symbolCode

Syntax

symbolCode(X)

Arguments

X is a vector/matrix of SYMBOL type.

Details

SYMBOL is a special STRING type used to store repetitive strings in DolphinDB. Internally, data of SYMBOL type is encoded into integers and stored as a dictionary. The internal encoding of an empty string is 0.

For each element in X, this function returns its internal encoding. The return value is of the same dimension as X.

It is recommended to use the SYMBOL type if there are a lot of duplicate values for a certain field such as device ID and stock symbol to improve storage efficiency.

Examples

$ a=symbol(`IBM`APPL)
$ symbolCode(a)
[1,2]

$ x=symbol(`MS`AMZN`AAPL`MS`IBM`AAPL)$3:2
$ symbolCode(x)

#0 #1
-- --
1  1
2  4
3  3