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I have file structured as (Axis 1) (Axis 2) Data.
As an example:

1.2E-003 -0.500        0.0000000000000000     
1.2E-003 -0.493       1.53468784818295775E-004
1.2E-003 -0.487       5.89210645476378352E-004
1.2E-003 -0.481       1.23713800962565101E-003
1.2E-003 -0.475       1.99285240196946144E-003

2.8E-003 -0.500        0.0000000000000000     
2.8E-003 -0.493       1.65202052327590321E-004
2.8E-003 -0.487       6.34230407238311057E-004
2.8E-003 -0.481       1.33156043724947304E-003
2.8E-003 -0.475       2.14469618088317755E-003

In other words:

  • Each line has 3 real values
  • The data is divided in blocks separated by a blank line.
    • The size of each block is between 200 and 3000 (this size is unknown prior to reading the file, but I could write a shell script to extract and store this information somewhere if that makes things easier).
    • The first value is the same for the entire block.
  • There are exactly 1000 blocks.

I would like Mathematica to open this file and store this information inside a variable. This variable would be a list of vectors.

In this list, each element (a vector) corresponds to 1 block, and this vector contains the data from the third column (all other data is discarded).

In this example, the variable should be a list of 2 vectors:

{{ 0.0000000000000000 , 1.53468784818295775E-004 , 5.89210645476378352E-004 , 1.23713800962565101E-003 , 1.99285240196946144E-003 },
 { 0.0000000000000000 , 1.65202052327590321E-004 , 6.34230407238311057E-004 , 1.33156043724947304E-003 , 2.14469618088317755E-003 }}

Is this easy to do?

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Yes, please have a look at Import. –  b.gatessucks Mar 4 '13 at 13:07
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closed as too localized by Ajasja, rcollyer, Yves Klett, acl, m_goldberg Mar 4 '13 at 19:14

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1 Answer

up vote 4 down vote accepted


ReadList["file.dat", {Number, Number, Number}] ~SplitBy~ First


SplitBy[Import["file.dat", "Table"], # === {} &] ~DeleteCases~ {{}}
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You can then use Part to get what you want. –  Mr.Wizard Mar 4 '13 at 16:05
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