Fix Clojure BERT example's context argument (apache#14843)

* Clojure BERT example: minor code cleanup

* Remove unused requires
* Remove unused vars & function
* Use `io` alias

* Clojure BERT example: whitespace fix

* Clojure BERT example: allow running with GPU

The `infer` function accepts a CPU/GPU context, which the command line
version of this example exposes as a `:cpu`/`:gpu`
keyword. Previously, these options were ignored and the context was
overridden to the default context (CPU). This commit allows
users (both REPL and shell) to pass in a GPU context.

contrib/clojure-package/examples/bert-qa/README.md

@@ -57,9 +57,8 @@ Some sample questions and answers are provide in the `squad-sample.edn` file. So
 
 * `lein install` in the root of the main project directory
 * cd into this project directory and do `lein run`. This will execute the cpu version.
-
-`lein run :cpu` - to run with cpu
-`lein run :gpu` - to run with gpu
+  * `lein run` or `lein run :cpu` to run with cpu
+  * `lein run :gpu` to run with gpu
 
 ## Background
 

contrib/clojure-package/examples/bert-qa/src/bert_qa/infer.clj

@@ -15,13 +15,10 @@
 ;; limitations under the License.
 ;;
 
-
 (ns bert-qa.infer
   (:require [clojure.string :as string]
-            [clojure.reflect :as r]
             [cheshire.core :as json]
             [clojure.java.io :as io]
-            [clojure.set :as set]
             [org.apache.clojure-mxnet.dtype :as dtype]
             [org.apache.clojure-mxnet.context :as context]
             [org.apache.clojure-mxnet.layout :as layout]
@@ -30,11 +27,7 @@
             [clojure.pprint :as pprint]))
 
 (def model-path-prefix "model/static_bert_qa")
-;; epoch number of the model
-(def epoch 2)
-;; the vocabulary used in the model
-(def model-vocab "model/vocab.json")
-;; the input question
+
 ;; the maximum length of the sequence
 (def seq-length 384)
 
@@ -60,16 +53,13 @@
     (into tokens (repeat (- num (count tokens)) pad-item))))
 
 (defn get-vocab []
-  (let [vocab (json/parse-stream (clojure.java.io/reader "model/vocab.json"))]
+  (let [vocab (json/parse-stream (io/reader "model/vocab.json"))]
     {:idx->token (get vocab "idx_to_token")
      :token->idx (get vocab "token_to_idx")}))
 
 (defn tokens->idxs [token->idx tokens]
   (let [unk-idx (get token->idx "[UNK]")]
-   (mapv #(get token->idx % unk-idx) tokens)))
-
-(defn idxs->tokens [idx->token idxs]
-  (mapv #(get idx->token %) idxs))
+    (mapv #(get token->idx % unk-idx) tokens)))
 
 (defn post-processing [result tokens]
   (let [output1 (ndarray/slice-axis result 2 0 1)
@@ -131,22 +121,23 @@
      :tokens tokens
      :qa-map qa-map}))
 
-(defn infer [ctx]
-  (let [ctx (context/default-context)
-        predictor (make-predictor ctx)
-        {:keys [idx->token token->idx]} (get-vocab)
+(defn infer
+  ([] (infer (context/default-context)))
+  ([ctx]
+   (let [predictor (make-predictor ctx)
+         {:keys [idx->token token->idx]} (get-vocab)
         ;;; samples taken from https://rajpurkar.github.io/SQuAD-explorer/explore/v2.0/dev/
-        question-answers (clojure.edn/read-string (slurp "squad-samples.edn"))]
-    (doseq [qa-map question-answers]
-      (let [{:keys [input-batch tokens qa-map]} (pre-processing ctx idx->token token->idx qa-map)
-            result (first (infer/predict-with-ndarray predictor input-batch))
-            answer (post-processing result tokens)]
-        (println "===============================")
-        (println "      Question Answer Data")
-        (pprint/pprint qa-map)
-        (println)
-        (println "  Predicted Answer: " answer)
-        (println "===============================")))))
+         question-answers (clojure.edn/read-string (slurp "squad-samples.edn"))]
+     (doseq [qa-map question-answers]
+       (let [{:keys [input-batch tokens qa-map]} (pre-processing ctx idx->token token->idx qa-map)
+             result (first (infer/predict-with-ndarray predictor input-batch))
+             answer (post-processing result tokens)]
+         (println "===============================")
+         (println "      Question Answer Data")
+         (pprint/pprint qa-map)
+         (println)
+         (println "  Predicted Answer: " answer)
+         (println "==============================="))))))
 
 (defn -main [& args]
   (let [[dev] args]
@@ -156,4 +147,8 @@
 
 (comment
 
-  (infer :cpu))
+  (infer)
+
+  (infer (context/gpu))
+
+  )