From 43523220a4d0718adc406b3845d54b28d96bd120 Mon Sep 17 00:00:00 2001
From: Gary Linscott <glinscott@gmail.com>
Date: Sat, 25 Mar 2023 13:33:42 -0700
Subject: [PATCH] Remove perplexity from main

---
 examples/main/main.cpp | 80 ------------------------------------------
 1 file changed, 80 deletions(-)

diff --git a/examples/main/main.cpp b/examples/main/main.cpp
index d4cd3fbad..7bb2b6bc4 100644
--- a/examples/main/main.cpp
+++ b/examples/main/main.cpp
@@ -74,86 +74,6 @@ void set_console_state(console_state new_st) {
     }
 }
 
-std::vector<double> softmax(const std::vector<float>& logits) {
-    std::vector<double> probs(logits.size());
-    float max_logit = logits[0];
-    for (float v : logits) max_logit = std::max(max_logit, v);
-    double sum_exp = 0.0;
-    for (size_t i = 0; i < logits.size(); i++) {
-        // Subtract the maximum logit value from the current logit value for numerical stability
-        float logit = logits[i] - max_logit;
-        double exp_logit = std::exp(logit);
-        sum_exp += exp_logit;
-        probs[i] = exp_logit;
-    }
-    for (size_t i = 0; i < probs.size(); i++) probs[i] /= sum_exp;
-    return probs;
-}
-
-void perplexity(llama_context * ctx, const gpt_params & params) {
-    // Download: https://s3.amazonaws.com/research.metamind.io/wikitext/wikitext-2-raw-v1.zip?ref=salesforce-research
-    // Run `./main --perplexity -m models/7B/ggml-model-q4_0.bin -f wiki.test.raw`
-    // Output: `perplexity: 13.5106 [114/114]`
-    auto tokens = ::llama_tokenize(ctx, params.prompt, true);
-
-    int count = 0;
-    double nll = 0.0;
-    int seq_count = tokens.size() / params.n_ctx;
-    int n_vocab = llama_n_vocab(ctx);
-
-    fprintf(stderr, "%s : calculating perplexity over %d chunks, batch_size=%d\n", __func__, seq_count, params.n_batch);
-
-    for (int i = 0; i < seq_count; ++i) {
-        int start = i * params.n_ctx;
-        int end = start + params.n_ctx - 1;
-
-        std::vector<float> logits;
-        int num_batches = (params.n_ctx + params.n_batch - 1) / params.n_batch;
-        auto start_t = std::chrono::high_resolution_clock::now();
-        for (int j = 0; j < num_batches; ++j) {
-            int batch_start = start + j * params.n_batch;
-            int batch_size = std::min(end - batch_start, params.n_batch);
-            if (llama_eval(ctx, tokens.data() + batch_start, batch_size, j * params.n_batch, params.n_threads)) {
-                fprintf(stderr, "%s : failed to eval\n", __func__);
-                return;
-            }
-            auto batch_logits = llama_get_logits(ctx);
-            logits.insert(logits.end(), batch_logits, batch_logits + batch_size * n_vocab);
-        }
-        auto end_t = std::chrono::high_resolution_clock::now();
-        if (i == 0) {
-            double seconds = std::chrono::duration<double>(end_t - start_t).count();
-            printf("%.2f seconds per pass - ETA %.2f hours\n", seconds, (seconds * seq_count) / (60.0*60.0));
-        }
-        // We get the logits for all the tokens in the context window (params.n_ctx)
-        // from llama_eval above.  Now, based on https://huggingface.co/docs/transformers/perplexity,
-        // calculate the perplexity over the last half the window (so the model always has
-        // some context to predict the token).
-        //
-        // We rely on the fact that attention in the forward pass only looks at previous
-        // tokens here, so the logits returned for each token are an accurate representation
-        // of what the model would have predicted at that point.
-        //
-        // Example, we have a context window of 512, we will compute perplexity for each of the
-        // last 256 tokens.  Then, we split the input up into context window size chunks to
-        // process the entire prompt.
-
-        for (int j = params.n_ctx / 2; j < params.n_ctx - 1; ++j) {
-            // Calculate probability of next token, given the previous ones.
-            std::vector<float> tok_logits(
-                logits.begin() + j * n_vocab,
-                logits.begin() + (j + 1) * n_vocab);
-            double prob = softmax(tok_logits)[tokens[start + j + 1]];
-            nll += -std::log(prob);
-            ++count;
-        }
-        // perplexity is e^(average negative log-likelihood)
-        printf("[%d]%.4lf,", i + 1, std::exp(nll / count));
-        fflush(stdout);
-    }
-    printf("\n");
-}
-
 static bool is_interacting = false;
 
 #if defined (__unix__) || (defined (__APPLE__) && defined (__MACH__)) || defined (_WIN32)