[R-sig-Geo] Plot street "Name" for city streets (lines) in a SpatialLinesDataFrame

[Roger Bivand]

On Wed, 9 Sep 2015, Jim Burke wrote:

> Given a SpatialLinesDataFrame like below. How might I print the street
> "Name" adjacent to these many streets in the SpatialLinesDataFrame? Just
> what in the line class can I attach its "Name" to? I want to add this plot
> as a layer to my other plots.
>

Please no HTML mail. It is (much) bulkier, and can contain payloads, so 
all the R lists strip HTML copies/markup, often leading to garbled 
content.

Please provide a reproducible example, possibly with a small subset of OSM 
data or similar (by URL). Guessing from the structure below with 125K 
Lines objects would be hard, start small and scale up from there. Find a 
representative point, possibly a midpoint, for each "street" - probably 
Lines object - find its angle, and try to offset and rotate the inserted 
text.

In regular cartography, the placement of labels is generally considered 
hard. There are functions in the maptools package for label placement for 
point support to avoid overlapping, but these do not accommodate rotation.

Since you didn't say why you need this, it is hard to provide sensible 
advice. An affiliation would give an indication of the motivation.

Roger

> And I cannot post an code snippet example because I don't get that far
> here. This is more basic. I want some thoughts on how to plot a tiny street
> name near each street in the SpatialLinesDataFrame.
>
>> str(DC_Roads1_sp)
> Formal class 'SpatialLinesDataFrame' [package "sp"] with 4 slots
>  ..@ data       :'data.frame': 125059 obs. of  31 variables:
>  .. ..$ DC_ID    : num [1:125059] 843772 843773 844139 844140 844141 ...
>  .. ..$ Prefix   : chr [1:125059] NA NA NA "N" ...
>  .. ..$ Pretype  : chr [1:125059] NA NA "STHY" NA ...
>  .. ..$ Name     : chr [1:125059] "Freeport" "Freeport" "183" "Valley
> View" ...
>
> Then the line class looks like below (first two are shown)
>
> ..@ lines      :List of 125059
>  .. ..$ :Formal class 'Lines' [package "sp"] with 2 slots
>  .. .. .. ..@ Lines:List of 1
>  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
>  .. .. .. .. .. .. ..@ coords: num [1:2, 1:2] -97 -97 32.9 32.9
>  .. .. .. ..@ ID   : chr "0"
>  .. ..$ :Formal class 'Lines' [package "sp"] with 2 slots
>  .. .. .. ..@ Lines:List of 1
>  .. .. .. .. ..$ :Formal class 'Line' [package "sp"] with 1 slot
>  .. .. .. .. .. .. ..@ coords: num [1:2, 1:2] -97 -97 32.9 32.9
>  .. .. .. ..@ ID   : chr "1"
>
>
> Any and all advice/suggestions/hints/examples is appreciated.
>
> Thanks,
> Jim Burke
>
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-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 91 00
e-mail: Roger.Bivand at nhh.no