The SIM2D Procedure

PROC SIM2D Statement

PROC SIM2D options;

The PROC SIM2D statement invokes the SIM2D procedure. Table 91.2 summarizes the options available in the PROC SIM2D statement.

Table 91.2: PROC SIM2D Statement Options

Option	Description
DATA=	Specifies an input data set
IDGLOBAL	Uses ascending observation numbers across BY groups
IDNUM	Uses the observation number for the observation labels
NARROW	Restricts the variables included in the OUTSIM= data set
NOPRINT	Suppresses the normal display of results
OUTSIM=	Writes simulated values to a SAS data set
PLOTS	Specifies plot display and options

You can specify the following options with the PROC SIM2D statement.

DATA=SAS-data-set

specifies a SAS data set that contains the x and y coordinate variables and the VAR= variables that are used in the SIMULATE statements. This data set is required if you specify the BY statement or the COORDINATES statement or if any of the SIMULATE statements are conditional—that is, if you specify the VAR= option in any of those. Otherwise, you do not need the DATA= option, and this option is ignored if you specify it.

IDGLOBAL

specifies that ascending observation numbers be used across BY groups for the observation labels in the appropriate output data sets and the OBSERVATIONS plot, instead of resetting the observation number in the beginning of each BY group. The IDGLOBAL option is ignored if no BY variables are specified. Also, if you specify the ID statement, then the IDGLOBAL option is ignored unless you also specify the IDNUM option in the PROC SIM2D statement.

IDNUM

specifies that the observation number be used for the observation labels in the appropriate output data sets and the OBSERVATIONS plot. The IDNUM option takes effect when you specify the ID statement; otherwise, it is ignored.

NARROW

restricts the variables included in the OUTSIM= data set. When you specify the NARROW option, only four variables are included. This option is useful when a large number of simulations are produced. Including only four variables reduces the memory required for the OUTSIM= data set. For details about the variables that are excluded with the NARROW option, see the section Output Data Set.

NOPRINT

suppresses the normal display of results. The NOPRINT option is useful when you want only to create one or more output data sets with the procedure. Note: This option temporarily disables the Output Delivery System (ODS); see the section ODS Graphics for more information.

OUTSIM=SAS-data-set

specifies a SAS data set in which to store the simulation values, iteration number, simulate statement label, variable name, and grid location. For details, see the section Output Data Set.

PLOTS <(global-plot-option)> <= plot-request<(options)>> PLOTS <(global-plot-option)> <= (plot-request<(options)> <... plot-request<(options)>>)>

controls the plots produced through ODS Graphics. When you specify only one plot request, you can omit the parentheses around the plot request. Here are some examples:

plots=none
plots=observ
plots=(observ(outl) sim)
plots=(sim(fill=mean line=sd obs=grad) sim(fill=sd))

ODS Graphics must be enabled before plots can be requested. For example:

ods graphics on;

proc sim2d data=thick outsim=sim;
   coordinates xc=East yc=North;
   simulate var=Thick numreal=5000 seed=79931
      scale=7.4599 range=30.1111 form=gauss;
   mean 40.1173;
   grid x=0 to 100 by 2.5 y=0 to 100 by 2.5;
run;

ods graphics off;

For more information about enabling and disabling ODS Graphics, see the section Enabling and Disabling ODS Graphics in Chapter 21: Statistical Graphics Using ODS.

By default, no graphs are created; you must specify the PLOTS= option to make graphs.

The following global-plot-option is available:

ONLY: produces only plots that are specifically requested.

The following individual plot-requests and plot options are available:

ALL

produces all appropriate plots. You can specify other options with ALL. For example, to request all appropriate plots and an additional simulation plot, specify PLOTS=(ALL SIM).

EQUATE

specifies that all appropriate plots be produced in a way in which the axes coordinates have equal size units.

NONE

suppresses all plots.

