Re: [Matplotlib-users] Not able to access CSV file:

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