library(rgeos)

ls("package:rgeos") %>% .[grep("^g[A-Z]", .)]

##  [1] "gArea"                  "gBinarySTRtreeQuery"   
##  [3] "gBoundary"              "gBuffer"               
##  [5] "gCentroid"              "gContains"             
##  [7] "gContainsProperly"      "gConvexHull"           
##  [9] "gCoveredBy"             "gCovers"               
## [11] "gCrosses"               "gDelaunayTriangulation"
## [13] "gDifference"            "gDisjoint"             
## [15] "gDistance"              "gEnvelope"             
## [17] "gEquals"                "gEqualsExact"          
## [19] "gInterpolate"           "gIntersection"         
## [21] "gIntersects"            "gIsEmpty"              
## [23] "gIsRing"                "gIsSimple"             
## [25] "gIsValid"               "gLength"               
## [27] "gLineMerge"             "gNearestPoints"        
## [29] "gNode"                  "gOverlaps"             
## [31] "gPointOnSurface"        "gPolygonize"           
## [33] "gProject"               "gRelate"               
## [35] "gSimplify"              "gSymdifference"        
## [37] "gTouches"               "gUnarySTRtreeQuery"    
## [39] "gUnaryUnion"            "gUnion"                
## [41] "gUnionCascaded"         "gWithin"               
## [43] "gWithinDistance"

class(sp_quakes)

## [1] "SpatialPointsDataFrame"
## attr(,"package")
## [1] "sp"

ch <- gConvexHull(sp_quakes)
class(ch)

## [1] "SpatialPolygons"
## attr(,"package")
## [1] "sp"

plot(sp_quakes, col = "blue")
plot(ch, add = TRUE)

africa <- readOGR("../FOSSGIS-workshop/data/africa.js")

## OGR data source with driver: GeoJSON 
## Source: "../FOSSGIS-workshop/data/africa.js", layer: "OGRGeoJSON"
## with 54 features
## It has 65 fields

sp::spplot(africa, "LABELRANK", scales = list(draw = TRUE))

gUnionCascaded(africa) %>% plot(col = "blue")