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[4]: 114 A DataFrame is a 2-dimensional data structure of rows and columns, similar to a spreadsheet, and analogous to a Python dictionary mapping column names (keys) to Series (values), with each Series sharing an index. [4]: 115 DataFrames can be concatenated together or "merged" on columns or indices in a manner similar to joins in SQL.
The format string used in strftime traces back to at least PWB/UNIX 1.0, released in 1977. Its date system command includes various formatting options. [2] [3] In 1989, the ANSI C standard is released including strftime and other date and time functions. [4]
In communications messages, a date-time group (DTG) is a set of characters, usually in a prescribed format, used to express the year, the month, the day of the month, the hour of the day, the minute of the hour, and the time zone, if different from Coordinated Universal Time (UTC).
Spark Core is the foundation of the overall project. It provides distributed task dispatching, scheduling, and basic I/O functionalities, exposed through an application programming interface (for Java, Python, Scala, .NET [16] and R) centered on the RDD abstraction (the Java API is available for other JVM languages, but is also usable for some other non-JVM languages that can connect to the ...
English-language media and commercial publications use Month-day-year in long format, but only Day-month-year format (both long and short numeric) are used in governmental and other English documents of official contexts. Sudan: No: Yes: No South Sudan: No: Yes: No Suriname: No: Yes: No Svalbard: No: Yes: No: Sweden: Yes: Sometimes: No
SQL was initially developed at IBM by Donald D. Chamberlin and Raymond F. Boyce after learning about the relational model from Edgar F. Codd [12] in the early 1970s. [13] This version, initially called SEQUEL (Structured English Query Language), was designed to manipulate and retrieve data stored in IBM's original quasirelational database management system, System R, which a group at IBM San ...
Name Original chapter Notability References Sadie Tanner Mossell Alexander, J.D., Ph.D. Gamma: 1919–1923. Mossell Alexander was the first African-American woman to receive a Ph.D. in the United States, the first woman to receive a law degree from the University of Pennsylvania Law School, one of the first Black women to receive a Phi Beta Kappa Key in the state of Pennsylvania, and the first ...
On January 1, 1913, Lieutenant Chester W. Nimitz was in command of the Atlantic Submarine Flotilla, with First Group consisting of submarines C-2, C-3, C-4, and C-5 under Lieutenant Lewis D. Causey, and Second Group consisting of submarines D-1, D-2, D-3, E-1, and E-2 under Lieutenant (junior grade) Claudius R. Hyatt. [1]