I'm trying to import data from the output of an old nuclear physics code. The data is tally results of particles crossing particular geometric cells. The output is generated with a great deal of extraneous information and no end of line delimiters. The information I want is generated in a 3 line form. I've bolded the information I'm looking to extract in the following example:

cell (1<6[5 5 0]<10[1 1 0]<9)
multiplier bin: -1.00000E+00 1 -6
0.00000E+00 0.0000

I can extract the cell information using:

a = FindList["input.txt", "1<", RecordSeparators -> {{"cell ("}, {")"}}]

However, I can't figure out to extract the second part. Is there a way to use string matching based on the fact that it will always be 6-digit scientific notation number followed by a single space then a 5 digit (<1) uncertainty?

EDIT: This scientific number will not always be zero. I should have written it more generally as X.XXXXXE+XX 0.YYYY where X and Y are any arbitrary value. (Even the plus sign is not constant for some values the value will be X.XXXXXE-XX 0.YYYY)

EDIT: To provide some more information on the output: The code is calculating the particle flux through a series of cells inside nested lattices. I'm currently working in a 11x11 lattice nested into a 5x5 lattice. Thus the full output would consists of 3025 versions of those 3 lines each with unique cell identifier varying from (1<6[-5:5 -5:5 0]<10[-2:2 -2:2 0]<9) and whatever the particle flux is in each cell as the numeric value in scientific notation. The "multiplier bin:..." line is a constant that multiplies the flux and will never change.

  • $\begingroup$ @george2079 I am not sure that your post-editing had clarified what OP want from the edited output... :(( $\endgroup$ Dec 18, 2017 at 19:24
  • $\begingroup$ maybe useful if you showed more of the file. Are those asterisks in there? $\endgroup$
    – george2079
    Dec 18, 2017 at 19:25
  • $\begingroup$ The asterisks are how the site bolded the text. When it was edited, the bolding disappeared and the asterisks appeared. $\endgroup$
    – T. Cardew
    Dec 18, 2017 at 19:26
  • $\begingroup$ oh i see, i fixed the edit. I guess we cant do formatting inside a code block. (sorry bout that) $\endgroup$
    – george2079
    Dec 18, 2017 at 19:29
  • $\begingroup$ can you clarify what you mean by no end of line delimiters. (how do you have blocks of 3 lines with no delimiters?) $\endgroup$
    – george2079
    Dec 18, 2017 at 19:50

2 Answers 2


probably best to do something like this:

lines = Import[file, "Lines"];
cells = Flatten@
  Position[lines, s_String /; StringMatchQ[s, "cell (" ~~ __ ~~ ")"]]

(* indices where each cell starts *)

then extract data from the ith cell like:

ImportString[lines[[cells[[i]] + 2]], "Table"]

{ 0.,0.}

  • $\begingroup$ Thank you. I was able to get it working based off of this suggestion but I had to use StringContainsQ not StringMatchQ. I'm not sure why. $\endgroup$
    – T. Cardew
    Dec 18, 2017 at 22:51
  • $\begingroup$ there may be a blank at the end of the line or something like that. $\endgroup$
    – george2079
    Dec 18, 2017 at 23:50

You can Import the file and store all the words in a list to extract (and convert) those you want:


(*  {"cell", "1<6[5", "5", "0]<10[1", "1", "0", "9", "multiplier", "bin", \
     "1.00000E+00", "1", "-6", "0.00000E+00", "0.0000"}  

As you have solved the first part, for the second one:

ToExpression@Take[TextWords[Import["input.txt"]], -2]

(* {0.,0.}  *)

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