Python datatype to Tag datatype

Ignition
1

Is there a function out there that will take a python datatype and return a tag datatype? I want to automate turning python objects into tags.

2

@pturmel said:

Is not exactly what you want but there's a similarity

3

Sorry, I miss understand your question, you are talking about datatypes, not datasets. My bad.
In that case, what you mean by a python datatype?

4

your example looks like it is just reading one tag and writing the value back to the same tag. here is what I want

myInt01= 42
myInt02 = 2147483699

print pythonToTagDataType(myInt01)
print pythonToTagDataType(myInt02)

the above would print

Int4
Int8
5

Oh, ok now I understand. In your example. Assuming MyInt01&02 comes from any python expression and your data will always be int types, just write (use system.tag.write()) to a tag but this tag should an array type, for example:
image
But you just change it to
image
and inside it changes by itself like:
image

but if you trying to write the string “Int4” to a tag. Just make sure your target tag data type is set to string and code something like:

system.tag.write(‘tagpath’,str(pythonToTagDataType(myInt01))

6

I am not trying to write the datatype to a tag. I want to then use the result to make a tag with that data type using system.tag.configure().

tagSite = {
			"name": "site",
			"valueSource": "memory",
			"dataType": pythonToTagDateType(self.site),
			"value": self.site
		}

system.tag.configure(basePath = "[tagProvider]", tags = [tagSite], collisionPolicy = "m")
7

maybe this is what you mean

num= 42.2
typ=type(num)
numtype = typ(num)
print typ
print numtype
8

Not going to work. Jython uses its “int” datatype for anything that fits in java’s signed 32-bit Integer, and its “long” datatype for any other integers. It uses its 64-bit float for both 32-bit and 64-bit Reals.

9

So what you are saying is i should just use the largest datatype for tags as possible? if the datatype in python is Integer then use Int8 when I create a tag?

1 Like
10

If a python int, use Int4/Integer. If a python long, use Int8/Long, but be aware that python long is really an unlimited bit width type (Java BigInteger) that can lose data in an Int8. Python floats should be placed in Float8/Double.

1 Like
11

You could use a dictionary for easy lookups.

typeDict = {
            'int'  : 'Int4', 
            'long' : 'Int8', 
            'float': 'Float8',
            'str'  : 'String'
           }

type(value).__name__ should give you the type name.

@pturmel, didn’t know that about longs being BigInteger. Learned something new.

1 Like
12

I learned it long ago when some old JDBC drivers blew up on prepUpdates with 64-bit columns. /:

13

This looks like what I might be looking for https://inductiveautomation.com/exchange/132/overview

I may have to modify it to work with lists.