Running examples in ‘tweet2r-Ex.R’ failed
The error most likely occurred in:

> ### Name: tspan
> ### Title: Exploratory point pattern analysis.
> ### Aliases: tspan
> ### Keywords: point pattern
> 
> ### ** Examples
> 
> library(sp)
> library(spatstat)
Loading required package: spatstat.data
Loading required package: nlme
Loading required package: rpart

spatstat 1.64-1       (nickname: ‘Help you I can, yes!’) 
For an introduction to spatstat, type ‘beginner’ 


Note: spatstat version 1.64-1 is out of date by more than 12 weeks; a newer version should be available.
> 
> #loada a SpatialPointsDataFrame
> data("meuse.grid_ll")
> 
> 
> # run function without contour
> tspan(meuse.grid_ll,bw=0.0005)
working window is the input geotweets bounding box.
$tweetsppp
Planar point pattern: 3103 points
window: rectangle = [5.721109, 5.76517] x [50.95577, 50.99272] units

$hp
Stationary Poisson process
Intensity: 1906125
            Estimate       S.E. CI95.lo  CI95.hi Ztest     Zval
log(lambda) 14.46058 0.01795185 14.4254 14.49577   *** 805.5207

$ihp
Nonstationary Poisson process

Log intensity:  ~x + y

Fitted trend coefficients:
(Intercept)           x           y 
1375.906599   -1.465591  -26.544168 

               Estimate      S.E.     CI95.lo     CI95.hi Ztest       Zval
(Intercept) 1375.906599 88.225280 1202.988227 1548.824970   ***  15.595378
x             -1.465591  1.411571   -4.232218    1.301037        -1.038269
y            -26.544168  1.723565  -29.922292  -23.166043   *** -15.400738

$int
real-valued pixel image
128 x 128 pixel array (ny, nx)
enclosing rectangle: [5.7211, 5.7652] x [50.956, 50.993] units

> 
> #providing a contour as SpatialPointDataFrame
> data("meuse.area")
> 
> #build the acontour layer 
> cont<-SpatialPoints(meuse.area, proj4string = CRS("+init=epsg:28992"))
> #transform to meuse.grid_ll reference system
> cont<-spTransform(cont, CRS("+init=epsg:4326"))
Warning in wkt(obj) : CRS object has no comment
Warning in wkt(CRS(tg)) : CRS object has no comment
Error in project(t(bbox(obj))[, 1:2], tg, inv = TRUE, use_aoi = FALSE) : 
  is.character(proj) is not TRUE
Calls: spTransform -> spTransform -> get_aoi -> project -> stopifnot
Execution halted