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Calculateur de champ pour calculer la différence (valeurs des lignes) dans une seule colonne

youngpark

<\/HEAD>

Bonjour,<\/P>

J'ai une colonne pour l'élévation d'un ensemble de données ponctuelles. Je voudrais créer une nouvelle colonne pour montrer la différence entre les valeurs de la ligne(n) et de la ligne(n+1). Eh bien, je suppose que la façon la plus simple est de calculer dans EXCEL (=abs(A1-A2)) puis de faire une jointure dans ArcGIS. Cependant, je voudrais faire le processus avec "Field calculator". Quelqu'un sait-il comment faire ?<\/P>

Merci d'avance<\/P><\/BODY><\/HTML>

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Accepted answers

DanPatterson_Retired

Added to Table Tools for PRO

as a field calculator sequence function

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youngpark

Thanks, Dan,

I really appreciate it

DanPatterson_Retired

Added to Table Tools for PRO

as a field calculator sequence function

DanPatterson_Retired

Learn GIS ... some python?

Could make this into a script or copy and paste into the python window or your python IDE

<SPAN class="comment token"># ---- </SPAN>
<SPAN class="comment token"># (1) specify the table you want to use, with the OBJECTID field and </SPAN>
<SPAN class="comment token">#&nbsp;&nbsp;&nbsp;&nbsp; the field you want to get sequential differences for</SPAN>
<SPAN class="comment token"># (2) convert the table to a numpy array... there is some magic in that we </SPAN>
<SPAN class="comment token">#&nbsp;&nbsp;&nbsp;&nbsp; 'view' the data as double type (see the vals = line)</SPAN>
<SPAN class="comment token"># (3) perform the difference, diff, by offsetting and slicing the input values)</SPAN>
<SPAN class="comment token"># (4) create an output array to put the values in</SPAN>
<SPAN class="comment token"># (5) 'join' permanently the result (out) to the input using the ExtendTable func</SPAN>
<SPAN class="comment token">#</SPAN>
<SPAN class="comment token"># ---- example below was a quick test to calculate sequential difference in 'Xs'</SPAN>

flds <SPAN class="operator token">=</SPAN> <SPAN class="punctuation token">[</SPAN><SPAN class="string token">'OBJECTID'</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">'Xs'</SPAN><SPAN class="punctuation token">]</SPAN>
pth <SPAN class="operator token">=</SPAN> r<SPAN class="string token">"C:\Your_spaceless_path\Your.gdb\Your_table"</SPAN>
tbl <SPAN class="operator token">=</SPAN> arcpy<SPAN class="punctuation token">.</SPAN>da<SPAN class="punctuation token">.</SPAN>TableToNumPyArray<SPAN class="punctuation token">(</SPAN>pth<SPAN class="punctuation token">,</SPAN> flds<SPAN class="punctuation token">)</SPAN>
vals <SPAN class="operator token">=</SPAN> tbl<SPAN class="punctuation token">[</SPAN><SPAN class="string token">'Xs'</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">.</SPAN>view<SPAN class="punctuation token">(</SPAN>np<SPAN class="punctuation token">.</SPAN>float64<SPAN class="punctuation token">)</SPAN>
<SPAN class="comment token">#</SPAN>
diff <SPAN class="operator token">=</SPAN> vals<SPAN class="punctuation token">[</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">-</SPAN> vals<SPAN class="punctuation token">[</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="operator token">-</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">]</SPAN>&nbsp; <SPAN class="comment token"># ---- changeup the function ----</SPAN>
<SPAN class="comment token">#</SPAN>
out <SPAN class="operator token">=</SPAN> np<SPAN class="punctuation token">.</SPAN>zeros<SPAN class="punctuation token">(</SPAN><SPAN class="punctuation token">(</SPAN>tbl<SPAN class="punctuation token">.</SPAN>shape<SPAN class="punctuation token">[</SPAN><SPAN class="number token">0</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">,</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">,</SPAN> dtype<SPAN class="operator token">=</SPAN><SPAN class="punctuation token">[</SPAN><SPAN class="punctuation token">(</SPAN><SPAN class="string token">'IDs'</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">'<i4'</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="punctuation token">(</SPAN><SPAN class="string token">'Seq_Diff'</SPAN><SPAN class="punctuation token">,</SPAN> <SPAN class="string token">'<f8'</SPAN><SPAN class="punctuation token">)</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">)</SPAN>
out<SPAN class="punctuation token">[</SPAN><SPAN class="string token">'IDs'</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">=</SPAN> tbl<SPAN class="punctuation token">[</SPAN><SPAN class="string token">'OBJECTID'</SPAN><SPAN class="punctuation token">]</SPAN>
out<SPAN class="punctuation token">[</SPAN><SPAN class="string token">'Seq_Diff'</SPAN><SPAN class="punctuation token">]</SPAN><SPAN class="punctuation token">[</SPAN><SPAN class="number token">1</SPAN><SPAN class="punctuation token">:</SPAN><SPAN class="punctuation token">]</SPAN> <SPAN class="operator token">=</SPAN> diff
arcpy<SPAN class="punctuation token">.</SPAN>da<SPAN class="punctuation token">.</SPAN>ExtendTable<SPAN class="punctuation token">(</SPAN>pth<SPAN class="punctuation token">,</SPAN> <SPAN class="string token">'OBJECTID'</SPAN><SPAN class="punctuation token">,</SPAN> out<SPAN class="punctuation token">,</SPAN> <SPAN class="string token">'IDs'</SPAN><SPAN class="punctuation token">)</SPAN>

<SPAN class="comment token"># ---- Seems like overkill? nope... I just stole the code from a pre-existing</SPAN>
<SPAN class="comment token">#&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; snippet, changed the filename, the field of interest and my amazing math function</SPAN><SPAN class="line-numbers-rows"><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN><SPAN>‍</SPAN></SPAN>

Obviously study material, but give it a try sometime.

youngpark

Hi Robert.

Value comparison in a SINGLE column.

NOT comparing field 1 and field 2.

RobertBorchert

abs([field 1] - [field 2])

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