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Translate a registry layer style to tmap v4 arguments

Source: R/gq_tmap_style.R
gq_tmap_style.Rd

Wraps gq_style() and returns a named list of arguments suitable for tmap v4 layer functions (tm_polygons, tm_lines, tm_dots, tm_symbols). Handles both simple and classified layers.

Usage

gq_tmap_style(layer_or_reg, name = NULL, field = NULL)

Arguments

layer_or_reg

Either a layer entry from the registry (e.g., reg$layers$lake) or a full registry list when using name-based lookup.

name

Optional layer name for name-based lookup. Accepts name_qgis_snake (e.g., "lake") or name_qgis (e.g., "Crossings - PSCIS assessment"). Normalized to match registry keys.

field

Optional character string to override the classification field name. Useful when data comes from an alternative source with a different column name (e.g., bcfishpass barrier_status vs WHSE barrier_result_code). See inst/registry/xref_layers.csv for known alternatives.

Value

A named list of tmap arguments. Use with do.call().

For a classified layer every aesthetic the registry defines is mapped per class, not just colour: line lwd and lty, point size. Each is returned as the classification field name plus a matching .scale, the same shape fill/col already used, so do.call() callers need no change. Numeric axes (lwd, size) fall back to a scalar when the registry defines the value for only some classes, since a half-mapped axis would invent a size for the gaps.

Examples

path <- system.file("examples", "mini_registry.json", package = "gq")
reg <- gq_registry_read(path)

