Current Page: NeXtMidas Training Common Midas Concepts Blue Files Trimmers
- - | File Trimmers: File trimmers allow only a portion of a file to be read in. When a file trimmer is used the file looks (to the primitive) as if the file has been "trimmed" to a smaller size. The "trimming" is done internal to the Midas framework without modifying the file. File trimmers are specified by appending them to the end of a file name but before any qualifiers. For example:
        myfile.prm(<start>:<end>)
    - In the above example `<start>` is the start position in the file and `<end>` is the end position in the file. The start/end position can be one of the following:
      blank | Use the actual start/end of the file. | `myfile.prm(:<end>) myfile.prm(<start>:)`
      N | The absolute index (N) into the file. | `myfile.prm(N:<end>) myfile.prm(<start>:N)`
      -N | Start/end N elements before the end of the file. | `myfile.prm(-N:<end>) myfile.prm(<start>:-N)`
      ~N | Start/end at abscissa value N. | `myfile.prm(~N:<end>) myfile.prm(<start>:~N)`
  - Qualifiers and trimmers can be used at the same time, with trimmers followed by qualifiers. For example:
        X-Midas:   myfile.prm(10:51)(AUX=0)
        NeXtMidas: myfile.prm(9:50){AUX=CWD}
Some details of this will vary between Midas frameworks (especially 0-based vs 1-based indexing into a file).
Don't Make This Mistake:
Note: Trimmers must be defined first, then qualifiers.