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Re: How do I manipulate that data?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg22457] Re: How do I manipulate that data?
  • From: "Allan Hayes" <hay at haystack.demon.co.uk>
  • Date: Sun, 5 Mar 2000 00:23:51 -0500 (EST)
  • References: <89iaoe$msi@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

Mark,

My tmp file looks like

!! tmp

0.341719   0.990566

0.505954   0.28635

0.663925   0.309206

Read it in, as you do,

data = ReadList["tmp", {Real, Real}]

{{0.341719, 0.990566}, {0.505954, 0.28635}, {0.663925, 0.309206}}

Square the second entry in each row

data /. {{x_Real, y_Real} :> {x, y^2}}

{{0.341719, 0.981221}, {0.505954, 0.0819963}, {0.663925, 0.0956084}}

It's probably better to get the raw data in this case, but we can use

ReadList["tmp", Unevaluated[{#1, #2^2} &[Real, Real]]]

{{0.341719, 0.981221}, {0.505954, 0.0819963}, {0.663925, 0.0956084}}


Allan
---------------------
Allan Hayes
Mathematica Training and Consulting
Leicester UK
www.haystack.demon.co.uk
hay at haystack.demon.co.uk
Voice: +44 (0)116 271 4198
Fax: +44 (0)870 164 0565

"mark griggs" <markgriggs at sc.rr.com> wrote in message
news:89iaoe$msi at smc.vnet.net...
> Hello all,
>   I have a data file called data.txt.  It consists of 2 columns of
> data.  I am able to read with
> data = ReadList["/home/mark/data.txt", {Real, Real}];   I let the first
> column represent x and the second represent y.  Then I plot y vs. x
> with   ListPlot[data].    My problem is that I need to plot y^2 vs. x.
> So, how can I square all the y terms?
>
> regards
>
> mark
>
>
>
>
> --
> Heisenburg may have slept here
> ------------------------------
>
>
>



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