Chapters: 1: Introduction 2: Simple example 3: Invocation 4: Finer Control 5: X-Y Plots 6: Contour Plots 7: Image Plots 8: Examples 9: Gri Commands 10: Programming 11: Environment 12: Emacs Mode 13: History 14: Installation 15: Gri Bugs 16: Test Suite 17: Gri in Press 18: Acknowledgments 19: License Indices: Concepts Commands Variables | ### 9.3.15: ``heal`'
    heal columns|{columns along x|y}
- The ``heal`' command heals over gaps in either columnar or gridded data. This is done by linear interpolation across the missing-value gaps. ``heal columns`' Fill in missing values in x, y, z, ... columns, by linear interpolation to neighboring valid data. All gaps in the data will get replaced by a linear function of index which matches the data at the indices just before and just after the gap. For example, if the y data were like
      111
      3
      -9
      -9
      -9
      7
      333
  where ``-9`' is the missing-value code, then they would get replace by
      111
      3
      4
      5
      6
      7
      333
Notes: (1) This is done independently for all existing columns. (2) Gaps at the start and end of the columns are not filled in. ``heal grid along x`' Scan in the x direction, filling in missing values by linear interpolation. Since this uses the the x-grid, you must first have done ``read grid x`' or ``set x grid`'. ``heal grid along y`' Scan in the y direction, filling in missing values by linear interpolation. Since this uses the the y-grid, you must first have done ``read grid y`' or ``set y grid`'.