Method apply

src/danfojs-base/core/frame.ts:2535–2576

* Apply a function along an axis of the DataFrame. To apply a function element-wise, use `applyMap`. * Objects passed to the function are Series values whose * index is either the DataFrame’s index (axis=0) or the DataFrame’s columns (axis=1) * @param callable Function to apply to ea

(callable: any, options?: { axis?: 0 | 1 })

     * ```
    */
    apply(callable: any, options?: { axis?: 0 | 1 }): DataFrame | Series {
        const { axis } = { axis: 1, ...options }

        if ([0, 1].indexOf(axis) === -1) {
            throw Error(`ParamError: axis must be 0 or 1`);
        }

        const valuesForFunc = this.$getDataByAxisWithMissingValuesRemoved(axis)

        const result = valuesForFunc.map(row => {
            return callable(row)
        })

        if (axis === 0) {
            if (utils.is1DArray(result)) {
                return new Series(result, {
                    index: [...this.columns]
                })
            } else {
                return new DataFrame(result, {
                    index: [...this.columns],
                    columns: [...this.columns],
                    dtypes: [...this.dtypes],
                    config: { ...this.config }
                })
            }
        } else {
            if (utils.is1DArray(result)) {
                return new Series(result, {
                    index: [...this.index]
                })
            } else {
                return new DataFrame(result, {
                    index: [...this.index],
                    columns: [...this.columns],
                    dtypes: [...this.dtypes],
                    config: { ...this.config }
                })
            }
        }

    }

    /**
     * Apply a function to a Dataframe values element-wise.