The SCATDOT glyph creates a scatter dot plot of all of the x and y coordinates for the data referenced by the scatdot through the col1 and col2 column numbers/names in panelDesc data.frame structure that point to columns in the statsDFrame data.frame provide by the USER with the data. The data from each area row is repersented by a dot in the scatdot graphic. The areas highlighted in the current group/row are shown using slightly large dots and the color of their associated area in the group/row set. There may be from 3 to 5 areas represented in a single group/row set and link by color to the geographic area in the micromap drawn from the boundary data provided in the boundary group data.
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Jim Pearson, StatNet Consulting, LLC, Gaithersburg, MD
The only internal argument is j identifying the graphic column number being drawn. j is used by all of the panel functions to scale, outline, and select the area within the total graphic page to draw a column of the scatdot glyphs, one per group/row. It is also used to reference the panelDesc column to retreive related information and links to be able to draw and label the scatdot graphic and column. The scatdot glyph uses the col1 and col2 variable to identify the statsDFrame columns that contain the x and y coordinates for each dot representing an area. The lab1, lab2, lab3, and lab4 variables provide the header and trailing character strings for the column.
The graphic is a simple x-y plot of the data points provide to the scatdot routines.
The refval, reftxt, and panelData variable in the panelDesc structure are not used.
Scatdot glyph has the ability to add a "DIAGONAL" or "LOWESS" line to the graphic as an option. The default is a white diagonal line. The parm variable list in the panelDesc is used by the user to request the type of line, the color, R type, and R width. In the list for the glyph column, the user starts by specifying "LINE=" to request "NONLINE", "DIAGONAL" or a "LOWESS" based line (upper or lower case). If a "LOWESS" type line is desired, the f value for the LOWESS function is set with "f=<value>" in the parm list. The value must be a decimal number ranging from .01 to 100. The range is not checked. All f values may not work if to small or large. Check with the R documentation on the "LOWESS" function in the stats package. The user cannot change the "iter" parameter. It defaults to 3. If the "LOWESS" function parameters are not acceptable to R, the system may terminate the micromapST function call and report an error. The user can also specify the line color (line.col, any valid hex value or "R" color name), line width (line.lwd, range of .5 to 2 is reasonable, default is 0.5) or the "R" line type (line.lty, the default is "solid" or any of the "R" types.) There extra parameters are passed to the glyph code via the panelDesc "parm=list( )" variable. This is the only panelDesc variable that must be a list of lists. Because of the R language there are two ways to successfully add the parm list to micromapST package:
panelDesc <- data.frame(type = c("map","scatdot"),
lab1 = c("US", "population"),
lab2 = c(NA, "1920"),
col1 = c(NA, "x"),
col2 = c(NA, "y")
)
wparm <- list(NA, list(line="LOWESS",f=.77,line.col="blue",line.lwd=1,line.lty="solid"))
panelDesc$parm <- wparm
or
panelDesc <- data.frame(type = c("map","scatdot"),
lab1 = c("US", "population"),
lab2 = c(NA, "1920"),
col1 = c(NA, "x"),
col2 = c(NA, "y"),
parm = I(list(NA, list(line="LOWESS",f=.77,line.col="blue",line.lwd=1,line.lty="solid")))
)
In the second example, the "I()" function must be used around the list structure to make sure R does not parse the parm value when adding to the data.frame.
The resulting panelDesc structure should look like:
> str(panelDesc)
'data.frame': 2 obs. of 6 variables:
$ type: chr "map" "scatdot"
$ lab1: chr "US" "population"
$ lab2: chr NA "1920"
$ col1: chr NA "x"
$ col2: chr NA "y"
$ parm:List of 2
..$ : logi NA
..$ :List of 5
.. ..$ line : chr "LOWESS"
.. ..$ f : num 0.77
.. ..$ line.col: chr "blue"
.. ..$ line.lwd: num 1
.. ..$ line.lty: chr "solid"
..- attr(*, "class")= chr "AsIs"
>
For details on the lowess R function refer to the stats package documention and the lowess function.
This allows the user to customize these optiona for each scatdot glyphic column, as needed.
The defaults for the scatdot "parm list variable" are:
if "line='NOLINE'" There are no defaults.
if "line='DIAGONAL'" or "line='LOWESS'" then defaults are:
line.col = "white" or "gray20", respectfully
line.lwd = 0.5
line.lty = "solid"
if "line='LOWESS'" then
f = .666666
if the parameter list is empty or there is no "line=" parameter,
"line='DIAGONAL'" is assumed.
The user can change any of the scatdot options using in the parm row list entry.
The statsDFrame and panelDesc data.frames reside in the global environment and automatically accessible to the process along with several other major structures.
micromapST