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I have a individual land price data, and I am trying to get the flood hazard zone category using the flood hazard zone shape file (link here https://files.hawaii.gov/dbedt/op/gis/data/s_fld_haz_ar_state.zip) in R. The first 5 sample of land price data (from shapefile) is in the link below: https://drive.google.com/file/d/1HSN9e48CncqV0IRDqx41Ubf3fazhB-ey/view (I can't dput here because of limitation on characters of the question) .

    library(sf)
    flood_zone_sf<-read_sf("s_fld_haz_ar_state.shp")
 # the variable I am interested is FLD_ZONE. 
flood_zone_sf

flood_zone_sf
Simple feature collection with 14676 features and 21 fields
Geometry type: POLYGON
Dimension:     XY
Bounding box:  xmin: -160.2471 ymin: 18.90852 xmax: -154.8049 ymax: 22.23527
Geodetic CRS:  WGS 84 (with axis order normalized for visualization)
First 10 features:
   DFIRM_ID VERSION_ID FLD_AR_ID STUDY_TYP FLD_ZONE ZONE_SUBTY SFHA_TF STATIC_BFE V_DATUM DEPTH LEN_UNIT VELOCITY VEL_UNIT AR_REVERT AR_SUBTRV BFE_REVERT DEP_REVERT DUAL_ZONE    SOURCE_CIT Shape_Leng Shape_Area
1    15001C    1.1.1.0  15001C_1        NP       AE       <NA>       T         19     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA>   15001C_FIS1  1021.7487  10228.030
2    15001C    1.1.1.0  15001C_2        NP       AE       <NA>       T         10     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA> 15001C_STUDY6   396.2263   3168.708
3    15001C    1.1.1.0  15001C_3        NP       AE       <NA>       T      -9999    <NA> -9999     <NA>    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA>   15001C_FIS1  1652.8730  56536.222
4    15001C    1.1.1.0  15001C_4        NP       VE       <NA>       T         46     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA> 15001C_STUDY6   883.2431  47108.242
5    15001C    1.1.1.0  15001C_5        NP       VE       <NA>       T         22     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA> 15001C_STUDY6  1975.2465 157356.794
6    15001C    1.1.1.0  15001C_6        NP       VE       <NA>       T         14     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA> 15001C_STUDY6   963.0295  53570.545
7    15001C    1.1.1.0  15001C_7        NP       VE       <NA>       T         26     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA> 15001C_STUDY6  1066.6585  63543.361
8    15001C    1.1.1.0  15001C_8        NP       VE       <NA>       T         42     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA> 15001C_STUDY6   912.4932  49507.926
9    15001C    1.1.1.0  15001C_9        NP       VE       <NA>       T         26     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA> 15001C_STUDY6  1300.7773  93243.093
10   15001C    1.1.1.0 15001C_10        NP       VE       <NA>       T         10     MSL -9999     Feet    -9999     <NA>      <NA>      <NA>      -9999      -9999      <NA> 15001C_STUDY6  1715.9454 161528.883
                         geometry
1  POLYGON ((-155.6412 18.9361...
2  POLYGON ((-155.7276 18.9674...
3  POLYGON ((-155.6204 18.9688...
4  POLYGON ((-155.5913 18.9951...
5  POLYGON ((-155.5861 18.9999...
6  POLYGON ((-155.585 19.00383...
7  POLYGON ((-155.5841 19.0064...
8  POLYGON ((-155.5826 19.0054...
9  POLYGON ((-155.5823 19.0115...
10 POLYGON ((-155.5781 19.0169...

land_data_sf
   

     Simple feature collection with 5 features and 1 field
Geometry type: MULTIPOLYGON
Dimension:     XY
Bounding box:  xmin: -157.9444 ymin: 21.33355 xmax: -157.9072 ymax: 21.3442
Geodetic CRS:  WGS 84
  meansaleprice                       geometry
1        415000 MULTIPOLYGON (((-157.9414 2...
2        415000 MULTIPOLYGON (((-157.9414 2...
3       5228200 MULTIPOLYGON (((-157.9072 2...
4       5228200 MULTIPOLYGON (((-157.9072 2...
5       5228200 MULTIPOLYGON (((-157.9072 2...

How do I extract FLD_ZONE from flood hazard zone shapefile for the land price shapefile using R?

