saveText

saveText(obj, filename, [delimiter=','], [append=false], [header=true], [bom=''])

obj can be a table/matrix/vector/metacode of SQL statements. When obj is the metacode of SQL statements, multiple workers are allocated to read the data concurrently, and the data is written to the file with another worker. In other cases, data queries and writes are handled by the current worker.

filename is a string indicating the absolute path and name of the output file. Currently the output file can only be saved in .csv format.

delimiter (optional) is the table column separator. The system uses comma as the default delimiter.

append (optional) is a Boolean value indicating whether to append to (true) or overwrite (false) the output file if it exists already.

header (optional) is a BOOLEAN indicating whether to save the column names in the output file when obj is a table. The default value is true. Please note that this parameter has no effect when this command is used for appending data to an existing non-empty file (i.e., when append = true).

bom (optional) is a case-insensitive STRING scalar that determines whether to include Byte order mark (BOM) in output CSV files. Currently, only "UTF-8" is supported. It defaults to ' '.

Save DolphinDB variables or data queried by SQL statement as a text file on disk. Compared with saveTable, saveText requires more disk space and time.

Example 1

n=20000000
syms=`IBM`C`MS`MSFT`JPM`ORCL`GE`EBAY`GOOG`FORD`GS
timestamp=09:30:00+rand(18000,n)
sym=rand(syms,n)
qty=100*(1+rand(100,n))
price=5.0+rand(100.0,n)
t1=table(timestamp,sym,qty,price);

timer saveText(t1, "c:/test/trades.txt");
// output
Time elapsed: 191488 ms

Example 2

n=100
t1=table(1..n as id, rand(1000, n) as x)
saveText(t1, "C:/DolphinDB/Data/t.csv",,1)
t2=table((n+1)..(2*n) as id, rand(1000, n) as x)
saveText(t2, "C:/DolphinDB/Data/t.csv",,1)
t = loadText("C:/DolphinDB/Data/t.csv")
select count(*) from t;
// output
200

Example 3 Save a DFS table as a text file

if(existsDatabase("dfs://testdb")){

  dropDatabase("dfs://testdb")
}
n=3000
ticker = rand(`MSFT`GOOG`FB`ORCL`IBM`PPT`AZH`ILM`ANZ,n);
id = rand(`A`B`C, n)
x=rand(1.0, n)
t=table(ticker, id, x)
db=database(directory="dfs://testdb", partitionType=HASH, partitionScheme=[STRING, 5])
pt = db.createPartitionedTable(t, `pt, `ticker)
pt.append!(t)

saveText(<select * from pt>, "/home/data/pt.txt")