topic Re: Arcpy Calculate Field Stores a String in Scientific Notation in Python Questions

Arcpy Calculate Field Stores a String in Scientific Notation

BrandonZaitz — Fri, 07 Dec 2018 19:44:51 GMT

I have an attribute field that is API well numbers and when I calculate a "TEXT" field using arcpy it converts those API numbers into scientific notation. However, when I calculate the field in Arcmap using the GUI it stores the full API number correctly. Has anyone else had this issue? How might i ensure that this doesn't happen?

I have tried both:

arcpy.CalculateField_management(shapefile,fieldname,"!{}!".format(inputfieldname),"PYTHON")

and:

arcpy.CalculateField_management(shapefile,fieldname,"str(!{}!)".format(inputfieldname),"PYTHON")

Re: Arcpy Calculate Field Stores a String in Scientific Notation

JoshuaBixby — Fri, 07 Dec 2018 20:30:21 GMT

Can you give an example number?

Re: Arcpy Calculate Field Stores a String in Scientific Notation

BrandonZaitz — Fri, 07 Dec 2018 21:24:30 GMT

For instance, "30015364700000" will store as "3.00153647e+13".

Re: Arcpy Calculate Field Stores a String in Scientific Notation

DanPatterson_Retired — Fri, 10 Dec 2021 23:36:53 GMT

The field width is > 14 characters and defined as Text for the output field?

The only other thing I can think of is explicitly formatting the output string

a = 30015364700000

"{:<14.0f}".format(a)‍‍‍

Re: Arcpy Calculate Field Stores a String in Scientific Notation

JoshuaBixby — Sat, 08 Dec 2018 16:42:54 GMT

I just tried using your code with both a feature class and shape file, and it works correctly for me, i.e, it doesn't use scientific notation. What version of ArcMap are you using?

Re: Arcpy Calculate Field Stores a String in Scientific Notation

DanPatterson_Retired — Fri, 10 Dec 2021 23:36:56 GMT

If 'Long' in ArcMap or ArcGIS Pro is 32bit integers, then the maximum length of a field and the maximum value is dictated by the integer type. From other c based number types, these are as follows

32bit integers 10 characters with the maximum as 2,147,483,647

Arc* stores long as -2,147,483,648 to 2,147,483,647

64bit integers 19 characters with the maximum as 9,223,372,036,854,775,807

your number is 14 characters long as an integer, 30,015,364,700,000 .... beyond the 32bit long maximum

So if your key has to be that long, then you had better use a text field since

np.iinfo(np.int32).max
2147483647

np.iinfo(np.int64).max
9223372036854775807‍‍‍‍‍‍‍‍‍‍

Now if we convert that integer you have to float32 (32 bit float) we get

np.asarray([30015364700000]).astype(np.float32)
array([3.0015364e+13], dtype=float32)

np.asscalar(a) # not good
30015364268032.0

b =np.asarray([30015364700000]).astype(np.float64)

array([3.00153647e+13])

np.asscalar(b) # better
30015364700000.0

Re: Arcpy Calculate Field Stores a String in Scientific Notation

JoshuaBixby — Sun, 09 Dec 2018 16:31:18 GMT

I had to store the number as double and then use the code to covert to string. As you point out, the number can't be stored in long.

Re: Arcpy Calculate Field Stores a String in Scientific Notation

BrandonZaitz — Mon, 10 Dec 2018 04:28:00 GMT

The field width is 255 and is a string. The code you provided only works if i change the 'f' to 's'.

Re: Arcpy Calculate Field Stores a String in Scientific Notation

BrandonZaitz — Mon, 10 Dec 2018 04:34:19 GMT

Arc Version is 10.6.0.8321

Re: Arcpy Calculate Field Stores a String in Scientific Notation

BrandonZaitz — Mon, 10 Dec 2018 04:34:57 GMT

The field i am calculating from is a Double.

Re: Arcpy Calculate Field Stores a String in Scientific Notation

BrandonZaitz — Fri, 10 Dec 2021 23:36:59 GMT

Below is the entire function:

def CreateAPIText(shapefile,inputfieldname):
     import arcpy
     fieldname = "API_Text"
     #Add field for string API
     arcpy.AddField_management(shapefile,fieldname,"TEXT")
     #Calculate value for API TEXT field
     arcpy.CalculateField_management(shapefile,fieldname,"!{}!".format(inputfieldname),"PYTHON")‍‍‍‍‍‍‍

Re: Arcpy Calculate Field Stores a String in Scientific Notation

JoshuaBixby — Mon, 10 Dec 2018 16:06:01 GMT

I just tested your code using the interactive Python window in ArcCatalog 10.6.1, and the results are as expected for both a feature class table and DBF table:

Re: Arcpy Calculate Field Stores a String in Scientific Notation

BrandonZaitz — Fri, 10 Dec 2021 23:37:01 GMT

Ok, so i have narrowed it down to .format() causing the problem.

The code below DOES NOT give me scientific notation as a result.

def CreateAPIText(shapefile,inputfieldname):
     import arcpy
     fieldname = "API_Text"
     #Add field for string API
     arcpy.AddField_management(shapefile,fieldname,"TEXT",14)
     #Calculate value for API TEXT field
     arcpy.CalculateField_management(shapefile,fieldname,"!API!","PYTHON", "")‍‍‍‍‍‍‍

The code below WAS outputing the fields in scientific notation.

def CreateAPIText(shapefile,inputfieldname):
     import arcpy
     fieldname = "API_Text"
     #Add field for string API
     arcpy.AddField_management(shapefile,fieldname,"TEXT",14)
     #Calculate value for API TEXT field
     arcpy.CalculateField_management(shapefile,fieldname,"!{}!".format(inputfieldname),"PYTHON", "")‍‍‍‍‍‍‍

However, i can not seem to replicate the problem this morning.

If if happens again I may be back but thanks to everyone for the input.

Re: Arcpy Calculate Field Stores a String in Scientific Notation

DanPatterson_Retired — Mon, 10 Dec 2018 20:13:46 GMT

bare formatting can cause some issues depending on what is first passed to it. You can mitigate a bit by specifying how to treat numerics by prespecifying the size and decimals (even for integers)

a = 30015364700000

"{:<16.0f}".format(a)

'30015364700000 '

with a space to spare