OBSERVATIONS <(observations-plot-options)> OBSERV <(observations-plot-options)> OBS <(observations-plot-options)>

produces the observed data plot in conditional simulations. Only one observations plot is created if you specify the OBSERVATIONS option more than once within a PLOTS option.

The OBSERVATIONS option has the following suboptions:

GRADIENT

specifies that observations be displayed as circles colored by the observed measurement.

LABEL < ( label-option ) >

labels the observations. The label is the ID variable if the ID statement is specified; otherwise, it is the observation number. The label-option can be one of the following:

EQ=number: specifies that labels show for any observation whose value is equal to the specified number.
MAX=number: specifies that labels show for observations with values smaller than or equal to the specified number.
MIN=number: specifies that labels show for observations with values equal to or greater than the specified number.

If you specify multiple instances of the OBSERVATIONS option and you specify the LABEL suboption in any of those, then the resulting observations plot displays the observations labels. If more than one label-option is specified in multiple LABEL suboptions, then the prevailing label-option in the resulting OBSERVATIONS plot emerges by adhering to the choosing order: MIN, MAX, EQ.

OUTLINE

specifies that observations be displayed as circles with a border but with a completely transparent fill.

OUTLINEGRADIENT

is the same as OBSERVATIONS(GRADIENT) except that a border is shown around each observation.

SHOWMISSING

specifies that observations with missing values be displayed in addition to the observations with nonmissing values. By default, missing values locations are not shown on the plot. If you specify multiple instances of the OBSERVATIONS option and you specify the SHOWMISSING suboption in any of those, then the resulting observations plot displays the observations with missing values.

If you omit any of the GRADIENT, OUTLINE, and OUTLINEGRADIENT suboptions, the OUTLINEGRADIENT is the default suboption. If you specify multiple instances of the OBSERVATIONS option or multiple suboptions for OBSERVATIONS, then the resulting observations plot honors the last specified GRADIENT, OUTLINE, or OUTLINEGRADIENT suboption.

SIMULATION <(sim-plot-options)> SIM <(sim-plot-options)>

specifies that simulation plots be produced. You can specify the SIM option multiple times in the same PLOTS option to request instances of plots with the following sim-plot-options:

ALPHA=number

specifies a parameter to obtain the confidence level for constructing confidence limits based on the simulation standard deviation. The value of number must be between 0 and 1, and the confidence level is $1-$ number. The default is ALPHA=0.05; this corresponds to the confidence level of 95%. The ALPHA= suboption is used only for simulation plots in one dimension, and it is incompatible with the FILL and LINE suboptions.

CLONLY

specifies that only the confidence limits be shown in a simulation plot without the simulation mean. This suboption can be useful for identifying confidence limits when the simulation standard deviation is small at the simulation locations. CLONLY is used only for simulation band plots of simulations on a linear grid, and it is incompatible with the FILL and LINE suboptions.

CONNP

specifies that grid points that you provide as individual simulation locations be connected with a line on the area map. This suboption is ignored when you have a single grid point, a prediction grid in two dimensions, or when you also specify the NOMAP suboption. The CONNP suboption is incompatible with the FILL and LINE suboptions.

FILL=NONE | MEAN | SD

produces a surface plot for either the values of the means or the standard deviations. FILL=SD is the default. However, if you omit the FILL suboption the behavior depends on the LINE suboption as follows: If you specify LINE=NONE or entirely omit the LINE suboption, then the FILL suboption is set to its default value. If LINE=PRED or LINE=SE, then the FILL suboption is set to the same value as the LINE suboption.

LINE=NONE | MEAN | SD

produces a contour line plot for either the values of the means or the standard deviations. LINE=MEAN is the default. However, if you omit the LINE suboption the behavior depends on the FILL suboption as follows: If you specify FILL=NONE or entirely omit the FILL suboption, then the LINE suboption is set to its default value. If FILL=PRED or FILL=SE, then the LINE suboption is set to the same value as the FILL suboption.

