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I have a text file where each line is a data point in the form:

[ -495.01172, -158.35966, 2705.0 ]
[ -489.15576, -127.229675, 2673.0 ]
[ -487.6918, -97.679855, 2665.0 ]
[ -487.32578, -68.4594, 2663.0 ]
[ -485.86182, -39.19415, 2655.0 ]
[ -485.3128, -10.12311, 2652.0 ]
[ -484.03183, 18.853745, 2645.0 ]
[ -482.75082, 47.677364, 2638.0 ]
[ -481.6528, 76.37677, 2632.0 ]
[ -481.6528, 105.184616, 2632.0 ]
...

Each line represents [x,y,z]. I need to 3D plot these, but I am getting errors. Below is what I've tried along with the resulting error.

data = Import[
  "C:\\Users\\user\\Desktop\\out.txt", "text"]

data2 = List[
  StringReplace[
   data, {"[" -> "{", "]" -> "}", "\n" -> ",", " " -> ""}]]

ListPointPlot3D[data2]

The first two lines run successfully. The last line returns:

...{1161.5232,-887.44867,1677.0}} must be a valid array or a list of valid arrays >>
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  • $\begingroup$ "I have a text file..." - post it on Pastebin, please. $\endgroup$
    – J. M.'s missing motivation ♦
    Commented Nov 8, 2017 at 19:14
  • $\begingroup$ @J.M. Why? Is the sample I've provided not enough? Or are you wanting to see it in a specific format? The format I've shown above is the same for every row. $\endgroup$
    – whatwhatwhat
    Commented Nov 8, 2017 at 19:16
  • $\begingroup$ Either way, Pastebin says I can't paste that much data. $\endgroup$
    – whatwhatwhat
    Commented Nov 8, 2017 at 19:16
  • $\begingroup$ I suspect that your problem is in how you import your file, and possibly something wonky within your file. $\endgroup$
    – J. M.'s missing motivation ♦
    Commented Nov 8, 2017 at 19:17
  • 1
    $\begingroup$ ToExpression should be used somewhere to convert the string in a mathematica expression $\endgroup$
    – andre314
    Commented Nov 8, 2017 at 19:25

3 Answers 3

Reset to default
4
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This works, but may be there is easier way

SetDirectory[NotebookDirectory[]]
data  = Flatten@Import["input.txt","CSV"];
data2 = If[StringQ[#],ToExpression[StringDelete[#,{"[","]"}]],#]&/@data;
data2 = ArrayReshape[data2,{Length@data2/3,3}]

now

MatrixForm[data2]

Mathematica graphics

Plot it

ListPointPlot3D[data2]

Mathematica graphics

The input file is what was shown in OP

Mathematica graphics

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1
  • $\begingroup$ This worked fine, thanks $\endgroup$
    – whatwhatwhat
    Commented Nov 8, 2017 at 21:01
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I copied the 10 lines in your question and pasted them into a text file called out.txt.

data = Import["D:\\at_work\\mathematica\\stack_exchange\out.txt", 
  "text"]

The basic problem with the way you were working is that what appears to be numbers are strings and you have to convert them.

I did that as follows. First I split them into separate lines.

dataN = StringSplit[data, EndOfLine]

This produces a list of strings of the form you indicated for each line, one per line.

Now I used StringCases on each of these lines converting the strings to numbers.

data2 = Map[
  StringCases[#, 
    "[" ~~ Whitespace ~~ x__ ~~ "," ~~ Whitespace ~~ y__ ~~ "," ~~ 
      Whitespace ~~ z__ ~~ Whitespace ~~ "]" :> 
     Sequence[ToExpression[x], ToExpression[y], ToExpression[z]]] &,
  dataN
  ]

(* {{-495.012, -158.36, 2705.}, {-489.156, -127.23, 
  2673.}, {-487.692, -97.6799, 2665.}, {-487.326, -68.4594, 
  2663.}, {-485.862, -39.1942, 2655.}, {-485.313, -10.1231, 
  2652.}, {-484.032, 18.8537, 2645.}, {-482.751, 47.6774, 
  2638.}, {-481.653, 76.3768, 2632.}, {-481.653, 105.185, 2632.}} *)

The output is a list of lists with three real numbers in each sub-list.

ListPlot3D[data2]

Mathematica graphics

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2
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another approach.

ImportString[
 StringReplace[
  Import["test.txt", "Text"], {"[", "]"} -> ""], "CSV"]
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