# Consecutive values in a set of rasters

Question asked by tonalca6864 on Oct 22, 2015
Latest reply on Oct 27, 2015 by Dan_Patterson

I'm running ArcGIS 10.2.1 Advanced with SA and Python 2.7

I'm trying to replicate in Python something done in excel: I have a set of 12 rasters with values 0 and 1, each raster representing a month of the year. I need to create an output raster that will count the maximum number of consecutive months occurring. In the excel example above the result is 4 as it starts in December and accumulates through until March. So it is looping through all months.

I have the column called "Rating Count" above sorted. The problem I encounter is with Jan in the "Consec Mo" column as this value is not fixed because it is fed from the December value in the same column.

I have tried this:

```# Set monthly values to 0 and 1

jan = Con(IsNull(Rating_jan), 0, 1)
feb = Con(IsNull(Rating_feb), 0, 1)
mar = Con(IsNull(Rating_mar), 0, 1)
apr = Con(IsNull(Rating_apr), 0, 1)
may = Con(IsNull(Rating_may), 0, 1)
jun = Con(IsNull(Rating_jun), 0, 1)
jul = Con(IsNull(Rating_jul), 0, 1)
aug = Con(IsNull(Rating_aug), 0, 1)
sep = Con(IsNull(Rating_sep), 0, 1)
oct = Con(IsNull(Rating_jan), 0, 1)
nov = Con(IsNull(Rating_jan), 0, 1)
dec = Con(IsNull(Rating_jan), 0, 1)

# Calculate consecutive and MAX value

jan1 = jan
feb2 = Con((feb) == 1, (jan1) + 1, 0)
mar3 = Con((mar) == 1, (feb2) + 1, 0)
apr4 = Con((apr) == 1, (mar3) + 1, 0)
may5 = Con((may) == 1, (apr4) + 1, 0)
jun6 = Con((jun) == 1, (may5) + 1, 0)
jul7 = Con((jul) == 1, (jun6) + 1, 0)
aug8 = Con((aug) == 1, (jul7) + 1, 0)
sep9 = Con((sep) == 1, (aug8) + 1, 0)
oct10 = Con((oct) == 1, (sep9) + 1, 0)
nov11 = Con((nov) == 1, (oct10) + 1, 0)
dec12 = Con((dec) == 1, (nov11) + 1, 0)

Final_Output = CellStatistics([(jan1), (feb2), (mar3), (apr4), (may5), (jun6), (jul7), (aug8), (sep9), (oct10), (nov11), (dec12)]
, "MAXIMUM", "NODATA")

Final_Output.save(OUTWorkspace + "\\" + "Final_Output")
```

But as I said the "jan" value (row 23) is not fixed as in the script so it is not quite what I'm after.

I wonder if someone could give me some hints about how to solve this issue.