bfill

bfill(obj, [limit])

obj is a vector/matrix/table.

limit (optional) is a positive integer indicating the number of NULL values to be filled.

If obj is a vector: back fill the NULL values in obj with the next non-NULL value.

If obj is a matrix or a table: back fill the NULL values in each column of obj with the next non-NULL value.

This operation creates a new object and does not change the input obj. Function bfill! changes the input obj.

x=1 2 3 NULL NULL NULL 4 5 6
x.bfill();
// output
[1,2,3,4,4,4,4,5,6]

x=1 2 3 NULL NULL NULL 4 5 6
x.bfill(1);
// output
[1,2,3,,,4,4,5,6]

x.bfill!(2);
x;
// output
[1,2,3,,4,4,4,5,6]

date=[2012.06.12,2012.06.12,2012.06.13,2012.06.14,2012.06.15]
sym=["IBM","MSFT","IBM","MSFT","MSFT"]
price=[,,26.56,,50.76]
qty=[,,4500,5600,6800]
timestamp=[09:34:07,09:35:26,09:36:42,09:36:51,09:36:59]
t=table(date,timestamp,sym,price,qty)
t;

t.bfill()

select date, timestamp, sym, price.bfill() as price, qty.bfill() as qty from t context by sym;