Method diff

src/danfojs-base/core/frame.ts:1474–1521

(other: DataFrame | Series | number[] | number, options?: { axis?: 0 | 1, inplace?: boolean })

    */
    diff(other: DataFrame | Series | number[] | number, options?: { axis?: 0 | 1, inplace?: boolean }): DataFrame
    diff(other: DataFrame | Series | number[] | number, options?: { axis?: 0 | 1, inplace?: boolean }): DataFrame | void {
        const { inplace, axis } = { inplace: false, axis: 1, ...options }

        if (this.$frameIsNotCompactibleForArithmeticOperation()) {
            throw Error("TypeError: diff operation is not supported for string dtypes");
        }

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

        if (other === 0) {
            return this;
        }

        if (typeof other === "number") {
            let origDF = this.copy() as DataFrame;
            if (axis === 0) {
                origDF = origDF.T;
            }
            const originalTensor = origDF.tensor.clone();
            const unit = new Array(originalTensor.shape[originalTensor.rank - 1]).fill(NaN);
            let diffArray: any[] = originalTensor.arraySync();
            if (other > 0) {
                for (let i = 0; i < other; i++) {
                    diffArray.unshift(unit);
                    diffArray.pop();
                }
            }
            else if (other < 0) {
                for (let i = 0; i > other; i--) {
                    diffArray.push(unit);
                    diffArray.shift();
                }
            }
            const diffTensor = tensorflow.tensor2d(diffArray, originalTensor.shape);
            const diffDF = this.$MathOps([originalTensor, diffTensor], "sub", inplace) as DataFrame;
            if (axis === 0) {
                return diffDF.T;
            }
            return diffDF;
        }

        if (other instanceof DataFrame || other instanceof Series) {
            const tensors = this.$getTensorsForArithmeticOperationByAxis(other, axis);
            return this.$MathOps(tensors, "sub", inplace);
        }
    }

    /**
     * Return the absolute value of elements in a DataFrame.