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MathGroup Archive 2006

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Re: "Not a floating-point number" WHY?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg70463] Re: "Not a floating-point number" WHY?
  • From: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>
  • Date: Tue, 17 Oct 2006 02:58:26 -0400 (EDT)
  • Organization: The Open University, Milton Keynes, UK
  • References: <egvbr1$s16$1@smc.vnet.net>

Henning Heiberg-Andersen wrote:
>  Hi,
> 
> I have a hard time trying to understand why I get the floating-point error
> in this
> particular case: I dont't see what's wrong with the list I am trying to
> plot.
> Here it is:
> 
> 
> In[1]:=  small=Take[vec,2]
> 
> Out[1]:=  { {30.06, 23523}, {56. 38,00005}}
> 
> In[2]:=  ListPlot[small]
> 
> Then I get the error message:
> 
> Graphics::gptn : Coordinate 30.06 in {30.06, 23523} is not a floating-point
> number.
> 
> Hope someone can explain this to me.
> 
> Best regards,
> 
> Henning Heiberg-Andersen
> 
> 
Hi,

Looking at what you posted, I am confident that the values hold by vec 
are in string format. You can check that with Map[Head, small, {-1}]. 
Now you can transform the strings into expressions by using 
ToExpression, but beware that your data set seems odd: an entry such as 
00005 is going to be converted as 5. However, 56. 38 will become 2128. 
since the white space is going to be interpreted as implicit multiplication.

In[1]:=
small={{"30.06","23523"},{"56. 38","00005"}}

Out[1]=
{{30.06,23523},{56. 38,00005}}

In[2]:=
ListPlot[small];

 From In[2]:=
Graphics::"gptn":"Coordinate 30.06 in {30.06, 23523} is not a 
floating-point number.

In[3]:=
Map[Head,small,{-1}]

Out[3]=
{{String,String},{String,String}}

In[4]:=
small=ToExpression[small]

Out[4]=
{{30.06,23523},{2128.,5}}

In[5]:=
Map[Head,small,{-1}]

Out[5]=
{{Real,Integer},{Real,Integer}}

In[6]:=
ListPlot[small];

Regards,
Jean-Marc


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