Question

I use the following function to perform a conditional operation on a List:

consider[data_, conditionCOL_, conditionVAL_, listOfCol_] :=
  Select[data, (#[[conditionCOL]] == conditionVAL) &][[All, listOfCol]]

Considering the following example :

dalist = Join[Tuples[Range[4], 2]\[Transpose], {Range[16], Range[17, 32, 1]}
         ]\[Transpose];

I use the following to obtain the means of specific columns defined by the function.
This will output the means of entries of column 3 & 4 for which the corresponding entry in column 1 equals 2

Mean@consider[dalist, 1, 2, {3, 4}]

Now, I would like to add constraints/thresholds on the values to be averaged :

Average the values when they are:

• Above minValue (e.g., 3)
• Under maxValue (e.g., 25)

Below, an example is given of values the average value of which should be calculated under the above mentioned constraints.

Answer 1

Since it is not clear whether you want just to exclude the points outside of the limits from the averaging, or to decide whether or not to perform the averaging, I will address both questions. You can use the following functions to postprocess the results of your consider function (they are rather specific, based on your data format):

filter[data : {{_, _} ..}, {min_, max_}] := 
   Select[data, min < #[[1]] < max && min < #[[2]] < max &]

dataWithinLimitsQ[data : {{_, _} ..}, {min_, max_}] := 
   data == filter[data, {min, max}]

meanFiltered[data : {{_, _} ..}, {min_, max_}] := 
   Mean@filter[data, {min, max}]

Here is how you can use them:

In[365]:= dalist=Join[Tuples[Range[4],2]\[Transpose],{Range[16],Range[17,32,1]}]\[Transpose]
Out[365]= {{1,1,1,17},{1,2,2,18},{1,3,3,19},{1,4,4,20},{2,1,5,21},{2,2,6,22},{2,3,7,23},
{2,4,8,24},{3,1,9,25},{3,2,10,26},{3,3,11,27},{3,4,12,28},{4,1,13,29},{4,2,14,30},{4,3,15,31},
{4,4,16,32}}

In[378]:= considered = consider[dalist,1,1,{3,4}]

Out[378]= {{1,17},{2,18},{3,19},{4,20}}

In[379]:= filter[considered,{2,21}]

Out[379]= {{3,19},{4,20}}

In[380]:= dataWithinLimitsQ[considered,{2,21}]

Out[380]= False

In[381]:= meanFiltered[considered,{2,21}]

Out[381]= {7/2,39/2}