Merge branch 'danfo/typescript' of https://github.com/javascriptdata/danfojs into danfo/typescript

Author: risenW

src/danfojs-base/core/frame.ts

@@ -1324,14 +1324,15 @@ export default class DataFrame extends NDframe implements DataFrameInterface {
     addColumn(
         column: string,
         values: Series | ArrayType1D,
-        options?: { inplace?: boolean }
+        options?: { inplace?: boolean, atIndex?: number }
     ): DataFrame
     addColumn(
         column: string,
         values: Series | ArrayType1D,
-        options?: { inplace?: boolean }
+        options?: { inplace?: boolean, atIndex?: number }
     ): DataFrame | void {
         const { inplace } = { inplace: false, ...options };
+        const atIndex = typeof options?.atIndex !== "undefined" ? options.atIndex : this.columns.length
 
         if (!column) {
             throw new Error("ParamError: column must be specified")
@@ -1362,19 +1363,24 @@ export default class DataFrame extends NDframe implements DataFrameInterface {
             const oldValues = this.$data
             for (let i = 0; i < oldValues.length; i++) {
                 const innerArr = [...oldValues[i]] as ArrayType1D
-                innerArr.push(colunmValuesToAdd[i])
+                innerArr.splice(atIndex, 0, colunmValuesToAdd[i])
                 newData.push(innerArr)
             }
 
             if (inplace) {
                 this.$setValues(newData, true, false)
-                this.$setColumnNames([...this.columns, column]);
+                let columns = [...this.columns]
+                columns.splice(atIndex, 0, column)
+                this.$setColumnNames(columns)
                 this.$setInternalColumnDataProperty(column);
 
             } else {
+                let columns = [...this.columns]
+                columns.splice(atIndex, 0, column)
+                
                 const df = new DataFrame(newData, {
                     index: [...this.index],
-                    columns: [...this.columns, column],
+                    columns: columns,
                     dtypes: [...this.dtypes, utils.inferDtype(colunmValuesToAdd)[0]],
                     config: { ...this.$config }
                 })

src/danfojs-base/shared/types.ts

@@ -246,7 +246,8 @@ export interface DataFrameInterface extends NDframeInterface {
         column: string,
         values: Series | ArrayType1D,
         options?: {
-            inplace?: boolean
+            inplace?: boolean,
+            atIndex?: number
         }
     ): DataFrame | void
     groupby(column: [string, string]): any //Update to GroupBy class later

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

@@ -144,6 +144,15 @@ describe("DataFrame", function () {
             assert.deepEqual(df["val_count"].values, [1, 2, 3, 4]);
             assert.deepEqual(df["val_sum"].values, [20.3, 30.456, 40.90, 90.1]);
         });
+        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;
+            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"]);
+            assert.deepEqual(newdf.index, [0, 1, 2, 3]);
+        });
     })
 
     describe("drop", function () {