Internally, WEAP uses a value of -9999 to represent missing values when reading from a file, and does not include them on charts or tables.  Note: many WEAP calculations will not accept MissingValue and will cause an error.  For example, if your climate data has gaps, you must fill these gaps in order to use the data for catchment calculations.  The gaps can be filled by one of the ReadFromFile methods above (Interpolate, Repeat, Replace), or you can edit the file yourself to fill the gaps.  One exception is the comparison of streamflow gauge data to calculated streamflow -- in this case, missing values are fine, although no comparison will be made for any timestep for which the gauge data is missing.  If you are aggregating daily values from a CSV file to weekly or monthly values (using ReadFromFile's Sum or Average), any weeks or months that have any missing daily values will be equal to MissingValue.  By default, most variables, including user-defined variables, do not allow a value of MissingValue.  To change this (user-defined variables only), see Customizing Data Variables.

Any expression that includes a MissingValue (-9999) will be equal to MissingValue, e.g.,  MissingValue / 12 will be MissingValue.  

This could happen if you are reading values from a file, such as river gauge values, and some are missing.  If you were converting them from CFS to CMS by dividing by 35.315, previously WEAP would have incorrectly divided any MissingValues (-9999) by 35.315, yielding -283.14.  Also, for any operation that totals or averages a group of numbers that includes at least one MissingValue, the result will be the MissingValue.  For example, if you are aggregating daily streamflow values to be monthly, if even one of the daily values is missing, the aggregated value for that month will be missing.  Remember, the ReadFromFile function can fill in missing values using several different functions (Interpolate, Repeat, Replace).

Any value of -9999 will not show on charts or tables; there will be a gap at that place.


If( ReadFromFile(Climate.csv, , , , , Mark) = MissingValue, \Key\Default Wind Speed,  ReadFromFile(Climate.csv, , , , , Mark) )       

If the value for a timestep in Climate.csv is missing, use instead the value from the key assumption \Key\Default Wind Speed.