I am trying to read some numbers that are in scientific notation out of a string.

An example string is:

# Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m

where I need to read out:

0
-2e-06
1e-06

I have not been able to find a way to do this. I have played with textscan and regexp but no luck. Maybe someone has an idea?

Thanks,
--
Mike

Mike wrote:
> I am trying to read some numbers that are in scientific notation out of 
> a string.
> 
> An example string is:
> 
> # Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m
> 
> where I need to read out:
> 
> 0
> -2e-06
> 1e-06
> 
> I have not been able to find a way to do this. I have played with 
> textscan and regexp but no luck. Maybe someone has an idea?

Try a scan format of '%*[^=]%*[=]%f%*[m]'

Walter Roberson <roberson@hushmail.com> wrote in message <Ari4o.4420$mW5.1426@newsfe14.iad>...
> Mike wrote:
> > I am trying to read some numbers that are in scientific notation out of 
> > a string.
> > 
> > An example string is:
> > 
> > # Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m
> > 
> > where I need to read out:
> > 
> > 0
> > -2e-06
> > 1e-06
> > 
> > I have not been able to find a way to do this. I have played with 
> > textscan and regexp but no luck. Maybe someone has an idea?
> 
> Try a scan format of '%*[^=]%*[=]%f%*[m]'

I tried doing textscan(line, '%*[^=]%*[=]%f%*[m]') and I get an output of

ans = [3x1 double]

not sure what the issue is and I also don't understand what your format is saying/doing?

"Mike " <mikejcunningham@gmail.com> wrote in message <i2saca$74c$1@fred.mathworks.com>...
> I am trying to read some numbers that are in scientific notation out of a string.
> 
> An example string is:
> 
> # Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m
> 
> where I need to read out:
> 
> 0
> -2e-06
> 1e-06
> 
> I have not been able to find a way to do this. I have played with textscan and regexp but no luck. Maybe someone has an idea?
> 
> Thanks,
> --
> Mike

one of the many solutions
- based on the above format

     s='# Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m';
     r=regexp(s,'(?<== )((-)|(\d+)|(e))+','match');
     r=sscanf(sprintf('%s ',r{:}),'%g')
%{
%    r =
          0
          -2e-006
          1e-006
%}

us

"Mike " <mikejcunningham@gmail.com> wrote in message <i2sd0o$eo$1@fred.mathworks.com>...
> Walter Roberson <roberson@hushmail.com> wrote in message <Ari4o.4420$mW5.1426@newsfe14.iad>...
> > Mike wrote:
> > > I am trying to read some numbers that are in scientific notation out of 
> > > a string.
> > > 
> > > An example string is:
> > > 
> > > # Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m
> > > 
> > > where I need to read out:
> > > 
> > > 0
> > > -2e-06
> > > 1e-06
> > > 
> > > I have not been able to find a way to do this. I have played with 
> > > textscan and regexp but no luck. Maybe someone has an idea?
> > 
> > Try a scan format of '%*[^=]%*[=]%f%*[m]'
> 
> I tried doing textscan(line, '%*[^=]%*[=]%f%*[m]') and I get an output of
> 
> ans = [3x1 double]
> 
> not sure what the issue is and I also don't understand what your format is saying/doing?

well... you're just using

one of the other solutions

     s='# Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m';
     r=textscan(s,'%*[^=]%*[=]%f%*[m]');
     r=[r{:}]
%{
%    r =
          0
          -2e-006
          1e-006
%}

us

Mike wrote:
> Walter Roberson <roberson@hushmail.com> wrote in message 
> <Ari4o.4420$mW5.1426@newsfe14.iad>...
>> Mike wrote:
>> > I am trying to read some numbers that are in scientific notation out 
>> of > a string.
>> > > An example string is:
>> > > # Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m
>> > > where I need to read out:
>> > > 0
>> > -2e-06
>> > 1e-06
>> > > I have not been able to find a way to do this. I have played with 
>> > textscan and regexp but no luck. Maybe someone has an idea?
>>
>> Try a scan format of '%*[^=]%*[=]%f%*[m]'
> 
> I tried doing textscan(line, '%*[^=]%*[=]%f%*[m]') and I get an output of
> 
> ans = [3x1 double]
> 
> not sure what the issue is and I also don't understand what your format 
> is saying/doing?

