Fixed subsetting bug after rename

Author: risenW

src/danfojs-base/core/frame.ts

@@ -2184,8 +2184,10 @@ export default class DataFrame extends NDframe implements DataFrameInterface {
         }
 
         if (axis === 1) {
+            const colsAdded: string[] = [];
             const newColumns = this.columns.map(col => {
                 if (mapper[col] !== undefined) {
+                    colsAdded.push(mapper[col]);
                     return mapper[col]
                 } else {
                     return col
@@ -2194,6 +2196,9 @@ export default class DataFrame extends NDframe implements DataFrameInterface {
 
             if (inplace) {
                 this.$setColumnNames(newColumns)
+                for (const col of colsAdded) {
+                    this.$setInternalColumnDataProperty(col);
+                }
             } else {
                 return new DataFrame([...this.values], {
                     index: [...this.index],
@@ -2472,7 +2477,7 @@ export default class DataFrame extends NDframe implements DataFrameInterface {
         if (utils.isBrowserEnv()) {
             const plt = new PlotlyLib(this, divId);
             return plt;
-        }else{
+        } else {
             throw new Error("Not supported in NodeJS");
         }
     }

src/danfojs-base/shared/utils.ts

@@ -64,7 +64,7 @@ export default class Utils {
      * @returns 
      */
     isObject(value: any): boolean {
-        return typeof value === "object" && value.constructor && value.constructor.name === "Object";
+        return value && typeof value === "object" && value.constructor && value.constructor.name === "Object";
     }
 
     /**

src/danfojs-browser/tests/core/frame.test.js

@@ -2279,6 +2279,29 @@ describe("DataFrame", function () {
       assert.deepEqual(df.index, res);
 
     });
+
+    it("Get new column via subseting works after rename (inplace)", function () {
+      let data = {
+        "A": [ -20, 30, 47.3 ],
+        "B": [ 34, -4, 5 ],
+        "C": [ 20, 2, 30 ]
+      };
+      let df = new dfd.DataFrame(data);
+      df.rename({ "A": "new_name" }, { inplace: true });
+      df["new_name"].print();
+      assert.deepEqual(df["new_name"].values, data["A"]);
+    });
+
+    it("Get new column via subseting works after rename (not-inplace)", function () {
+      let data = {
+        "A": [ -20, 30, 47.3 ],
+        "B": [ 34, -4, 5 ],
+        "C": [ 20, 2, 30 ]
+      };
+      let df = new dfd.DataFrame(data);
+      let new_df = df.rename({ "A": "new_name" });
+      assert.deepEqual(new_df["new_name"].values, data["A"]);
+    });
   });
 
   describe("sortIndex", function () {

src/danfojs-node/test/core/frame.test.ts

@@ -148,7 +148,7 @@ describe("DataFrame", function () {
         it("Add new array values to DataFrame works", function () {
             let data = { alpha: ["A", "B", "C", "D"], val_count: [1, 2, 3, 4], val_sum: [20.3, 30.456, 40.90, 90.1] };
             let df = new DataFrame(data);
-            const newdf = df.addColumn("new_column", ["a", "b", "c", "d"], {atIndex: 0}) as DataFrame;
+            const newdf = df.addColumn("new_column", ["a", "b", "c", "d"], { atIndex: 0 }) as DataFrame;
             assert.deepEqual(newdf["new_column"].values, ["a", "b", "c", "d"]);
             assert.deepEqual(newdf.columns, ["new_column", "alpha", "val_count", "val_sum"]);
             assert.deepEqual(newdf.dtypes, ["string", "int32", "float32", "string"]);
@@ -2303,6 +2303,28 @@ describe("DataFrame", function () {
             assert.deepEqual(df.index, res);
 
         });
+        it("Get new column via subseting works after rename (inplace)", function () {
+            let data = {
+                "A": [-20, 30, 47.3],
+                "B": [34, -4, 5],
+                "C": [20, 2, 30]
+            };
+            let df = new DataFrame(data);
+            df.rename({ "A": "new_name" }, { inplace: true });
+            df["new_name"].print();
+            assert.deepEqual(df["new_name"].values, data["A"]);
+        });
+
+        it("Get new column via subseting works after rename (not-inplace)", function () {
+            let data = {
+                "A": [-20, 30, 47.3],
+                "B": [34, -4, 5],
+                "C": [20, 2, 30]
+            };
+            let df = new DataFrame(data);
+            let new_df = df.rename({ "A": "new_name" });
+            assert.deepEqual(new_df["new_name"].values, data["A"]);
+        });
     });
 
     describe("sortIndex", function () {