I have used st_join but I am getting error.

st_join(jj,flood_zone_sf)
Error in wk_handle.wk_wkb(wkb, s2_geography_writer(oriented = oriented,  : 
  Loop 0 is not valid: Edge 4851 has duplicate vertex with edge 5006
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1 Answer 1

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Not sure where jj is coming from, but the error message is quite explicit about geometry issues, which you can check and solve using {sf}.

Out of 14,676 objects of s_fld_haz_ar_state.shp, 36 objects seem to have invalid geometry:

library(sf)
#> Linking to GEOS 3.9.3, GDAL 3.5.2, PROJ 8.2.1; sf_use_s2() is TRUE

# import shp
flood_zone_sf <- read_sf("s_fld_haz_ar_state.shp") 

# get number of objects
dim(flood_zone_sf)[1]
#> [1] 14676

# check for geometry issues
st_is_valid(flood_zone_sf) |> sum()
#> [1] 14640

From my point of view, you can solve this quite easily via st_make_valid() and continue with st_join() after harmonizing coordinate reference systems in order to join the attributes of flood_zone_sf on land_price_sf based on geometry information:

st_crs(land_price_sf)$epsg
#> [1] 4326

# reproject and make valid
flood_zone_sf <- flood_zone_sf |> sf::st_transform("epsg:4326") |> sf::st_make_valid()

# spatial join
lpfz_sf <- sf::st_join(land_price_sf, flood_zone_sf)

head(lpfz_sf)
#> Simple feature collection with 6 features and 22 fields
#> Geometry type: MULTIPOLYGON
#> Dimension:     XY
#> Bounding box:  xmin: -157.9444 ymin: 21.33355 xmax: -157.9072 ymax: 21.3442
#> Geodetic CRS:  WGS 84
#>     meansaleprice DFIRM_ID VERSION_ID   FLD_AR_ID STUDY_TYP FLD_ZONE ZONE_SUBTY
#> 1          415000   15003C    1.1.1.0   15003C_43        NP        D       <NA>
#> 1.1        415000   15003C    1.1.1.0 15003C_1250        NP        D       <NA>
#> 2          415000   15003C    1.1.1.0   15003C_43        NP        D       <NA>
#> 2.1        415000   15003C    1.1.1.0 15003C_1250        NP        D       <NA>
#> 3         5228200   15003C    1.1.1.0 15003C_1250        NP        D       <NA>
#> 4         5228200   15003C    1.1.1.0 15003C_1250        NP        D       <NA>
#>     SFHA_TF STATIC_BFE V_DATUM DEPTH LEN_UNIT VELOCITY VEL_UNIT AR_REVERT
#> 1         F      -9999    <NA> -9999     <NA>    -9999     <NA>      <NA>
#> 1.1       F      -9999    <NA> -9999     <NA>    -9999     <NA>      <NA>
#> 2         F      -9999    <NA> -9999     <NA>    -9999     <NA>      <NA>
#> 2.1       F      -9999    <NA> -9999     <NA>    -9999     <NA>      <NA>
#> 3         F      -9999    <NA> -9999     <NA>    -9999     <NA>      <NA>
#> 4         F      -9999    <NA> -9999     <NA>    -9999     <NA>      <NA>
#>     AR_SUBTRV BFE_REVERT DEP_REVERT DUAL_ZONE  SOURCE_CIT Shape_Leng Shape_Area
#> 1        <NA>      -9999      -9999      <NA> 15003C_FIS1   21527.26    5408537
#> 1.1      <NA>      -9999      -9999      <NA>          NP   46849.28   20547349
#> 2        <NA>      -9999      -9999      <NA> 15003C_FIS1   21527.26    5408537
#> 2.1      <NA>      -9999      -9999      <NA>          NP   46849.28   20547349
#> 3        <NA>      -9999      -9999      <NA>          NP   46849.28   20547349
#> 4        <NA>      -9999      -9999      <NA>          NP   46849.28   20547349
#>                           geometry
#> 1   MULTIPOLYGON (((-157.9414 2...
#> 1.1 MULTIPOLYGON (((-157.9414 2...
#> 2   MULTIPOLYGON (((-157.9414 2...
#> 2.1 MULTIPOLYGON (((-157.9414 2...
#> 3   MULTIPOLYGON (((-157.9072 2...
#> 4   MULTIPOLYGON (((-157.9072 2...
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