As Urs indicated, you just need to de-reference the cell that textscan produces.

%*[^=]

means to scan for a class of characters (the %[] part), where the class of 
characters is everything _except_ (the ^ part) the equal-sign (the = part), 
and then to throw the scanned value away (the * part).

%*[=] means to scan for equal signs and to throw the scanned value away.

Between these two, you scan up to and including the = and discard that part.

The %f reads a floating point number. Because there is no * the result is 
retained.

The %*[m] scans for 'm' and discards it.


Now that I'm at my desk I have confirmed that you can do the same thing with

%*[^=]=%fm

as literal characters are automatically discarded when matched.

Walter Roberson <roberson@hushmail.com> wrote in message <i2sg53$s83$1@canopus.cc.umanitoba.ca>...
> Mike wrote:
> > Walter Roberson <roberson@hushmail.com> wrote in message 
> > <Ari4o.4420$mW5.1426@newsfe14.iad>...
> >> Mike wrote:
> >> > I am trying to read some numbers that are in scientific notation out 
> >> of > a string.
> >> > > An example string is:
> >> > > # Beam sigy = 0 m, muy = -2e-06 m, dy = 1e-06 m
> >> > > where I need to read out:
> >> > > 0
> >> > -2e-06
> >> > 1e-06
> >> > > I have not been able to find a way to do this. I have played with 
> >> > textscan and regexp but no luck. Maybe someone has an idea?
> >>
> >> Try a scan format of '%*[^=]%*[=]%f%*[m]'
> > 
> > I tried doing textscan(line, '%*[^=]%*[=]%f%*[m]') and I get an output of
> > 
> > ans = [3x1 double]
> > 
> > not sure what the issue is and I also don't understand what your format 
> > is saying/doing?
> 
> As Urs indicated, you just need to de-reference the cell that textscan produces.
> 
> %*[^=]
> 
> means to scan for a class of characters (the %[] part), where the class of 
> characters is everything _except_ (the ^ part) the equal-sign (the = part), 
> and then to throw the scanned value away (the * part).
> 
> %*[=] means to scan for equal signs and to throw the scanned value away.
> 
> Between these two, you scan up to and including the = and discard that part.
> 
> The %f reads a floating point number. Because there is no * the result is 
> retained.
> 
> The %*[m] scans for 'm' and discards it.
> 
> 
> Now that I'm at my desk I have confirmed that you can do the same thing with
> 
> %*[^=]=%fm
> 
> as literal characters are automatically discarded when matched.

Ok thanks guys. US's suggestion worked. I tried to get the other but didn't succeed. Thank though.

So using US's method I can read in a line that looks like:

# Beam sigy = 0 m, muy = -1e-05 m, dy = 1e-06 m

However, something I didn't realise at the time, some files have the string looking like:

# Beam sigy = 0 m, muy = -0.000396 m, dy = 1e-06 m
OR
# Beam sigy = 0 m, muy = -5.6e-05 m, dy = 1e-06 m

For the first it will return -0 for the middle number
and 
for the 2nd it will return -5 and leave for the middle number.

I'm using 

                    r=regexp(line,'(?<== )((-)|(\d+)|(e))+','match')
                    r=sscanf(sprintf('%s ',r{:}),'%g');

is there a way to make it able to read these 3 formats?

