Add some optional repeat penalty. (#623)

* Add some optional repeat penalty.

* Add the missing files.

candle-examples/examples/llama/main.rs

@@ -83,6 +83,14 @@ struct Args {
     /// (same structure as huggingface online)
     #[arg(long)]
     local_weights: Option<String>,
+
+    /// Penalty to be applied for repeating tokens, 1. means no penalty.
+    #[arg(long, default_value_t = 1.0)]
+    repeat_penalty: f32,
+
+    /// The context size to consider for the repeat penalty.
+    #[arg(long, default_value_t = 64)]
+    repeat_last_n: usize,
 }
 
 fn main() -> Result<()> {
@@ -200,6 +208,16 @@ fn main() -> Result<()> {
         let input = Tensor::new(ctxt, &device)?.unsqueeze(0)?;
         let logits = llama.forward(&input, index_pos)?;
         let logits = logits.squeeze(0)?;
+        let logits = if args.repeat_penalty == 1. {
+            logits
+        } else {
+            let start_at = tokens.len().saturating_sub(args.repeat_last_n);
+            candle_transformers::utils::apply_repeat_penalty(
+                &logits,
+                args.repeat_penalty,
+                &tokens[start_at..],
+            )?
+        };
         index_pos += ctxt.len();
 
         let next_token = logits_processor.sample(&logits)?;