as plt
> import pylab
> import scipy
> import numpy
> datafile1 = 'vet1.csv'
> data = pylab.rand(98760,6)
> pylab.savetxt(datafile1, data, delimiter=';')
> a1 = pylab.loadtxt(datafile1, comments='#', delimiter=';').T
> print 'loading', datafile1
> v1 = [0,1]
> v2 = [-2,2]*
> *plt.close('all')
> plt.figure()*
> *plt.ylim(v2)
> for i in range(2):
>     plt.plot(a1[i])*
> *plt.show()*
>
>  -Karthik
>


Please do provide all steps that cause problems, not just the results. It is
impossible to help you with assumptions and guesses :)

Best regards,
Daniel

*Hi Daniel, *
* *
*I used the code but there is small issue. I forgot to mention that my
values are signed and unsigned decimal values. *
*My values look like this
*
 0.0023 -0.0456 0.0419 0.094  -0.0004 0.0236 -0.0237 -0.0043  -0.0718 0.0095
0.0592 -0.0417  0.0023 0.0386 -0.0023 -0.0236  -0.1045 0.098 -0.0006 0.0516
0.0463 -0.0035 -0.0442 0.1371  0.022 -0.0222 0.256 0.4903  0.0662 -0.0763
0.0064 0.1404

*After running the code the "pylab.savetxt" saves the same data something
like this*


8.205965840870644800e-01;8.034591567160346300e-01;5.493847743502982000e-01;2.581157685701491700e-01;6.409997826977161800e-01;3.719908502347885100e-01

*When I tried to extract data and print them they look like this (totally
different from the actual values!)*

[ 0.18353712  0.30468928  0.16164556 ...,  0.98860032  0.49681098
  0.77393306]

*When I tried not using the "pylab.savetxt" function it gives an error like
below:*

ValueError: invalid literal for float():
0.0023,-0.0456,0.0419,0.094,0.0224,0.0365

*Is there a specific way to handle signed decimal number? If so please
suggest some changes.* And also I did try using the "array[]" to access
individual comulns but I get an error saying the numpy.ndarray object not
callable.

*import matplotlib.pyplot as plt
import pylab
import scipy
import numpy
datafile1 = 'vet1.csv'
data = pylab.rand(98760,6)
pylab.savetxt(datafile1, data, delimiter=';')
a1 = pylab.loadtxt(datafile1, comments='#', delimiter=';').T
print 'loading', datafile1
v1 = [0,1]
v2 = [-2,2]*
*plt.close('all')
plt.figure()*
*plt.ylim(v2)
for i in range(2):
    plt.plot(a1[i])*
*plt.show()*

 -Karthik

On Fri, Jun 10, 2011 at 12:50 PM, calmar c. <ma...@ca...> wrote:

> On Fri, Jun 10, 2011 at 11:10:02AM -0500, Benjamin Root wrote:
> >
> >    Why not just use an array of datetime.timedelta objects?� I believe
> >    matplotlib already supports this, does automatic formatting and even
> >    allows you to easily modify how the formatting is done.
>
> I was not able to figure out how it would support them
> (datetime.timedelta objects).  datetime.datetime objects only as
> far as I saw.
>
>
That's right, I forgot about that.  Usually, my data would have a starting
point anyway, and I just use timedeltas after that point.


> So I would have to create some artificial datetime + add the
> timedeltas (seconds) to it and providing that to the plot I guess,
> right?
>
>
You might be able to get away with using a datetime.time object and add
timedeltas.  The formatting should be what you would like to see.



> So far the solution to just show i.e. 70sec as 00:01:20 via some
> little function is almost more sympathetic to me (so far at least).
>
>
Whatever works best for you, that's more important.  Note that matplotlib
has some  special treatment of date, time and datetime objects to do extra
things for you.  It might be a bit tricky at first, but it becomes easier to
use later.

Admittedly, these following examples are for dates (and might even need to
be updated...)
http://matplotlib.sourceforge.net/examples/api/date_demo.html
http://matplotlib.sourceforge.net/examples/api/date_index_formatter.html

There are others as well.

Note that probably half that code can probably be removed for v1.0.x.  When
I did my graphs a few months ago, I don't recall needing to specify any
formatters.  Maybe I should dig up my code and update those examples.

Cheers,
Ben Root