python-expressie

GregorMitzlaff

<\/HEAD>

Hallo allemaal,<\/P>

<\/P>

op de afbeelding zie je een attributentabel van een warmte meter. Het nummer van de warmte meter is 11250423. De warmte status wordt maandelijks gegeven. Nu wil ik een expressie maken om het verbruik van elke maand te krijgen.<\/P>

<\/P>

<\/P>

<\/P>

<\/P>

in theorie moet ik zoiets doen:<\/P>

y_(i+1)-y_(i) = verbruik<\/P>

<\/P>

Maand 1 (januari): y_(1+1)-y_(1) = verbruik van januari<\/P>

Maand 2 (feb): y_(2+1)-y_(2) = verbruik van februari<\/P>

...<\/P>

Maand 12 (dec): y_(12+1)-y_(12) = verbruik van december<\/P>

<\/P>

weet iemand hoe je een expressie schrijft in arcgis? Ik wil een nieuw veld maken om te berekenen.<\/P>

<\/P>

Bedankt voor de hulp.<\/P>

<\/P>

Groeten uit Duitsland!<\/P><\/BODY><\/HTML>

Arne_Gelfert

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:

<SPAN class="keyword token">SELECT</SPAN> month<SPAN class="punctuation token">(</SPAN>Datum<SPAN class="punctuation token">)</SPAN> <SPAN class="keyword token">AS</SPAN> <SPAN class="punctuation token">[</SPAN>MONTH<SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">,</SPAN> year<SPAN class="punctuation token">(</SPAN>Datum<SPAN class="punctuation token">)</SPAN> <SPAN class="keyword token">AS</SPAN> <SPAN class="punctuation token">[</SPAN>YEAR<SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="token function">SUM</SPAN><SPAN class="punctuation token">(</SPAN>Wärmemenge<SPAN class="punctuation token">)</SPAN> <SPAN class="keyword token">AS</SPAN> TOTAL
<SPAN class="keyword token">FROM</SPAN> <SPAN class="operator token"><</SPAN>YOUR <SPAN class="keyword token">DATA</SPAN> SOURCE<SPAN class="operator token">></SPAN>
<SPAN class="keyword token">GROUP</SPAN> <SPAN class="keyword token">BY</SPAN> month<SPAN class="punctuation token">(</SPAN>Datum<SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">,</SPAN> year<SPAN class="punctuation token">(</SPAN>Datum<SPAN class="punctuation token">)</SPAN>
<SPAN class="comment token">-- ORDER BY [MONTH], [YEAR]</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

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