expresión python

Question

<\/HEAD>Hola a todos,<\/P> <\/P> en la imagen pueden ver una tabla de atributos de un heat meter. El número del heat meter es 11250423. El estado del heat se da mensualmente. Ahora quiero hacer una expresión para obtener el consumo de cada mes.<\/P> <\/P> <\/P> <\/P> <\/P> en teoría tengo que hacer algo así:<\/P> y_(i+1)-y_(i) = consumo<\/P> <\/P> Mes 1 (enero): y_(1+1)-y_(1) = consumo de enero<\/P> Mes 2 (feb): y_(2+1)-y_(2) = consumo de febrero<\/P> ...<\/P> Mes 12 (dic): y_(12+1)-y_(12) = consumo de diciembre<\/P> <\/P> ¿alguien sabe cómo escribir una expresión en arcgis? Quiero crear un nuevo campo para calcular.<\/P> <\/P> Gracias por ayudar.<\/P> <\/P> ¡Saludos desde Alemania!<\/P><\/BODY><\/HTML>

Arne_Gelfert · Answer

Gregor, I'm sure what you're trying to accomplish can be done in field calculator. In my experience, the more massaging I have to do with data, the more I want to do it near the source. Usually that's fastest and I find it more transparent. Don't know where you're getting your data. But this would be easy to do in SQL: SELECT month(Datum) AS [MONTH], year(Datum) AS [YEAR], SUM(Wärmemenge) AS TOTAL FROM <YOUR DATA SOURCE> GROUP BY month(Datum), year(Datum) -- ORDER BY [MONTH], [YEAR]‍‍‍‍ So admittedly, this may not work in in your situation but if it does and you can create a query layer or database view, I bet it would perform better. Schöne Grüße

DavidPike · Answer

Id say order it descending then have a codeblock that gets the value for the row in WAERMEMENGE, stores it then does the calculation in the next row. I've not tested the below, and its been ages since ive done this so it's very likely horrifically wrong, but it may give you an idea.

##pre-logic:

def calculate_stuff(field):

global previous_value

result = field - previous value

previous_value = field

return result

##code window:

calculate_stuff(!WAERMEMENGE!)

bixb0012 · Answer

What application/environment are you working in?  Is the screenshot an ArcGIS Pro table?