NOMAP

specifies that the simulation plot be produced without a map of the domain where you have observations. The NOMAP suboption is used in the case of simulation in one dimension or at individual points. It is ignored in the case of unconditional simulation, and it is incompatible with the FILL and LINE suboptions.

OBS=obs-options

produces an overlaid scatter plot of the observations in addition to the specified contour plots. The following obs-options are available:

GRAD: specifies that observations be displayed as circles colored by the observed measurement. The same color gradient displays the means surface and the observations. The conditional simulation honors the observed values, so the means surface at the observation locations has the same color as the corresponding observations.
LINEGRAD: is the same as OBS=GRAD except that a border is shown around each observation. This option is useful for identifying the location of observations where the standard deviations are small, because at these points the color of the observations and the color of the surface are indistinguishable.
NONE: specifies that no observations be displayed.
OUTL: specifies that observations be displayed as circles with a border but with a completely transparent fill.

OBS=NONE is the default when you have a grid in two dimensions, and OBS=LINEGRAD is the default used in the area map when you specify a conditional simulation in one dimension.

SHOWD

specifies that the horizontal axis in scatter plots of linear simulation grids show the distance between grid points instead of the grid points’ coordinates. When the area map is displayed, the simulation locations are also connected with a line. In all other grid configurations the SHOWD suboption is ignored, and it is incompatible with the FILL and LINE suboptions.

SHOWP

specifies that the grid points in band plots of linear simulation grids be shown as marks on the band plot. In all other grid configurations the SHOWP suboption is ignored, and it is incompatible with the FILL and LINE suboptions.

TYPE=BAND | BOX

requests a particular type of plot when you have a linear grid, regardless of the default SIM plot behavior in this case. The TYPE suboption is incompatible with the FILL and LINE suboptions.

If you specify multiple instances of the ALPHA, FILL, LINE, OBS, or TYPE suboptions in the same SIM option, then the resulting simulation plot honors the last value specified for any of the suboptions. Any combination where you specify FILL=NONE and LINE=NONE is not available. When the simulation grid is in two dimensions, only the FILL, LINE, and OBS suboptions apply. If you specify incompatible suboptions in the same SIM plot, then the plot instance is skipped.

The SIM option produces a surface or contour line plot for grids in two dimensions and a band plot or box plot for grids in one dimension or individual points. In two dimensions the plot illustrates the means and standard deviations of the simulation realizations at each grid point. By default, when you specify a linear grid with fewer than 10 points, PROC SIM2D produces a SIM box plot that depicts the simulation distribution at each point. For 10 or more points in a linear grid, the SIM plot is a band plot of the simulation means and the confidence limits at the 95% confidence level. You can override the default behavior in linear grids with the TYPE suboption. Simulation at individual locations always produces a SIM box plot.

In cases of conditional simulation in one dimension or at individual points an area map is produced that shows the observations and the grid points. Band plots of linear grids display the grid points as a line on the map. When you specify individual simulation locations, the grid points are indicated with marks on the area map. The area map appears on the side of conditional simulation band plots or box plots, unless you specify the NOMAP suboption. You can also label individual grid points or the ends of linear grid segments with the LABEL option of the GRID statement.

SEMIVARIOGRAM <(semivar-plot-option)> SEMIVAR <(semivar-plot-option)>

specifies that the semivariogram used for the simulation be produced. You can use the following semivar-plot-option:

MAXD=number: specifies a positive value for the upper limit of the semivariogram horizontal axis of distance. The SEMIVARIOGRAM plot extends by default to a distance that depends on the correlation model range. You can use the MAXD= option to adjust the default maximum distance value for the plot.

The SEMIVARIOGRAM option produces a plot for each correlation model that you specify for your simulation tasks. In an anisotropic case, the plot is not produced if you assign different anisotropy angles for different model components. The only exception is when you specify zonal components at right angles with the nonzonal model components. Also, the SEMIVARIOGRAM option is ignored for models that consist of purely zonal components.