# Name-based lookup
gq_tmap_style(reg, "lake")
#> $fill
#> [1] "#c6ddf0"
#> 
#> $fill_alpha
#> [1] 0.85
#> 
#> $col
#> [1] "#7ba7cc"
#> 
#> $lwd
#> [1] 0.5
#> 
gq_tmap_style(reg, "stream")
#> $col
#> [1] "#7ba7cc"
#> 
#> $lwd
#> [1] 0.4
#> 
#> $col_alpha
#> [1] 0.8
#> 
gq_tmap_style(reg, "road")
#> $col
#> [1] "road_type"
#> 
#> $col.scale
#> $FUN
#> [1] "tmapScaleCategorical"
#> 
#> $n.max
#> [1] 30
#> 
#> $values
#>   highway  arterial 
#> "#c0392b" "#e67e22" 
#> 
#> $values.repeat
#> [1] TRUE
#> 
#> $values.range
#> [1] NA
#> 
#> $values.scale
#> [1] NA
#> 
#> $value.na
#> [1] NA
#> 
#> $value.null
#> [1] NA
#> 
#> $value.neutral
#> [1] NA
#> 
#> $levels
#> [1] "highway"  "arterial"
#> 
#> $levels.drop
#> [1] TRUE
#> 
#> $labels
#> [1] "Highway"  "Arterial"
#> 
#> $label.na
#> [1] NA
#> 
#> $label.null
#> [1] NA
#> 
#> $label.format
#> list()
#> 
#> attr(,"class")
#> [1] "tm_scale_categorical" "tm_scale"             "list"                
#> 
#> $col.legend
#> $show
#> [1] FALSE
#> 
#> $called
#> [1] "show"
#> 
#> $title
#> [1] NA
#> 
#> $xlab
#> [1] NA
#> 
#> $ylab
#> [1] NA
#> 
#> $group_id
#> [1] NA
#> 
#> $group_type
#> [1] "tm_legend"
#> 
#> $z
#> [1] NA
#> 
#> attr(,"class")
#> [1] "tm_legend"    "tm_component" "list"        
#> 
#> $lwd
#> [1] "road_type"
#> 
#> $lwd.scale
#> $FUN
#> [1] "tmapScaleCategorical"
#> 
#> $n.max
#> [1] 30
#> 
#> $values
#> [1] 2.0 1.5
#> 
#> $values.repeat
#> [1] TRUE
#> 
#> $values.range
#> [1] NA
#> 
#> $values.scale
#> [1] NA
#> 
#> $value.na
#> [1] NA
#> 
#> $value.null
#> [1] NA
#> 
#> $value.neutral
#> [1] NA
#> 
#> $levels
#> [1] "highway"  "arterial"
#> 
#> $levels.drop
#> [1] TRUE
#> 
#> $labels
#> NULL
#> 
#> $label.na
#> [1] NA
#> 
#> $label.null
#> [1] NA
#> 
#> $label.format
#> list()
#> 
#> attr(,"class")
#> [1] "tm_scale_categorical" "tm_scale"             "list"                
#> 
#> $lwd.legend
#> $show
#> [1] FALSE
#> 
#> $called
#> [1] "show"
#> 
#> $title
#> [1] NA
#> 
#> $xlab
#> [1] NA
#> 
#> $ylab
#> [1] NA
#> 
#> $group_id
#> [1] NA
#> 
#> $group_type
#> [1] "tm_legend"
#> 
#> $z
#> [1] NA
#> 
#> attr(,"class")
#> [1] "tm_legend"    "tm_component" "list"        
#> 
#> $lty
#> [1] "road_type"
#> 
#> $lty.scale
#> $FUN
#> [1] "tmapScaleCategorical"
#> 
#> $n.max
#> [1] 30
#> 
#> $values
#> [1] "solid"  "dashed"
#> 
#> $values.repeat
#> [1] TRUE
#> 
#> $values.range
#> [1] NA
#> 
#> $values.scale
#> [1] NA
#> 
#> $value.na
#> [1] NA
#> 
#> $value.null
#> [1] NA
#> 
#> $value.neutral
#> [1] NA
#> 
#> $levels
#> [1] "highway"  "arterial"
#> 
#> $levels.drop
#> [1] TRUE
#> 
#> $labels
#> NULL
#> 
#> $label.na
#> [1] NA
#> 
#> $label.null
#> [1] NA
#> 
#> $label.format
#> list()
#> 
#> attr(,"class")
#> [1] "tm_scale_categorical" "tm_scale"             "list"                
#> 
#> $lty.legend
#> $show
#> [1] FALSE
#> 
#> $called
#> [1] "show"
#> 
#> $title
#> [1] NA
#> 
#> $xlab
#> [1] NA
#> 
#> $ylab
#> [1] NA
#> 
#> $group_id
#> [1] NA
#> 
#> $group_type
#> [1] "tm_legend"
#> 
#> $z
#> [1] NA
#> 
#> attr(,"class")
#> [1] "tm_legend"    "tm_component" "list"        
#> 

