expose ImgXY and LonLat types from wcs/mapproj

cds-astro · Feb 21, 2025 · fa5843f · fa5843f
1 parent 6a1b51e
commit fa5843f
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Showing 3 changed files with 49 additions and 9 deletions.
diff --git a/README.md b/README.md
@@ -73,6 +73,7 @@ Example
 use std::fs::File;
 use std::io::Cursor;
 use fitsrs::{Fits, ImageData, HDU, hdu::header::Xtension};
+use fitsrs::wcs::{ImgXY, LonLat};
 
 use std::io::{BufReader, Read};
 
@@ -93,6 +94,23 @@ while let Some(Ok(hdu)) = hdu_list.next() {
 
             let num_pixels = (naxis2 * naxis1) as usize;
 
+            // Try to access the WCS for an HDU image
+            if let Ok(wcs) = hdu.wcs() {
+                // Get the lonlat position on the sky of the pixel located at (0, 0) on the image
+                let xy = ImgXY::new(0.0, 0.0);
+                let lonlat = wcs
+                    .unproj_lonlat(&xy)
+                    .unwrap();
+
+                // Get the pixel position in the image of a sky location
+                let xy_2 = wcs
+                    .proj_lonlat(&lonlat)
+                    .unwrap();
+
+                assert!((xy.x() - xy_2.x()).abs() <= 1e-9);
+                assert!((xy.y() - xy_2.y()).abs() <= 1e-9);
+            }
+
             match hdu_list.get_data(&hdu) {
                 ImageData::U8(it) => {
                     let data = it.collect::<Vec<_>>();
@@ -121,13 +139,24 @@ while let Some(Ok(hdu)) = hdu_list.next() {
             }
         },
         HDU::XBinaryTable(hdu) => {
+            /*let data: Vec<_> = hdu_list
+                .get_data(&hdu)
+                .table_data()
+                // Select specific fields with the select_fields method
+                .select_fields(&[
+                    ColumnId::Name("mag"),
+                    ColumnId::Name("phot_bp_mean_mag"),
+                    ColumnId::Name("phot_rp_mean_mag"),
+                ])
+                .collect();
+            */
             let num_rows = hdu.get_header()
                 .get_xtension()
                 .get_num_rows();
-
-            let rows = hdu_list.get_data(&hdu)
+            let rows: Vec<_> = hdu_list
+                .get_data(&hdu)
                 .row_iter()
-                .collect::<Vec<_>>();
+                .collect();
 
             assert_eq!(num_rows, rows.len());
         },

diff --git a/src/lib.rs b/src/lib.rs
@@ -39,7 +39,8 @@ pub mod card;
 pub mod error;
 pub mod file;
 pub mod fits;
-mod wcs;
+pub mod wcs;
+
 mod gz;
 pub mod hdu;
 
@@ -58,6 +59,7 @@ mod tests {
     use crate::hdu::data::DataStream;
     use crate::hdu::AsyncHDU;
     use crate::{FITSFile, ImageData};
+    use crate::wcs::ImgXY;
 
     use crate::hdu::data::bintable::ColumnId;
     use crate::hdu::header::extension::Xtension;
@@ -236,7 +238,6 @@ mod tests {
     fn test_fits_not_fitting_in_memory() {
         use std::fs::File;
         use std::io::BufReader;
-
         let f = File::open("samples/fits.gsfc.nasa.gov/EUVE.fits").unwrap();
         let reader = BufReader::new(f);
         let mut hdu_list = Fits::from_reader(reader);
@@ -248,6 +249,15 @@ mod tests {
 
             let num_pixels = (naxis1 * naxis2) as usize;
 
+            // Try to access the WCS on a specific HDU image
+            if let Ok(wcs) = hdu.wcs() {
+                // and perform projection/unprojection using that image WCS
+                let xy = ImgXY::new(0.0, 0.0);
+                let _lonlat = wcs
+                    .unproj_lonlat(&xy)
+                    .unwrap();
+            }
+
             match hdu_list.get_data(&hdu) {
                 ImageData::I16(it) => {
                     let data = it.collect::<Vec<_>>();
@@ -310,8 +320,8 @@ mod tests {
         let reader = BufReader::new(f);
         let mut hdu_list = Fits::from_reader(reader);
         let mut data = vec![];
-        while let Some(Ok(hdu)) = dbg!(hdu_list.next()) {
-            match dbg!(hdu) {
+        while let Some(Ok(hdu)) = hdu_list.next() {
+            match hdu {
                 HDU::XBinaryTable(hdu) => {
                     let _ = hdu.get_header().get_xtension();
                     data = hdu_list.get_data(&hdu).collect::<Vec<_>>();
@@ -344,8 +354,6 @@ mod tests {
                         ])
                         .collect();
 
-                    let data = dbg!(data);
-
                     assert_eq!(data.len(), 3 * 52);
                 }
                 _ => (),

diff --git a/src/wcs.rs b/src/wcs.rs
@@ -6,6 +6,9 @@ use crate::error::Error;
 use crate::card::CardValue;
 use std::str::FromStr;
 
+pub type ImgXY = wcs::ImgXY;
+pub type LonLat = wcs::LonLat;
+
 use wcs::WCS;
 use crate::fits::HDU;
 use std::convert::TryInto;