expressão python

Question

<\/HEAD>Olá a todos,<\/P> <\/P> na imagem você pode ver uma tabela de atributos de um medidor de calor. O número do medidor de calor é 11250423. O status do calor é fornecido mensalmente. Agora eu quero fazer uma expressão para obter o consumo de cada mês.<\/P> <\/P> <\/P> <\/P> <\/P> na teoria eu tenho que fazer algo assim:<\/P> y_(i+1)-y_(i) = consumo<\/P> <\/P> Mês 1 (janeiro): y_(1+1)-y_(1) = consumo de Janeiro<\/P> Mês 2 (fev): y_(2+1)-y_(2) = consumo de Fevereiro<\/P> ...<\/P> Mês 12 (dez): y_(12+1)-y_(12) = consumo de Dezembro<\/P> <\/P> alguém sabe como escrever uma expressão no arcgis? Eu quero criar um novo campo para calcular.<\/P> <\/P> Obrigado pela ajuda.<\/P> <\/P> Saudações da Alemanha!<\/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?