Added :replace-missing-values filter and updated readme.

README.md

@@ -27,6 +27,7 @@ A machine learning library for Clojure built on top of Weka and friends.
    * String to word vector
    * Attribute manipulation (reorder, add, remove range, remove percentage, etc.)
    * Resample (supervised, unsupervised)
+   * Replace missing values with mean (numeric attributes) or mode (nominal attributes)
 
  * Classifiers
    * k-Nearest neighbor
@@ -550,6 +551,8 @@ user> titanicds
 ...
 >
 
+user> (def titanicds (make-apply-filter :replace-missing-values {} titanicds))
+
 user> (def titanicds (make-apply-filter :remove-attributes
                                         {:attributes [:PassengerId :Name :Ticket :Cabin]}
                                         titanicds))
@@ -621,6 +624,7 @@ user> titanic-test-passids
 user> (def titanic-testds (->> titanic-testds
                                (make-apply-filter :remove-attributes
                                                   {:attributes [:PassengerId :Name :Ticket :Cabin]})
+                               (make-apply-filter :replace-missing-values {})
                                (make-apply-filter :add-attribute
                                                   {:type :nominal :name :Survived
                                                    :column 0 :labels ["0" "1"]})))

src/clj_ml/filters.clj

@@ -206,6 +206,12 @@
 
 (deffilter resample-supervised)
 
+(defmethod make-filter-options :replace-missing-values
+  ([kind m]
+     (check-options m {:unset-class-temporarily "-unset-class-temporarily"})))
+
+(deffilter replace-missing-values)
+
 (defmethod make-filter-options :select-append-attributes
   ([kind m]
      (->> (extract-attributes m)
@@ -245,6 +251,7 @@
    :resample-unsupervised weka.filters.unsupervised.instance.Resample
    :resample-supervised weka.filters.supervised.instance.Resample
    :select-append-attributes weka.filters.unsupervised.attribute.Copy
+   :replace-missing-values weka.filters.unsupervised.attribute.ReplaceMissingValues
    :project-attributes weka.filters.unsupervised.attribute.Remove})
 
 
@@ -269,6 +276,7 @@
      - :resample-unsupervised
      - :resample-supervised
      - :select-append-attributes
+     - :replace-missing-values
      - :project-attributes
      - :clj-streamable
      - :clj-batch
@@ -377,6 +385,7 @@
       Parameters:
 
         - :attributes
+
             Index of the attributes to be transformed. Sample value: [0 1 2]
             The attributes may also be specified by names as well: [:some-name, \"another-name\"]
         - :invert
@@ -508,6 +517,17 @@
         - :invert
             Invert the selection of the columns. Sample value: true
 
+    * :replace-missing-values
+
+      Replaces all missing values for nominal and numeric attributes
+      in a dataset with the modes and means from the training data.
+
+      Parameters:
+
+        - :unset-class-temporarily
+            Unsets the class index temporarily before the filter is
+            applied to the data. Sample value: true; default: false
+
     * :project-attributes
 
       Project some columns from the provided dataset