Data types
Introduction
Project Haystack defines a fixed set of data types called kinds, which are mapped to Python objects in Phable.
Map for singleton data types
Project Haystack | Phable |
---|---|
Marker |
phable.Marker |
NA |
phable.NA |
Remove |
phable.Remove |
Map for scalar atomic data types
Project Haystack | Phable |
---|---|
Bool |
bool |
Number |
phable.Number |
Str |
str |
Uri |
phable.Uri |
Ref |
phable.Ref |
Symbol |
phable.Symbol |
Date |
datetime.date |
Time |
datetime.time |
DateTime |
datetime.datetime |
Coord |
phable.Coord |
XStr |
phable.XStr |
Note: Phable's datetime.datetime
must be timezone aware to represent Project
Haystack's DateTime
.
Map for collection data types
Project Haystack | Phable |
---|---|
List |
list |
Dict |
dict |
Grid |
phable.Grid |
Data Types in Phable Only
As a convenience, Phable defines these data types, which are not defined in Project Haystack:
phable.DateRange
phable.DateTimeRange
Marker
Marker
data type defined by Project Haystack
here. Marker
is a
singleton used to create "label" tags.
Example:
from phable.kinds import Marker
meter_equip = {"meter": Marker(), "equip": Marker()}
Source code in phable/kinds.py
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|
NA
NA
data type defined by Project Haystack
here. NA
is a
singleton to indicate a data value that is not available. In Project Haystack it is
most often used in historized data to indicate a timestamp sample is in error.
Source code in phable/kinds.py
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|
Remove
Remove
data type defined by Project Haystack
here. Remove
is a
singleton used in a dict
to indicate removal of a tag.
Source code in phable/kinds.py
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|
Number
dataclass
Number
data type defined by Project Haystack
here.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
val |
float
|
Floating point value. |
required |
unit |
str | None
|
Optional unit of measurement defined in Project Haystack's standard unit database here. Note: Phable does not validate a defined unit at this time. |
None
|
Source code in phable/kinds.py
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Uri
dataclass
Uri
data type defined by Project Haystack
here.
Example:
from phable.kinds import Uri
uri = Uri("http://project-haystack.org/")
Parameters:
Name | Type | Description | Default |
---|---|---|---|
val |
str
|
Universal Resource Identifier according to RFC 3986. |
required |
Source code in phable/kinds.py
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|
Ref
dataclass
Ref
data type defined by Project Haystack
here.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
val |
str
|
Unique identifier for an entity. |
required |
dis |
str | None
|
Optional human display name. |
None
|
Source code in phable/kinds.py
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|
Symbol
dataclass
Symbol
data type defined by Project Haystack
here.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
val |
str
|
def identifier. Consists of only ASCII letters, digits, underbar, colon, dash, period, or tilde. |
required |
Source code in phable/kinds.py
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|
Coord
dataclass
Coord
data type defined by Project Haystack
here.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
lat |
decimal.Decimal
|
Latitude represented in decimal degrees. |
required |
lng |
decimal.Decimal
|
Longitude represented in decimal degrees. |
required |
Source code in phable/kinds.py
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|
XStr
dataclass
XStr
data type defined by Project Haystack
here.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
type |
str
|
Type name that follows Project Haystack's tag naming rules, except it must start with an ASCII uppercase letter (A-Z). |
required |
val |
str
|
String encoded value. |
required |
Source code in phable/kinds.py
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|
Grid
dataclass
Grid
data type defined by Project Haystack
here.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
meta |
dict[str, typing.Any]
|
Metadata for the entire |
required |
cols |
list[dict[str, typing.Any]]
|
Metadata for columns within the |
required |
rows |
list[dict[str, typing.Any]]
|
Row data for |
required |
Source code in phable/kinds.py
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|
get_df_meta
get_df_meta()
Gets metadata for a DataFrame describing data from a Grid
.
In the returned dictionary:
- Value for
meta
key is data used in Grid'smeta
attribute. - Value for
cols
key is data used in Grid'scols
attribute.
Returns:
Type | Description |
---|---|
dict[str, dict[str, typing.Any] | list[dict[str, typing.Any]]]
|
Dictionary with keys |
Source code in phable/kinds.py
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to_grid
staticmethod
to_grid(rows, meta=None)
Creates a Grid
using row data and optional metadata.
