topic Re: Model builder, find minimum value, Iterate feature class in ModelBuilder Questions

Model builder, find minimum value, Iterate feature class

jamiefinney — Mon, 04 Aug 2014 13:36:39 GMT

Hi i'm struggling to finalize a model i'm making. from my final results i want to extract the lowest (minimum) value and save it.

i'm using an "iterate feature classes" tool so i need to be able to add %name% into the expression so it will find the lowest value for each of the files that goes into the tool

The column Elev_Diff is the column i want the minimum value from

the name of the file will be a variable (from iterator) called %name%

any ideas?

Re: Model builder, find minimum value, Iterate feature class

RiyasDeen — Mon, 04 Aug 2014 13:59:31 GMT

1. Use summary statistics tool, statistics field will be your Elev_Diff and statistics will be MIN, don't use any case field. This will create a table with one row, containing your minimum Elev_Diff.

2. Then Iterate field value of this table to get your name parameter.

Re: Model builder, find minimum value, Iterate feature class

ChristianWells — Mon, 04 Aug 2014 14:03:31 GMT

Finding the minimum value:

This may be difficult to do as shapefiles don't fully support subqueries (See link here). However, if the data were stored within a Personal Geodatabase (MDB) this could be done using the following query:

Elev_Diff in (select MIN(Elev_Diff) from <featureclass>)

Exporting a file with the name of its input:

I would suggest adding another tool to the end of the model, Copy Features, to copy the selected features to a new file.

Re: Model builder, find minimum value, Iterate feature class

jamiefinney — Mon, 04 Aug 2014 15:26:10 GMT

Thanks for both your suggestions

Christian;

your method looks the more promising of the two. I've converted the data into a geodatabase but i can't seem to get the query to validate. i'm sure its something obvious i'm doing wrong.

[Elev_Diff] in (select MIN([Elev_Diff]) from %name%)

Riyas;

your method would work but would require more processing to create points and bring data back into the tables so i'd be keen to avoid this method if i can.

Re: Model builder, find minimum value, Iterate feature class

ChristianWells — Mon, 04 Aug 2014 16:01:25 GMT

Hi Jamie,

Here is how I set up my model. I put all of the shapefiles into a Personal Geodatabase, then used the iterate tool to loop through them and create a new feature class using the following expression: [Area_SqFt] in (select MIN( [Area_SqFt]) from %Name%)

Re: Model builder, find minimum value, Iterate feature class

jamiefinney — Tue, 05 Aug 2014 08:55:13 GMT

Thanks for your continuing help on this query.

as best as i can see i've got exactly the same query as you but i'm getting an error see attached.

Re: Model builder, find minimum value, Iterate feature class

ChristianWells — Tue, 05 Aug 2014 13:25:55 GMT

No problem. Do you get the error when running the model or verifying the SQL expression? If it happens during the verify, this would be expected because the verification does not substitute the value of the inline variable when evaluating an expression. When the tool runs, the value of the inline variable is substituted in the expression and the results are created based on the substituted values. (See link here)

Re: Model builder, find minimum value, Iterate feature class

jamiefinney — Wed, 06 Aug 2014 13:58:36 GMT

Hi Christian,

Still having trouble getting this to work.

the data is now held in a geodatabase but i'm sill getting errors (see attached) when the model runs

i've used the query using the feature class to feature class tool and select tool in model builder with the same error outcome

Re: Model builder, find minimum value, Iterate feature class

ChristianWells — Wed, 06 Aug 2014 14:04:00 GMT

Can you send a picture of your model and the settings of the "Name” variable?

Re: Model builder, find minimum value, Iterate feature class

jamiefinney — Wed, 06 Aug 2014 14:33:01 GMT

Sure thanks again for your continuing help on this issue

running ArcView 10 (sp5) if that makes any difference

Re: Model builder, find minimum value, Iterate feature class

ChristianWells — Wed, 06 Aug 2014 14:43:20 GMT

I believe that the issues being faces are related to the geodatabase referenced in G (7_Match_DTM_Assessment.gdb) and used for the FC to FC in B. This is currently a File Geodatabase (.gdb) and needs to be a Personal Geodatabase with a .mdb extension.

Re: Model builder, find minimum value, Iterate feature class

jamiefinney — Wed, 06 Aug 2014 15:02:25 GMT

Thats worked at last. i had no idea this query would work in a personal geodatabase rather than a file one.

just curious is there a reason for this or a method that would work for a file geodatabase?

Re: Model builder, find minimum value, Iterate feature class

ChristianWells — Wed, 06 Aug 2014 15:06:45 GMT

I'm glad to hear this worked! The reason that it won't work in a File Geodatabase is because it requires the use of a subquery ("Elev_Diff in (select MIN(Elev_Diff) from <featureclass>”) which isn't supported in a File Geodatabase as of yet. One way that this could be worked around is by running the process through Python and finding the minimum value there instead.