Fill gaps in pivot table

[cpalbrecht]

I have the following pivot table:

Each row represent a specific state. The states are grouped. Each column is a timestamp.

Let's take the group "operational_status". At 09:52:30.273 the operational state changed to converter, isolation_monitor and safety_relay. And at 09:52:39.784 the state changed again to converter and safety_relay.

Now I want to have the first state change for each timestamp until the next state change and so on. For that example I want to have the first state (converter, isolation_monitor and safety_relay) for each red marked column.

[Digvijay_Singh]

If these red mark values are null then may be something like this in the expression of values shown for timestamp, I assume timestamp value is a kind of flag value, helping to color specific cells.

if(len(timestampvalue)=0,before(timestampvalue),timestampvalue)