split feature collection

[wiesehahn]

Sorry if this doesnt fit here, I guess its more a question than an issue.

I would like to read a STAC ItemCollection(a GeoJSON FeatureCollection that is augmented with foreign members) and save individual features to disk as seperate geojson.

t <- yyjsonr::read_json_conn("https://raw.githubusercontent.com/radiantearth/stac-api-spec/main/fragments/itemcollection/examples/itemcollection-sample-full.json")
features <- t$features

for (i in 1:nrow(features)) {
  feature <- features[i,]
  write_json_file(feature,
                  filename = here::here(paste0(feature$id, ".json")),
                  opts = opts_write_json(pretty = TRUE,
                                         auto_unbox = TRUE))
  
}

The output is as expected, except that it is wrapped as array in [ ]. I guess this is due to the json spec.

as is:

[
  {
    "stac_version": "1.0.0",
    "stac_extensions": [],
    "type": "Feature",
    "id": "cs3-20160503_132131_05",
    "bbox": [
      -122.59750209,
      37.48803556,
      -122.2880486,
      37.613537207
    ],
    "geometry": {
      "type": "Polygon",
      "coordinates": [
        [
          [
            -122.308150179,
            37.488035566
          ],
          [
            -122.597502109,
            37.538869539
          ],
          [
            -122.576687533,
            37.613537207
          ],
          [
            -122.2880486,
            37.562818007
          ],
          [
            -122.308150179,
            37.488035566
          ]
        ]
      ]
    },
    "properties": {
      "datetime": "2016-05-03T13:22:30.040Z",
      "title": "A CS3 item",
      "license": "PDDL-1.0",
      "providers": [
        {
          "name": "CoolSat",
          "roles": [
            "producer",
            "licensor"
          ],
          "url": "https://stac-api.example.com"
        }
      ]
    },
    "collection": "cs3",
    "links": [
      {
        "rel": "self",
        "type": "application/json",
        "href": "https://stac-api.example.com/collections/cs3/items/CS3-20160503_132131_05"
      },
      {
        "rel": "root",
        "type": "application/json",
        "href": "https://stac-api.example.com/"
      },
      {
        "rel": "collection",
        "type": "application/json",
        "href": "https://stac-api.example.com/collections/cs3"
      }
    ],
    "assets": {
      "analytic": {
        "href": "https://stac-api.example.com/catalog/cs3-20160503_132130_04/analytic.tif",
        "type": "image/tiff; application=geotiff; profile=cloud-optimized",
        "title": "4-Band Analytic"
      },
      "thumbnail": {
        "href": "https://stac-api.example.com/catalog/cs3-20160503_132130_04/thumbnail.png",
        "type": "image/png",
        "title": "Thumbnail",
        "roles": "thumbnail"
      }
    }
  }
]

as expected:

{
  "stac_version": "1.0.0",
  "stac_extensions": [],
  "type": "Feature",
  "id": "cs3-20160503_132131_05",
  "bbox": [
    -122.59750209,
    37.48803556,
    -122.2880486,
    37.613537207
  ],
  "geometry": {
    "type": "Polygon",
    "coordinates": [
      [
        [
          -122.308150179,
          37.488035566
        ],
        [
          -122.597502109,
          37.538869539
        ],
        [
          -122.576687533,
          37.613537207
        ],
        [
          -122.2880486,
          37.562818007
        ],
        [
          -122.308150179,
          37.488035566
        ]
      ]
    ]
  },
  "properties": {
    "datetime": "2016-05-03T13:22:30.040Z",
    "title": "A CS3 item",
    "license": "PDDL-1.0",
    "providers": [
      {
        "name": "CoolSat",
        "roles": [
          "producer",
          "licensor"
        ],
        "url": "https://stac-api.example.com"
      }
    ]
  },
  "collection": "cs3",
  "links": [
    {
      "rel": "self",
      "type": "application/json",
      "href": "https://stac-api.example.com/collections/cs3/items/CS3-20160503_132131_05"
    },
    {
      "rel": "root",
      "type": "application/json",
      "href": "https://stac-api.example.com/"
    },
    {
      "rel": "collection",
      "type": "application/json",
      "href": "https://stac-api.example.com/collections/cs3"
    }
  ],
  "assets": {
    "analytic": {
      "href": "https://stac-api.example.com/catalog/cs3-20160503_132130_04/analytic.tif",
      "type": "image/tiff; application=geotiff; profile=cloud-optimized",
      "title": "4-Band Analytic"
    },
    "thumbnail": {
      "href": "https://stac-api.example.com/catalog/cs3-20160503_132130_04/thumbnail.png",
      "type": "image/png",
      "title": "Thumbnail",
      "roles": "thumbnail"
    }
  }
}

What would be an appropriate way to save the files without the square brackets? Do I somehow need do convert the features to sf first and then use write_geojson_file()?

[wiesehahn]

While I still didnt found a nice solution the following at least does what it should

# Read the JSON file as a text string
json_content <- readLines(here::here(paste0(feature$id, ".json"), warn = FALSE)

# Collapse the lines into a single string
json_string <- paste(json_content, collapse = "\n")

# Remove the outer square brackets and any leading/trailing whitespace or newlines
json_string <- sub("^\\s*\\[\\s*", "", json_string)
json_string <- sub("\\s*\\]\\s*$", "", json_string)

# Write the modified JSON string to a new file
writeLines(json_string, here::here(paste0(feature$id, ".json"))