New Features and Enhancements in version 5.5
New Features and Enhancements
The modulo length of an axis defined on the Ferret command line is set with an argument to the MODULO qualifier. Here is an example showing an axis defined explicitly as a modulo axis, and another which is modulo by default.
yes? DEFINE AXIS/MODULO=100/x=41:55:1 xax_subspan yes? DEFINE AXIS/X=100:300:10/UNITS=degrees_longitude xax_lonspan
The output of SHOW AXIS reflects this:
yes? show axis xax* name axis # pts start end XAX_SUBSPAN 6mr 41 46 Axis span (to cell edges) = 6 (modulo length = 100) XAX_LONSPAN LONGITUDE 21mr 100E 60W Axis span (to cell edges) = 210 (modulo length = 360)
In the NetCDF files you will now sometimes see the modulo attribute taking a value. Continuing the example above,
yes? LET v1 = X[GX=xax_subspan] +10 yes? let v2 = SIN(X[GX=xax_lonspan]) yes? SAVE/FILE=test_subspan_modulo.nc v1, v2 yes? SPAWN ncdump test_subspan_modulo.nc ... variables: double XAX_SUBSPAN(XAX_SUBSPAN) ; XAX_SUBSPAN:modulo = 100. ; ... double XAX_LONSPAN(XAX_LONSPAN) ; XAX_LONSPAN:modulo = 360. ;
The importance of the sub-span modulo axes is to take the first of two steps that will make it possible for users largely to ignore differences in encodings of longitude and climatological time -- e.g. the blending of data in plots and analyses where the data come from data sets that are encoded variously as -180:180, 0:360, etc. Thus, for example, in V5.5 you can refer to my_subspan_var[g=another_var] and get a meaningful answer as long as the grids occupy the same region on the globe, regardless of longitude encoding. (The second step, for a future release, will address the longitude encoding of scattered data.)
There is an implied void point in a sub-span modulo axis that fills the gap between the end of the axis and the start of the next modulo cycle. The data value at this point will always be the missing value flag (except for pseudo-variables such as "X[g=my_subspan_axis]"). Transformations such as smoothers do not operate across the void point.
yes? CANCEL MODE logo ! turns off the 3-line Ferret logo for subsequent plots yes? CANCEL MODE labels ! implements PLOT/NOLABEL for subsequent plots.
> Fprint -C -o my_file.ps metafile.pltNote that you will also want to choose a palette that is designed for CMYK output. See the FAQ "How can I get CMYK format for postscript files? " for a list of CMYK-friendly palettes, and for a description of the steps needed to create your own CMYK palettes.
yes? USE coads_climatology yes? CONTOUR/L=1/LEV=30 sst yes? SHOW SYM LEV* LEV_TEXT = "30" LEV_MIN = "-2" LEV_MAX = "32" LEV_NUM = "35" LEV_DEL = "1" yes? SHADE/L=5/LEV=(($LEV_MIN), ($LEV_MAX), 2) sst yes? SHOW SYM LEV* LEV_TEXT = "(-2, 32, 2)" LEV_MIN = "-2" LEV_MAX = "32" LEV_NUM = "18" LEV_DEL = "2"
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