sortBy!

sortBy!(table, sortColumns, [sortDirections])

table is a table object. It can be a partitioned or unpartitioned in-memory table.

sortColumns can be a string scalar/vector indicating the columns based on which the table will be sorted. It can also be a piece of metacode with an expression.

sortDirections (optional) is a Boolean scalar/vector indicating the sorting directions for the sorting columns. 1 means ascending and 0 means descending. If sortColumns is a vector and sortDirections is a scalar, the sortDirections applies to all the sorting columns.

Sort a table in-place based on the specified columns and directions. If the table is a partitioned table, the sorting is conducted within each partition, not on the entire table.

This operation is executed in parallel if the table is a partitioned table and the parallel processing feature is enabled (when the configuration parameter localExcutors > 0).

Sort an unpartitioned table:

n=20000000
trades=table(rand(`IBM`MSFT`GM`C`YHOO`GOOG,n) as sym, 2000.01.01+rand(365,n) as date, 10.0+rand(2.0,n) as price, rand(1000,n) as qty);
trades.sortBy!(`sym`date, [0,1]);

Sort a partitioned table:

workDir = "C:/DolphinDB/Data"
if(!exists(workDir)) mkdir(workDir)
trades.saveText(workDir + "/trades.txt")
db = database(workDir + "/trade",VALUE,`IBM`MSFT`GM`C`YHOO`GOOG)
db.loadTextEx("trades","sym", workDir + "/trades.txt")
trades = db.loadTable("trades",`IBM`GM`YHOO,1)
trades.sortBy!(`date)
trades.sortBy!(`date, false)
trades.sortBy!(`date`qty, false)
trades.sortBy!(`date`qty, false true)
trades.sortBy!(<qty*price>)
trades.sortBy!(<[date, sym]>)
trades.sortBy!(<[sym, qty*price]>, true false)