Hello, 

Apologies if this has already been addressed somewhere, I did a brief search
of archives but didn't find quite this issue.

I'm writing out an ESRI shapefile.  My spdf has a date/time field.  Looks
like this:

> head(spdfUTM@data)
           krillGMTtime          Lat          Lon
1   2010-05-12 12:34:21 -64.67655969 -62.15040195
21  2010-05-12 12:35:12  -64.6771229  -62.1519511
38  2010-05-12 12:36:02 -64.67775863 -62.15340614
57  2010-05-12 12:36:53 -64.67838269 -62.15494829
78  2010-05-12 12:37:43 -64.67901497 -62.15647203
100 2010-05-12 12:38:37 -64.67973667 -62.15773224
 
All three fields are reported to be "factors" by str.  writeOGR appears
happy:

> writeOGR(spdfUTM,dd,layer="krillPoints-UTM",driver="ESRI
Shapefile",verbose=TRUE,overwrite=TRUE)
$object_type
[1] "SpatialPointsDataFrame"
$output_dsn
[1] "/users/corriecurtice/documents/Data_2010/Shapefiles/"
$output_layer
[1] "krillPoints-UTM"
$output_diver
[1] "ESRI Shapefile"
$output_n
[1] 11179
$output_nfields
[1] 3
$output_fields
[1] "krillGMTtime" "Lat"          "Lon"
$output_fclasses
[1] 4 4 4
$dataset_options
NULL
$layer_options
NULL
Warning message:
In writeOGR(spdfUTM, dd, layer = "krillPoints-UTM", driver = "ESRI
Shapefile",  :
  existing layer removed

When I read it right back in again, the date/time field is NAs.  This is
also true if I load the shapefile into ArcMap.

> foo <- readOGR(dd,layer="krillPoints-UTM",verbose=TRUE)
OGR data source with driver: ESRI Shapefile
Source: "/users/corriecurtice/documents/Data_2010/Shapefiles/", layer:
"krillPoints-UTM"
with 11179 features and 3 fields
Feature type: wkbPoint with 2 dimensions

> head(foo@data)
  krillGMTti          Lat          Lon
1       <NA> -64.67655969 -62.15040195
2       <NA>  -64.6771229  -62.1519511
3       <NA> -64.67775863 -62.15340614
4       <NA> -64.67838269 -62.15494829
5       <NA> -64.67901497 -62.15647203
6       <NA> -64.67973667 -62.15773224

Thoughts? Am I missing something obvious?

I can break it up into separate date and time fields, but since the field is
simply a factor anyways I'm not sure how that would help.

Cheers,

Corrie

---
Corrie Curtice
Research Analyst
Marine Geospatial Ecology Lab
Nicholas School of the Environment, Duke University
http://mgel.env.duke.edu
em: corrie.curtice@duke.edu
ph: 252-504-7538




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