# Override classification field for alternative data source
# (e.g., bcfishpass barrier_status vs WHSE barrier_result_code)
gq_tmap_style(reg, "road", field = "my_road_type")
#> $col
#> [1] "my_road_type"
#> 
#> $col.scale
#> $FUN
#> [1] "tmapScaleCategorical"
#> 
#> $n.max
#> [1] 30
#> 
#> $values
#>   highway  arterial 
#> "#c0392b" "#e67e22" 
#> 
#> $values.repeat
#> [1] TRUE
#> 
#> $values.range
#> [1] NA
#> 
#> $values.scale
#> [1] NA
#> 
#> $value.na
#> [1] NA
#> 
#> $value.null
#> [1] NA
#> 
#> $value.neutral
#> [1] NA
#> 
#> $levels
#> [1] "highway"  "arterial"
#> 
#> $levels.drop
#> [1] TRUE
#> 
#> $labels
#> [1] "Highway"  "Arterial"
#> 
#> $label.na
#> [1] NA
#> 
#> $label.null
#> [1] NA
#> 
#> $label.format
#> list()
#> 
#> attr(,"class")
#> [1] "tm_scale_categorical" "tm_scale"             "list"                
#> 
#> $col.legend
#> $show
#> [1] FALSE
#> 
#> $called
#> [1] "show"
#> 
#> $title
#> [1] NA
#> 
#> $xlab
#> [1] NA
#> 
#> $ylab
#> [1] NA
#> 
#> $group_id
#> [1] NA
#> 
#> $group_type
#> [1] "tm_legend"
#> 
#> $z
#> [1] NA
#> 
#> attr(,"class")
#> [1] "tm_legend"    "tm_component" "list"        
#> 
#> $lwd
#> [1] "my_road_type"
#> 
#> $lwd.scale
#> $FUN
#> [1] "tmapScaleCategorical"
#> 
#> $n.max
#> [1] 30
#> 
#> $values
#> [1] 2.0 1.5
#> 
#> $values.repeat
#> [1] TRUE
#> 
#> $values.range
#> [1] NA
#> 
#> $values.scale
#> [1] NA
#> 
#> $value.na
#> [1] NA
#> 
#> $value.null
#> [1] NA
#> 
#> $value.neutral
#> [1] NA
#> 
#> $levels
#> [1] "highway"  "arterial"
#> 
#> $levels.drop
#> [1] TRUE
#> 
#> $labels
#> NULL
#> 
#> $label.na
#> [1] NA
#> 
#> $label.null
#> [1] NA
#> 
#> $label.format
#> list()
#> 
#> attr(,"class")
#> [1] "tm_scale_categorical" "tm_scale"             "list"                
#> 
#> $lwd.legend
#> $show
#> [1] FALSE
#> 
#> $called
#> [1] "show"
#> 
#> $title
#> [1] NA
#> 
#> $xlab
#> [1] NA
#> 
#> $ylab
#> [1] NA
#> 
#> $group_id
#> [1] NA
#> 
#> $group_type
#> [1] "tm_legend"
#> 
#> $z
#> [1] NA
#> 
#> attr(,"class")
#> [1] "tm_legend"    "tm_component" "list"        
#> 
#> $lty
#> [1] "my_road_type"
#> 
#> $lty.scale
#> $FUN
#> [1] "tmapScaleCategorical"
#> 
#> $n.max
#> [1] 30
#> 
#> $values
#> [1] "solid"  "dashed"
#> 
#> $values.repeat
#> [1] TRUE
#> 
#> $values.range
#> [1] NA
#> 
#> $values.scale
#> [1] NA
#> 
#> $value.na
#> [1] NA
#> 
#> $value.null
#> [1] NA
#> 
#> $value.neutral
#> [1] NA
#> 
#> $levels
#> [1] "highway"  "arterial"
#> 
#> $levels.drop
#> [1] TRUE
#> 
#> $labels
#> NULL
#> 
#> $label.na
#> [1] NA
#> 
#> $label.null
#> [1] NA
#> 
#> $label.format
#> list()
#> 
#> attr(,"class")
#> [1] "tm_scale_categorical" "tm_scale"             "list"                
#> 
#> $lty.legend
#> $show
#> [1] FALSE
#> 
#> $called
#> [1] "show"
#> 
#> $title
#> [1] NA
#> 
#> $xlab
#> [1] NA
#> 
#> $ylab
#> [1] NA
#> 
#> $group_id
#> [1] NA
#> 
#> $group_type
#> [1] "tm_legend"
#> 
#> $z
#> [1] NA
#> 
#> attr(,"class")
#> [1] "tm_legend"    "tm_component" "list"        
#> 

# Object-based (backwards compatible)
gq_tmap_style(reg$layers$lake)
#> $fill
#> [1] "#c6ddf0"
#> 
#> $fill_alpha
#> [1] 0.85
#> 
#> $col
#> [1] "#7ba7cc"
#> 
#> $lwd
#> [1] 0.5
#> 

# Use with tmap v4:
# tm_shape(lakes_sf) + do.call(tm_polygons, gq_tmap_style(reg, "lake"))
# tm_shape(roads_sf) + do.call(tm_lines, gq_tmap_style(reg, "road"))