Histories¶

Histories are a really important part of building data. Pyhaystack allows retrieving histories as zinc grid, pandas series or pandas Dataframe depending on your needs.

Range¶

rng (range) can be one of the following [ref : his_read]

“today”
“yesterday”
“{date}”
“{date},{date}”
“{dateTime},{dateTime}”
“{dateTime}” // anything after given timestamp

Zinc Date and time format¶

[ref : http://project-haystack.org/doc/Zinc]

<date> := YYYY-MM-DD
<time> := hh:mm:ss.FFFFFFFFF
<dateTime> := YYYY-MM-DD’T’hh:mm:ss.FFFFFFFFFz zzzz

Retrieve simple grid¶

session.his_read('S.SERVISYS.Bureau-Christian.ZN~2dT', rng='today').result

Retrieve a Pandas Series¶

For more details about Pandas : pandas_datastructure

session.his_read_series('S.SERVISYS.Bureau-Christian.ZN~2dT', rng= 'today').result

Retrieve a Pandas Dataframe¶

In the following example, we will retrive all the historical value from ‘today’ for all zone temperature sensors.

znt = session.find_entity(filter_expr='sensor and zone and temp').result
b = session.his_read_frame(znt, rng= 'today').result
b

We use find_entity first, then we call his_read_frame over the result.