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

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`'.