(arrow-rs) branch main updated: Minor: Add examples to ProjectionMask documentation (#7523)

[alamb]

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alamb pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/arrow-rs.git


The following commit(s) were added to refs/heads/main by this push:
     new c37f5a03ee Minor: Add examples to ProjectionMask documentation (#7523)
c37f5a03ee is described below

commit c37f5a03eed902759d0912425dfab4518e299501
Author: Andrew Lamb <and...@nerdnetworks.org>
AuthorDate: Mon May 19 10:04:27 2025 -0400

    Minor: Add examples to ProjectionMask documentation (#7523)
---
 parquet/src/arrow/mod.rs | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/parquet/src/arrow/mod.rs b/parquet/src/arrow/mod.rs
index 76f8ef1bf0..e15a8d9b02 100644
--- a/parquet/src/arrow/mod.rs
+++ b/parquet/src/arrow/mod.rs
@@ -251,10 +251,25 @@ pub const PARQUET_FIELD_ID_META_KEY: &str = 
"PARQUET:field_id";
 ///
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct ProjectionMask {
-    /// If present a leaf column should be included if the value at
+    /// If `Some`, a leaf column should be included if the value at
     /// the corresponding index is true
     ///
-    /// If `None`, include all columns
+    /// If `None`, all columns should be included
+    ///
+    /// # Examples
+    ///
+    /// Given the original parquet schema with leaf columns is `[a, b, c, d]`
+    ///
+    /// A mask of `[true, false, true, false]` will result in a schema 2
+    /// elements long:
+    /// * `fields[0]`: `a`
+    /// * `fields[1]`: `c`    
+    ///
+    /// A mask of `None` will result in a schema 4 elements long:
+    /// * `fields[0]`: `a`
+    /// * `fields[1]`: `b`
+    /// * `fields[2]`: `c`
+    /// * `fields[3]`: `d`
     mask: Option<Vec<bool>>,
 }