Merge pull request ipython#893 from minrk/clearoutput

Adding clear_output to kernel and HTML notebook.

This enables the clearing of output during the execution of a cell. It can be used for simple forms of animation in the notebook.

IPython/core/display.py

@@ -381,3 +381,27 @@ def _repr_jpeg_(self):
 
     def _find_ext(self, s):
         return unicode(s.split('.')[-1].lower())
+
+
+def clear_output(stdout=True, stderr=True, other=True):
+    """Clear the output of the current cell receiving output.
+    
+    Optionally, each of stdout/stderr or other non-stream data (e.g. anything
+    produced by display()) can be excluded from the clear event.
+    
+    By default, everything is cleared.
+    
+    Parameters
+    ----------
+    stdout : bool [default: True]
+        Whether to clear stdout.
+    stderr : bool [default: True]
+        Whether to clear stderr.
+    other : bool [default: True]
+        Whether to clear everything else that is not stdout/stderr
+        (e.g. figures,images,HTML, any result of display()).
+    """
+    from IPython.core.interactiveshell import InteractiveShell
+    InteractiveShell.instance().display_pub.clear_output(
+        stdout=stdout, stderr=stderr, other=other,
+    )

IPython/core/displaypub.py

@@ -104,6 +104,10 @@ def publish(self, source, data, metadata=None):
         if data.has_key('text/plain'):
             print(data['text/plain'], file=io.stdout)
 
+        def clear_output(self, stdout=True, stderr=True, other=True):
+            """Clear the output of the cell receiving output."""
+            pass
+
 
 def publish_display_data(source, data, metadata=None):
     """Publish data and metadata to all frontends.

IPython/frontend/html/notebook/static/js/codecell.js

@@ -364,9 +364,41 @@ var IPython = (function (IPython) {
     }
 
 
-    CodeCell.prototype.clear_output = function () {
-        this.element.find("div.output").html("");
-        this.outputs = [];
+    CodeCell.prototype.clear_output = function (stdout, stderr, other) {
+        var output_div = this.element.find("div.output");
+        if (stdout && stderr && other){
+            // clear all, no need for logic
+            output_div.html("");
+            this.outputs = [];
+            return;
+        }
+        // remove html output
+        // each output_subarea that has an identifying class is in an output_area
+        // which is the element to be removed.
+        if (stdout){
+            output_div.find("div.output_stdout").parent().remove();
+        }
+        if (stderr){
+            output_div.find("div.output_stderr").parent().remove();
+        }
+        if (other){
+            output_div.find("div.output_subarea").not("div.output_stderr").not("div.output_stdout").parent().remove();
+        }
+
+        // remove cleared outputs from JSON list:
+        for (var i = this.outputs.length - 1; i >= 0; i--){
+            var out = this.outputs[i];
+            var output_type = out.output_type;
+            if (output_type == "display_data" && other){
+                this.outputs.splice(i,1);
+            }else if (output_type == "stream"){
+                if (stdout && out.stream == "stdout"){
+                    this.outputs.splice(i,1);
+                }else if (stderr && out.stream == "stderr"){
+                    this.outputs.splice(i,1);
+                }
+            }
+        }
     };
 
 

IPython/frontend/html/notebook/static/js/notebook.js

@@ -627,7 +627,7 @@ var IPython = (function (IPython) {
         var cells = this.cells();
         for (var i=0; i<ncells; i++) {
             if (cells[i] instanceof IPython.CodeCell) {
-                cells[i].clear_output();
+                cells[i].clear_output(true,true,true);
             }
         };
         this.dirty = true;
@@ -733,7 +733,9 @@ var IPython = (function (IPython) {
             } else if (content.execution_state === 'dead') {
                 this.handle_status_dead();
             };
-        }
+        } else if (msg_type === 'clear_output') {
+            cell.clear_output(content.stdout, content.stderr, content.other);
+        };
     };
 
 
@@ -823,7 +825,7 @@ var IPython = (function (IPython) {
         var cell = that.selected_cell();
         var cell_index = that.find_cell_index(cell);
         if (cell instanceof IPython.CodeCell) {
-            cell.clear_output();
+            cell.clear_output(true, true, true);
             var code = cell.get_code();
             var msg_id = that.kernel.execute(cell.get_code());
             that.msg_cell_map[msg_id] = cell.cell_id;

IPython/zmq/zmqshell.py

@@ -80,6 +80,12 @@ def publish(self, source, data, metadata=None):
             parent=self.parent_header
         )
 
+    def clear_output(self, stdout=True, stderr=True, other=True):
+        content = dict(stdout=stdout, stderr=stderr, other=other)
+        self.session.send(
+            self.pub_socket, u'clear_output', content,
+            parent=self.parent_header
+        )
 
 class ZMQInteractiveShell(InteractiveShell):
     """A subclass of InteractiveShell for ZMQ."""