Can group cells by given column name.

src/commands/count.rs

@@ -20,7 +20,7 @@ impl WholeStreamCommand for Count {
     }
 
     fn usage(&self) -> &str {
-        "Show the total number of rows."
+        "Show the total number of cells."
     }
 
     fn run(

src/commands/group_by.rs

@@ -0,0 +1,59 @@
+use crate::commands::WholeStreamCommand;
+use crate::data::TaggedDictBuilder;
+use crate::errors::ShellError;
+use crate::prelude::*;
+
+pub struct GroupBy;
+
+#[derive(Deserialize)]
+pub struct GroupByArgs {
+    column_name: Tagged<String>,
+}
+
+impl WholeStreamCommand for GroupBy {
+    fn name(&self) -> &str {
+        "group-by"
+    }
+
+    fn signature(&self) -> Signature {
+        Signature::build("group-by").required("column_name", SyntaxShape::String)
+    }
+
+    fn usage(&self) -> &str {
+        "Creates a new table with the data from the table rows grouped by the column given."
+    }
+
+    fn run(
+        &self,
+        args: CommandArgs,
+        registry: &CommandRegistry,
+    ) -> Result<OutputStream, ShellError> {
+        args.process(registry, group_by)?.run()
+    }
+}
+
+fn group_by(
+    GroupByArgs { column_name }: GroupByArgs,
+    RunnableContext { input, name, .. }: RunnableContext,
+) -> Result<OutputStream, ShellError> {
+    let stream = async_stream! {
+        let values: Vec<Tagged<Value>> = input.values.collect().await;
+        let mut groups = indexmap::IndexMap::new();
+
+        for row in values {
+            let key = row.get_data_by_key(&column_name.item).unwrap().as_string()?;
+            let mut group = groups.entry(key).or_insert(vec![]);
+            group.push(row);
+        }
+
+        let mut out = TaggedDictBuilder::new(name.clone());
+
+        for (k,v) in groups.iter() {
+            out.insert(k, Value::table(v));
+        }
+
+        yield ReturnSuccess::value(out)
+    };
+
+    Ok(stream.to_output_stream())
+}