Math Documentation (#1982)

* Adding math docs

* Add some comments to calculate

* Remove redudant message

Message already shows up in subcommands list

* Added not working example

Accidentantly

* Remove table

crates/nu-cli/src/commands/math/command.rs

@@ -16,11 +16,7 @@ impl WholeStreamCommand for Command {
     }
 
     fn usage(&self) -> &str {
-        r#"Use mathematical functions (average, min, max) to aggregate list of numbers or tables
-        math average
-        math min
-        math max
-        "#
+        "Use mathematical functions as aggregate functions on a list of numbers or tables"
     }
 
     async fn run(
@@ -97,6 +93,17 @@ mod tests {
                 expected_err: None,
                 expected_res: vec![Ok(decimal(-5)), Ok(decimal(-13.5)), Ok(int(10))],
             },
+            // TODO-Uncomment once I figure out how to structure tables
+            // TestCase {
+            //     description: "Tables",
+            //     values: vec![
+            //         table(&vec![int(3), int(4), int(4)]),
+            //         table(&vec![int(3), int(4), int(4)]),
+            //         table(&vec![int(3), int(4), int(4)]),
+            //     ],
+            //     expected_err: None,
+            //     expected_res: vec![Ok(decimal(-5)), Ok(decimal(-13.5)), Ok(int(10))],
+            // },
             // TODO-Uncomment once Issue: https://github.com/nushell/nushell/issues/1883 is resolved
             // TestCase {
             //     description: "Invalid Mixed Values",

crates/nu-cli/src/commands/math/utils.rs

@@ -20,6 +20,8 @@ pub async fn calculate(
             Err(err) => Err(err),
         }
     } else {
+        // If we are not dealing with Primitives, then perhaps we are dealing with a table
+        // Create a key for each column name
         let mut column_values = IndexMap::new();
         for value in values {
             if let UntaggedValue::Row(row_dict) = value.value {
@@ -31,7 +33,7 @@ pub async fn calculate(
                 }
             }
         }
-
+        // The mathematical function operates over the columns of the table
         let mut column_totals = IndexMap::new();
         for (col_name, col_vals) in column_values {
             match mf(&col_vals, &name) {