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Merge pull request #813 from jcb91/limit_output
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[limit_output] updates including allowing per-cell override of limit
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@jcb91
jcb91 committed Dec 3, 2016
2 parents 40fa980 + 7dc0e69 commit 3c290a2
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94 changes: 64 additions & 30 deletions src/jupyter_contrib_nbextensions/nbextensions/limit_output/main.js
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@@ -1,14 +1,11 @@
// Restrict output in a codecell to a maximum length

define([
'base/js/namespace',
'jquery',
'notebook/js/outputarea',
'base/js/dialog',
'notebook/js/codecell',
'services/config',
'base/js/utils'
], function(IPython, $, oa, dialog, cc, configmod, utils) {
], function(oa, cc, configmod, utils) {
"use strict";

var base_url = utils.get_body_data("baseUrl");
Expand All @@ -32,51 +29,88 @@ define([
}
};

function is_finite_number (n) {
n = parseFloat(n);
return !isNaN(n) && isFinite(n);
}

config.loaded.then(function() {
update_params();
var MAX_CHARACTERS = params.limit_output;
// sometimes limit_output metadata val can get stored as a string
params.limit_output = parseFloat(params.limit_output);

oa.OutputArea.prototype._handle_output = oa.OutputArea.prototype.handle_output;
var old_handle_output = oa.OutputArea.prototype.handle_output;
oa.OutputArea.prototype.handle_output = function (msg) {
if (msg.header.msg_type.match("stream|execute_result|display_data")) {
var count = 0;
var handled_msg_types = ['stream', 'execute_result', 'display_data'];
if (handled_msg_types.indexOf(msg.header.msg_type) < 0) {
return old_handle_output.apply(this, arguments);
}
else {
// get MAX_CHARACTERS from cell metadata if present, otherwise param
var MAX_CHARACTERS = params.limit_output;
var cell_metadata = this.element.closest('.cell').data('cell').metadata;
if (is_finite_number(cell_metadata.limit_output)) {
MAX_CHARACTERS = parseFloat(cell_metadata.limit_output);
}

// read the length of already-appended outputs from our data
var count = this.element.data('limit_output_count') || 0;
// update count with the length of this message
var old_count = count;
if (msg.header.msg_type === "stream") {
count = String(msg.content.text).length;
} else {
count = Math.max(
count += String(msg.content.text).length;
}
else {
count += Math.max(
(msg.content.data['text/plain'] === undefined) ? 0 : String(msg.content.data['text/plain']).length,
(msg.content.data['text/html'] === undefined) ? 0 : String(msg.content.data['text/html']).length )
(msg.content.data['text/html'] === undefined) ? 0 : String(msg.content.data['text/html']).length
);
}
if (count > MAX_CHARACTERS) {
console.log("limit_output: output", count, "exceeded", MAX_CHARACTERS, "characters. Further output muted.");
// save updated count
this.element.data('limit_output_count', count);

if (count <= MAX_CHARACTERS) {
return old_handle_output.apply(this, arguments);
}
// if here, we'd exceed MAX_CHARACTERS with addition of this message.
if (old_count <= MAX_CHARACTERS) {
// Apply truncated portion of this message
var to_add = MAX_CHARACTERS - old_count;
if (msg.header.msg_type === "stream") {
msg.content.text = msg.content.text.substr(0, MAX_CHARACTERS)
} else {
msg.content.text = msg.content.text.substr(0, to_add);
}
else {
if (msg.content.data['text/plain'] !== undefined) {
msg.content.data['text/plain'] = msg.content.data['text/plain'].substr(0, MAX_CHARACTERS);
msg.content.data['text/plain'] = msg.content.data['text/plain'].substr(0, to_add);
}
if (msg.content.data['text/html'] !== undefined) {
msg.content.data['text/html'] = msg.content.data['text/html'].substr(0, MAX_CHARACTERS);
msg.content.data['text/html'] = msg.content.data['text/html'].substr(0, to_add);
}
}
var limitmsg = {};
limitmsg.data = [];
old_handle_output.apply(this, arguments);

// display limit notification messages
console.log(
"limit_output: Maximum message size of", MAX_CHARACTERS,
"exceeded with", count, "characters. Further output muted."
);
// allow simple substitutions for output length for quick debugging
limitmsg.data['text/html'] = params.limit_output_message.replace("{limit_output_length}", MAX_CHARACTERS)
.replace("{output_length}", count);
this._handle_output(msg);
return this.append_display_data(limitmsg);
var limitmsg = params.limit_output_message.replace("{limit_output_length}", MAX_CHARACTERS)
.replace("{output_length}", count);
this.append_output({
"output_type": "display_data",
"metadata": {}, // included to avoid warning
"data": {"text/html": limitmsg},
});
}
}
return this._handle_output(msg);
};

cc.CodeCell.prototype._execute = cc.CodeCell.prototype.execute;
cc.CodeCell.prototype.execute = function() {
var old_clear_output = oa.OutputArea.prototype.clear_output;
oa.OutputArea.prototype.clear_output = function () {
// reset counter on execution.
this.output_area.count = 0;
this.output_area.drop = false;
return this._execute();
this.element.data('limit_output_count', 0);
return old_clear_output.apply(this, arguments);
};
});

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29 changes: 19 additions & 10 deletions src/jupyter_contrib_nbextensions/nbextensions/limit_output/readme.md
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@@ -1,30 +1,39 @@
Limit Output
============


Description
-----------
This extension limits the number of characters a codecell will output as text or HTML.
This also allows to interrupt endless loops of print commands.

This extension limits the number of characters a codecell will output as text
or HTML.
This also allows the interruption of endless loops of print commands.

[![Demo Video](http://img.youtube.com/vi/U26ujuPXf00/0.jpg)](https://youtu.be/U26ujuPXf00)

You can set the number of characters using the ConfigManager:

```Python
```python
from notebook.services.config import ConfigManager
cm = ConfigManager().update('notebook', {'limit_output': 1000})
```

or by using the [jupyter_nbextensions_configurator](https://github.com/Jupyter-contrib/jupyter_nbextensions_configurator)

The limit can also be set for an individual cell, using the cell's
`cell.metadata.limit_output`.


Internals
---------

Three types of messages are intercepted: `stream`, `execute_result`, `display_data`

For `stream`- type messages, the text string length is limited to `limit_output` number of characters
For other message types, `text/plain` and `text/html` content length is counted` and if either
exceeds `limit_output` charaters, will be truncated.
Three types of messages are intercepted: `stream`, `execute_result`, and
`display_data`. For `stream`-type messages, the text string length is limited
to `limit_output` number of characters.
For other message types, `text/plain` and `text/html` content length is
counted, and if either exceeds `limit_output` characters will be truncated to
`limit_output` number of characters.

The `limit_output_message` can be formatted to display the `limit_output` length and the current `output_length`,
respectively using the replacement fields `{limit_output_length}` and `{output_length}`.
The `limit_output_message` parameter can be formatted to display the
`limit_output` length and the current `output_length`, using the respective
replacement fields `{limit_output_length}` and `{output_length}`.

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