Method dropDuplicates

src/danfojs-base/core/series.ts:1697–1740

(options?: { keep?: "first" | "last", inplace?: boolean })

    */
    dropDuplicates(options?: { keep?: "first" | "last", inplace?: boolean }): Series
    dropDuplicates(options?: { keep?: "first" | "last", inplace?: boolean }): Series | void {
        const { keep, inplace } = { keep: "first", inplace: false, ...options }

        if (!(["first", "last"].includes(keep))) {
            throw Error(`Params Error: Keep must be one of 'first' or 'last'`);
        }

        let dataArr: ArrayType1D
        let newArr: ArrayType1D = [];
        let oldIndex: Array<string | number>
        let newIndex: Array<string | number> = [];

        if (keep === "last") {
            dataArr = (this.values as ArrayType1D).reverse();
            oldIndex = this.index.reverse();
        } else {
            dataArr = (this.values as ArrayType1D)
            oldIndex = this.index;
        }

        dataArr.forEach((val, i) => {
            if (!newArr.includes(val)) {
                newIndex.push(oldIndex[i]);
                newArr.push(val);
            }
        });

        if (keep === "last") {
            //re-reversed the array and index to its true order
            newArr = newArr.reverse();
            newIndex = newIndex.reverse();
        }

        if (inplace) {
            this.$setValues(newArr, false)
            this.$setIndex(newIndex)
        } else {
            const sf = this.copy();
            sf.$setValues(newArr, false)
            sf.$setIndex(newIndex)
            return sf;
        }

    }

    /**
     * Cast Series to specified data type