topic Re: Attribute Table- Field calculation using conditional IF in Geoprocessing Questions

Attribute Table- Field calculation using conditional IF

BabakMirshahi — Wed, 04 Jan 2012 13:09:26 GMT

Hi,

To calculate the values in Field: "Start_time" using those in Field: "Period_Sta", I tried expression below. However it doesn't work. Can anybody help to debug it?
Thanks

If [Period_Sta] =="01/01" Then
[Start_time]= ???1???
elseif [Period_Sta] == "01/04" Then
[Start_time]= ???91???
elseif [Period_Sta] == "30/09" Then
[Start_time]= ???273???
elseif [Period_Sta] == "31/12" Then
[Start_time]= ???365???
end if

Re: Attribute Table- Field calculation using conditional IF

BruceNielsen — Wed, 04 Jan 2012 14:13:08 GMT

If [Start_time] is defined as a numeric field, then you don't need the quotes around the value ([Start_time] = 1).

Re: Attribute Table- Field calculation using conditional IF

BabakMirshahi — Thu, 05 Jan 2012 07:25:09 GMT

[Period_Sta] is a string field & [Start_time] is defined as Double. Even after removing the "", it sends the same error message: "There was a failure during processing".

Re: Attribute Table- Field calculation using conditional IF

BabakMirshahi — Thu, 05 Jan 2012 11:26:55 GMT

If [Start_time] is defined as a numeric field, then you don't need the quotes around the value ([Start_time] = 1).

[Period_Sta] is a string field & [Start_time] is defined as Double. Even after removing the "", it sends the same error message: "There was a failure during processing".

Re: Attribute Table- Field calculation using conditional IF

ChrisSnyder — Sun, 12 Dec 2021 05:43:30 GMT

An update cursor in Python would be much easier to format this, but if you wanted to do it in the field calculator, the Python formatted code would look like this ugly thing here:

gp.CalculateField_management(myFC, "Start_time", "returnvalue(!Period_Sta!)", "PYTHON", "def returnvalue(periodStaFieldValue):\\n if periodStaFieldValue == '01/01':\\n   return '1'\\n elif periodStaFieldValue == "01/04":\\n   return '91'\\n elif periodStaFieldValue == "30/09":\\n   return '273'   \\n elif periodStaFieldValue == "31/12":\\n   return '365'")

or in an update cursor...

updateRows = arcpy.UpdateCursor(myFC)
for updateRow in updateRows:
   if updateRow.Period_Sta ==  '01/01':
      updateRow.Start_time = '1'
   elif updateRow.Period_Sta ==  '01/04':
      updateRow.Start_time = '91'
   elif updateRow.Period_Sta ==  '30/09':
      updateRow.Start_time = '273'
   elif updateRow.Period_Sta ==  '31/12':
      updateRow.Start_time = '365'
   updateRows.updateRow(updateRow)
del updateRow, updateRows

Re: Attribute Table- Field calculation using conditional IF

RichardFairhurst — Thu, 05 Jan 2012 19:29:55 GMT

Hi,

To calculate the values in Field: "Start_time" using those in Field: "Period_Sta", I tried expression below. However it doesn't work. Can anybody help to debug it?
Thanks

If [Period_Sta] =="01/01" Then
[Start_time]= �??1�?�
elseif [Period_Sta] == "01/04" Then
[Start_time]= �??91�?�
elseif [Period_Sta] == "30/09" Then
[Start_time]= �??273�?�
elseif [Period_Sta] == "31/12" Then
[Start_time]= �??365�?�
end if

Try adding an unqualified Else condition at the end that calculates [Start_time] = [Start_time] if none of the other conditions are met. Also, if [Period_Sta] has Null values you either need to select non-Null values first or else make the first condition If IsNull([Period_Sta]) Then [Start_time] = [Start_time]