Creating sum layers by summing field values from *.dbf files using ArcPy?

Question

I have 490 consecutive daily rainfall shapefiles/.dbf files in a single directory. Each consists of a uniform even-spaced grid of 220 points having uniform pointIDs, number of records, field names and datatypes, and a field containing a daily recorded rainfall value (in inches) for each point/record.

I'm trying to read in the first 7 .dbf's from a list, read their rainfall values, sum them up for each record/point, create a new shapefile (ie. weeksum1.shp) having the same table structure as the daily files and containing weekly calculated sums for each record. Repeat for the next 7 .dbf's until 70 weeks (490/7) of data are created.

I've successfully done this by converting the shapefile's to raster, but I have to keep associated attributes for each point which I didn't foresee before spending a lot of time building scripts/models to work with rasters...

I am using ArcGIS 10 (ArcInfo) SP4 with all extensions, ArcPy, Excel 2007

Answer 1

You could try merging 7 DBFs, summarize based on the pointid, then joining the resulting table back to one of the point shapefiles.

@nmpeterson:

The specific tools are Merge (obviously) and then Summary Statistics, with pointid as the Case field and rainfall as a Statistic field, using the SUM option.