If parameters include history data, assumes the history rows are in
chronological order to establish hisStart
and hisEnd
in meta
.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
rows |
dict[str, typing.Any] | list[dict[str, typing.Any]]
|
Row data for |
required |
meta |
dict[str, typing.Any] | None
|
Optional metadata for the entire |
None
|
Source code in phable/kinds.py
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to_pandas
to_pandas()
Converts rows in the Grid
to a Pandas DataFrame.
Requires Phable's optional Pandas dependency to be installed.
For Grids with rows that do not have history data, Phable defined data types
are passed as the data
input to the DataFrame.
For Grids with rows that have history data, an opinionated mashing process is
applied to data passed to the DataFrame's data
input:
- Phable's
NA
objects are converted toNone
- Missing column values are converted to
None
Number
objects are converted to unitlessfloat
values
The resultant Pandas DataFrame's data types are converted to the pyarrow
data
format.
Notes:
- This method is experimental and subject to change.
- This method assumes all
Number
objects in a given column has the same unit.
Example:
from datetime import datetime, timedelta
from phable import Grid, Number
ts_now = datetime.now()
data = [
{"ts": ts_now - timedelta(minutes=30), "val": Number(30, "kW")},
{"ts": ts_now, "val": Number(38, "kW")},
]
data = Grid.to_grid(data)
df = data.to_pandas()
Source code in phable/kinds.py
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to_pandas_all
to_pandas_all()
Returns a tuple: (Grid.get_df_meta(), Grid.to_pandas())
Example:
from datetime import datetime, timedelta
from phable import Grid, Number
ts_now = datetime.now()
data = [
{"ts": ts_now - timedelta(minutes=30), "val": Number(30, "kW")},
{"ts": ts_now, "val": Number(38, "kW")},
]
data = Grid.to_grid(data)
df_meta, df = data.to_pandas_all()
Source code in phable/kinds.py
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|
to_polars
to_polars()
Converts rows in the Grid
to a Polars DataFrame.
Requires Phable's optional Polars dependency to be installed.
For Grids with rows that do not have history data, Phable defined data types
are passed as the data
input to the DataFrame.
For Grids with rows that have history data, an opinionated mashing process is
applied to data passed to the DataFrame's data
input:
- Phable's
NA
objects are converted toNone
- Missing column values are converted to
None
Number
objects are converted to unitlessfloat
values
Notes:
- This method is experimental and subject to change.
- This method assumes all
Number
objects in a given column has the same unit.
Example:
from datetime import datetime, timedelta
from phable import Grid, Number
ts_now = datetime.now()
data = [
{"ts": ts_now - timedelta(minutes=30), "val": Number(30, "kW")},
{"ts": ts_now, "val": Number(38, "kW")},
]
data = Grid.to_grid(data)
df = data.to_polars()
Source code in phable/kinds.py
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to_polars_all
to_polars_all()
Returns a tuple: (Grid.get_df_meta(), Grid.to_polars())
Example:
from datetime import datetime, timedelta
from phable import Grid, Number
ts_now = datetime.now()
data = [
{"ts": ts_now - timedelta(minutes=30), "val": Number(30, "kW")},
{"ts": ts_now, "val": Number(38, "kW")},
]
data = Grid.to_grid(data)
df_meta, df = data.to_polars_all()
Source code in phable/kinds.py
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|
DateRange
dataclass
DateRange
data type, defined by Phable
, describes a time range using dates.
Note: Project Haystack does not define a kind for DateRange
.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
start |
datetime.date
|
Midnight of the start date (inclusive) for the range. |
required |
end |
datetime.date
|
Midnight of the end date (exclusive) for the range. |
required |
Source code in phable/kinds.py
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|
DateTimeRange
dataclass
DateTimeRange
data type, defined by Phable
, describes a time range using
date, time, and timezone information.
Note: Project Haystack does not define a kind for DateTimeRange
.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
start |
datetime.datetime
|
Start timestamp (inclusive) which is timezone aware. |
required |
end |
datetime.datetime | None
|
Optional end timestamp (exclusive) which is timezone aware. If end is undefined, then assume end to be when the last data value was recorded. |
None
|
Source code in phable/kinds.py
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