diff --git a/src/frontend/core/Randomize.js b/src/frontend/core/Randomize.js
new file mode 100644
index 0000000000000000000000000000000000000000..e6b35bb376649294cc40f2723989234b78e72d31
--- /dev/null
+++ b/src/frontend/core/Randomize.js
@@ -0,0 +1,47 @@
+const integer = (min = 1, max = 9) => {
+  return (Math.random() * (max - min + 1) | 0) + min;
+};
+
+const array1D = (N, options) => {
+  return array2D(1, N, options)[0];
+};
+
+const array2D = (N = 10, M = 10, options = {}) => {
+  const { sorted = false, min, max } = options;
+  const D = [];
+  for (let i = 0; i < N; i++) {
+    D.push([]);
+    for (let j = 0; j < M; j++) {
+      D[i].push(integer(min, max));
+    }
+    if (sorted) D[i].sort((a, b) => a - b);
+  }
+  return D;
+};
+
+const graph = (N = 5, options = {}) => {
+  const { directed = true, weighted = false, ratio = .3, min, max } = options;
+  const G = new Array(N);
+  for (let i = 0; i < N; i++) G[i] = new Array(N);
+  for (let i = 0; i < N; i++) {
+    G[i][i] = 0;
+    if (directed) {
+      for (let j = 0; j < N; j++) {
+        if (i === j) continue;
+        G[i][j] = Math.random() < ratio ? weighted ? integer(min, max) : 1 : 0;
+      }
+    } else {
+      for (let j = 0; j < i; j++) {
+        G[i][j] = G[j][i] = Math.random() < ratio ? weighted ? integer(min, max) : 1 : 0;
+      }
+    }
+  }
+  return G;
+};
+
+export default {
+  integer,
+  array1D,
+  array2D,
+  graph,
+};
\ No newline at end of file
diff --git a/src/frontend/core/datas/Array2DData.js b/src/frontend/core/datas/Array2DData.js
index d9eddb6967daabd9227991ce9981ac5dd242dbaa..a2feeeb9d1e290b4531756ed8ff1dca96752bad6 100644
--- a/src/frontend/core/datas/Array2DData.js
+++ b/src/frontend/core/datas/Array2DData.js
@@ -18,7 +18,7 @@ class Array2DData extends Data {
     super.set();
   }
 
-  notify(x, y, v) {
+  notify(x, y, v = this.data[x][y].value) {
     this.data[x][y].value = v;
     this.data[x][y].notified = true;
     this.render();
diff --git a/src/frontend/core/datas/GraphData.js b/src/frontend/core/datas/GraphData.js
index d77dab65c9368a8ce7be9f677c85d4b4c54998c7..435e78dd919de3f1ca8e9dd89cd0fcf64cb30abc 100644
--- a/src/frontend/core/datas/GraphData.js
+++ b/src/frontend/core/datas/GraphData.js
@@ -108,12 +108,12 @@ class Graph {
   }
 
   addNode(id, weight, visited, x = 0, y = 0) {
-    if (this.findNode(id)) throw new Error(`Node '${id}' is already added.`);
+    if (this.findNode(id)) return;
     this.nodes.push({ id, weight, visited, x, y });
   }
 
   addEdge(source, target, weight, visited) {
-    if (this.findEdge(source, target)) throw new Error(`Edge from '${source}' to '${target}' is already added.`);
+    if (this.findEdge(source, target)) return;
     this.edges.push({ source, target, weight, visited });
   }
 
diff --git a/src/frontend/core/index.js b/src/frontend/core/index.js
index 4197bf05964e754726366f1f79910a6b44945ff2..7f90fed1fb315cc1a16484cf74e957eca6eaf65e 100644
--- a/src/frontend/core/index.js
+++ b/src/frontend/core/index.js
@@ -1,2 +1,3 @@
+export { default as Randomize } from './Randomize';
 export { default as Seed } from './Seed';
 export { default as tracerManager } from './tracerManager';
\ No newline at end of file
diff --git a/src/frontend/core/tracerManager.jsx b/src/frontend/core/tracerManager.jsx
index 1208a6cbb2864beac561b9289e3ddac4a49fe39d..7d7e7e2ccddd24cc552270334bc5875b68479fce 100644
--- a/src/frontend/core/tracerManager.jsx
+++ b/src/frontend/core/tracerManager.jsx
@@ -1,5 +1,5 @@
 import React from 'react';
-import { Seed } from '/core';
+import { Randomize, Seed } from '/core';
 import * as Tracers from '/core/tracers';
 import { Tracer } from '/core/tracers';
 import * as Datas from '/core/datas';
@@ -8,6 +8,7 @@ import { Array1DRenderer, Array2DRenderer, ChartRenderer, GraphRenderer, LogRend
 
 Object.assign(window, Tracers);
 Object.assign(window, Datas);
+Object.assign(window, { Randomize });
 
 class TracerManager {
   constructor() {
diff --git a/src/frontend/core/tracers/Tracer.js b/src/frontend/core/tracers/Tracer.js
index 846e2e9e966eac2603ea121601d411765b2f210f..5374a9ff994d8b2c571d572d27bb150dee7bb033 100644
--- a/src/frontend/core/tracers/Tracer.js
+++ b/src/frontend/core/tracers/Tracer.js
@@ -1,5 +1,9 @@
 class Tracer {
   constructor(title = this.constructor.name, options = {}) {
+    if (typeof title === 'object') {
+      options = title;
+      title = this.constructor.name;
+    }
     this.key = Tracer.seed.addTracer(this.constructor.name, title, options);
     this.register(
       'reset',