Method substring

src/danfojs-base/core/strings.ts:642–660

(startIndex = 0, endIndex = 1, options?: { inplace?: boolean })

    */
    substring(startIndex: number, endIndex: number, options?: { inplace?: boolean }): Series
    substring(startIndex = 0, endIndex = 1, options?: { inplace?: boolean }): Series | void {
        const { inplace } = { inplace: false, ...options }
        const newArr: Array<string | number> = [];
        this.values.map((val) => {
            if (utils.isEmpty(val)) {
                newArr.push(NaN);
            } else {
                newArr.push(`${String(val).substring(startIndex, endIndex)}`);
            }
        });
        if (inplace) {
            this.series.$setValues(newArr as ArrayType1D)
            this.series.print()
        } else {
            const sf = this.series.copy()
            sf.$setValues(newArr as ArrayType1D)
            return sf;
        }
    }

    /**
      * Removes whitespace from both ends of a string