. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 840 65 分隔符文件 841 66 分布式计算 847 66.1 Cluster Manager Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Julia 还拥有以下 优势： • 采用 MIT 许可证：免费又开源 • 用户自定义类型的速度与兼容性和内建类型一样好 • 无需特意编写向量化的代码：非向量化的代码就很快 • 为并行计算和分布式计算设计 • 轻量级的“绿色”线程：协程 • 低调又牛逼的类型系统 • 优雅、可扩展的类型转换和类型提升 • 对 Unicode 的有效支持，包括但不限于 UTF-8 • 直接调用 C 函数，无需封装或调用特别的 Julia 支持表示统计意义上的缺失值，即某个变量在观察中没有可用值，但在理论上存在有效值的情 况。缺失值由 missing 对象表示，该对象是 Missing 类型的唯一实例。missing 等价于 SQL 中的 NULL 以及 R 中的 NA，并在大多数情况下表现得与它们一样。 21.1 缺失值的传播 missing values propagate automatically when passed

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situa�ons. 27.1 Propaga�on of Missing Values The behavior following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract defini�on actually corresponds to a rela�vely natural behavior which is Nothing} arguments or fields. To represent missing data in the sta�s�cal sense (NA in R or NULL in SQL), use the missing object. See the Missing Values sec�on for more details. The empty tuple (()) is

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situa�ons. 27.1 Propaga�on of Missing Values The behavior following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract defini�on actually corresponds to a rela�vely natural behavior which is Nothing} arguments or fields. To represent missing data in the sta�s�cal sense (NA in R or NULL in SQL), use the missing object. See the Missing Values sec�on for more details. The empty tuple (()) is

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situa�ons. 27.1 Propaga�on of Missing Values The behavior following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract defini�on actually corresponds to a rela�vely natural behavior which is Nothing} arguments or fields. To represent missing data in the sta�s�cal sense (NA in R or NULL in SQL), use the missing object. See the Missing Values sec�on for more details. The empty tuple (()) is

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situa�ons. 28.1 Propaga�on of Missing Values The behavior following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract defini�on actually corresponds to a rela�vely natural behavior which is Nothing} arguments or fields. To represent missing data in the sta�s�cal sense (NA in R or NULL in SQL), use the missing object. See the Missing Values sec�on for more details. The empty tuple (()) is

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 27.1 Propagation of Missing Values The behavior following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract definition actually corresponds to a relatively natural behavior which is Nothing} arguments or fields. To represent missing data in the statistical sense (NA in R or NULL in SQL), use the missing object. See the Missing Values section for more details. The empty tuple (()) is

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situa�ons. 29.1 Propaga�on of Missing Values The behavior following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract defini�on actually corresponds to a rela�vely natural behavior which is Nothing} arguments or fields. To represent missing data in the sta�s�cal sense (NA in R or NULL in SQL), use the missing object. See the Missing Values sec�on for more details. The empty tuple (()) is

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 20.1 Propagation of Missing Values missing following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract definition actually corresponds to a relatively natural behavior which is Nothing} arguments or fields. To represent missing data in the statistical sense (NA in R or NULL in SQL), use the missing object. See the Missing Values section for more details. In some languages, the

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 20.1 Propagation of Missing Values missing following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract definition actually corresponds to a relatively natural behavior which is Nothing} arguments or fields. To represent missing data in the statistical sense (NA in R or NULL in SQL), use the missing object. See the Missing Values section for more details. In some languages, the

missing object, which is the singleton instance of the type Missing. missing is equivalent to NULL in SQL and NA in R, and behaves like them in most situations. 20.1 Propagation of Missing Values missing following the well-established rules of three-valued logic which are also implemented by NULL in SQL and NA in R. This abstract definition actually corresponds to a relatively natural behavior which is Nothing} arguments or fields. To represent missing data in the statistical sense (NA in R or NULL in SQL), use the missing object. See the Missing Values section for more details. In some languages, the