BlakeOrth commented on code in PR #8801:
URL: https://github.com/apache/arrow-rs/pull/8801#discussion_r2504961693
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parquet-geospatial/src/crs.rs:
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@@ -0,0 +1,97 @@
+use std::{collections::HashMap, sync::Arc};
+
+use arrow_schema::{Schema, SchemaBuilder};
+use serde_json::{Value, json};
+
+#[derive(Debug)]
+pub enum Crs {
+ Projjson(serde_json::Value),
+ Srid(u64),
+ Other(String),
+}
+
+impl Crs {
+ // TODO: make fallible
+ fn try_from_parquet_str(crs: &str, metadata: &HashMap<String, String>) ->
Self {
+ let de: Value = serde_json::from_str(crs).unwrap();
+
+ // A CRS that does not exist or is empty defaults to 4326
+ // TODO: http link to parquet geospatial doc
+ let Some(crs) = de["crs"].as_str() else {
+ return Crs::Srid(4326);
+ };
Review Comment:
Can you help me understand this a bit better?
This code was an attempt to solve the case where a parquet file omits the
CRS metadata. The spec states:
> The default CRS OGC:CRS84 means that the geospatial features must be
stored in the order of longitude/latitude based on the WGS84 datum.
> ...
> For geographic CRS, longitudes are bound by [-180, 180] and latitudes are
bound by [-90, 90].
Doesn't this functionally bind an unspecified CRS to `SRID:4326` ?
`SRID:3857` also WGS84 datum, but it doesn't satisfy the lon/lat bounding
conditions.
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