Method nUnique

src/danfojs-base/core/frame.ts:2909–2927

* Return the number of unique elements in a column, across the specified axis. * To get the values use `.unique()` instead. * @param axis The axis to count unique elements across. Defaults to 1 * @example * ``` * const df = new DataFrame([[1, 2], [3, 4], [1, 2], [5, 6]], {

(axis: 0 | 1 = 1)

     * 
    */
    nUnique(axis: 0 | 1 = 1): Series {
        if ([0, 1].indexOf(axis) === -1) {
            throw Error(`ParamError: axis must be 0 or 1`);
        }
        const data = this.$getDataArraysByAxis(axis)
        const newData = data.map(row => new Set(row).size)

        if (axis === 0) {
            return new Series(newData, {
                index: [...this.columns],
                dtypes: ["int32"]
            })
        } else {
            return new Series(newData, {
                index: [...this.index],
                dtypes: ["int32"]
            })
        }
    }

    /**
     * Renames a column or index to specified value.