Thanks again,
--
Mike

Mike wrote:
> So using US's method I can read in a line that looks like:
> 
> # Beam sigy = 0 m, muy = -1e-05 m, dy = 1e-06 m
> 
> However, something I didn't realise at the time, some files have the 
> string looking like:
> 
> # Beam sigy = 0 m, muy = -0.000396 m, dy = 1e-06 m
> OR
> # Beam sigy = 0 m, muy = -5.6e-05 m, dy = 1e-06 m
> 
> For the first it will return -0 for the middle number
> and for the 2nd it will return -5 and leave for the middle number.
> 
> I'm using
>                    r=regexp(line,'(?<== )((-)|(\d+)|(e))+','match')
>                    r=sscanf(sprintf('%s ',r{:}),'%g');
> 
> is there a way to make it able to read these 3 formats?

 >> t = textscan('# Beam sigy = 0 m, muy = -0.000396 m, dy = 1e-06 m', 
'%*[^=]=%fm',3);t{1}
ans =
                          0
                  -0.000396
                      1e-06
 >> t = textscan('# Beam sigy = 0 m, muy = -5.6e-05 m, dy = 1e-06 m', 
'%*[^=]=%fm',3);t{1}
ans =
                          0
                   -5.6e-05
                      1e-06


Getting a proper regexp format for scientific numbers is tricky.

"Mike " <mikejcunningham@gmail.com> wrote in message <i2smpp$h7k$1@fred.mathworks.com>...
> So using US's method I can read in a line that looks like:
> 
> # Beam sigy = 0 m, muy = -1e-05 m, dy = 1e-06 m
> 
> However, something I didn't realise at the time, some files have the string looking like:
> 
> # Beam sigy = 0 m, muy = -0.000396 m, dy = 1e-06 m
> OR
> # Beam sigy = 0 m, muy = -5.6e-05 m, dy = 1e-06 m
> 
> For the first it will return -0 for the middle number
> and 
> for the 2nd it will return -5 and leave for the middle number.
> 
> I'm using 
> 
>                     r=regexp(line,'(?<== )((-)|(\d+)|(e))+','match')
>                     r=sscanf(sprintf('%s ',r{:}),'%g');
> 
> is there a way to make it able to read these 3 formats?
> 
> Thanks again,
> --
> Mike

of course...

one of the many solutions

     s='# Beam sigy = 0 m, muy = -5.6e-05 m, dy = 1e-06 m';
     r=regexp(s,'(?<== )((\d)|(-)|(\.)|(e))+','match');
     r=sscanf(sprintf('%s ',r{:}),'%g')
%{
%    r =
          0
          -5.6e-005
          1e-006
%}

us

"us " <us@neurol.unizh.ch> wrote in message <i2ugq1$ajb$1@fred.mathworks.com>...
> "Mike " <mikejcunningham@gmail.com> wrote in message <i2smpp$h7k$1@fred.mathworks.com>...
> > So using US's method I can read in a line that looks like:
> > 
> > # Beam sigy = 0 m, muy = -1e-05 m, dy = 1e-06 m
> > 
> > However, something I didn't realise at the time, some files have the string looking like:
> > 
> > # Beam sigy = 0 m, muy = -0.000396 m, dy = 1e-06 m
> > OR
> > # Beam sigy = 0 m, muy = -5.6e-05 m, dy = 1e-06 m
> > 
> > For the first it will return -0 for the middle number
> > and 
> > for the 2nd it will return -5 and leave for the middle number.
> > 
> > I'm using 
> > 
> >                     r=regexp(line,'(?<== )((-)|(\d+)|(e))+','match')
> >                     r=sscanf(sprintf('%s ',r{:}),'%g');
> > 
> > is there a way to make it able to read these 3 formats?
> > 
> > Thanks again,
> > --
> > Mike
> 
> of course...
> 
> one of the many solutions
> 
>      s='# Beam sigy = 0 m, muy = -5.6e-05 m, dy = 1e-06 m';
>      r=regexp(s,'(?<== )((\d)|(-)|(\.)|(e))+','match');
>      r=sscanf(sprintf('%s ',r{:}),'%g')
> %{
> %    r =
>           0
>           -5.6e-005
>           1e-006
> %}
> 
> us

Thanks a lot of the help guys. Works great.