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Wolfram Language

SELECT with variable values

margherita ferrucci

margherita ferrucci, Université Paris Est

Posted 10 years ago

Hi, I have B = {1.3, 1.5, 1.6, 1.6, 1.7}; and geo = {{0.099, 0.199, 0.286, 0.374, 0.452, 0.529}, { 0.598, 0.666, 0.75, 0.833, 0.916, 1.}, { 1.083, 1.166, 1.25, 1.333, 1.4, 1.466}, { 1.533, 1.6, 1.66, 1.73, 1.8, 1.86},{ 1.93, 2., 2.08, 2.166, 2.25, 2.33, 2.41}} I'd like SELECT in geo[[1]] the values < B[[1]], in geo [[2]] the values < B[[2]], in geo [[3]] the values < B[[3]] and so on. So if i use this command Select[#, # <= B[[#]] &] & /@ geo or Select[#, # <= B &] & /@ geo It doesn't run. Someone could help me? Please? Thank you. Margherita

Hi, I have

B = {1.3, 1.5, 1.6, 1.6, 1.7};

and

geo = {{0.099, 0.199, 0.286, 0.374, 0.452, 0.529},
            {  0.598, 0.666, 0.75, 0.833, 0.916, 1.},
            { 1.083, 1.166,   1.25, 1.333, 1.4, 1.466}, 
            { 1.533, 1.6, 1.66, 1.73, 1.8, 1.86},{ 1.93, 2., 2.08, 2.166, 2.25, 2.33, 2.41}}

I'd like SELECT in geo[[1]] the values < B[[1]], in geo [[2]] the values < B[[2]], in geo [[3]] the values < B[[3]] and so on. So if i use this command

Select[#, # <= B[[#]] &] & /@ geo

Select[#, # <= B &] & /@ geo

It doesn't run.

Someone could help me? Please?

Thank you. Margherita

POSTED BY: margherita ferrucci

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Ivan Morozov

Ivan Morozov, Budker Institute of Nuclear Physics

Posted 10 years ago

Hi, Here is a couple of ways to do it: Table[Select[geo[[i]], # < B[[i]] &], {i, 1, Length[geo]}] Inner[Select[#1, Function[x, x < #2]] &, geo, B, List] I.M.

POSTED BY: Ivan Morozov

David Keith

Posted 10 years ago

Hi, Below is example code. The Table function looks at each row and selects the elements of that row < the element row[[n]], where n is the index of the row. Note that it assumes it will always find the element m[[n,n]]. If a row is shorter than it's index number, it will fail to do so and generate an error. It will always work with a matrix with the number of rows <= columns. The Select employs a "pure function." In[3]:= m = Table[RandomInteger[{1, 9}], {i, 5}, {j, 5}]; In[4]:= Table[ Select[m[[i]], # < m[[i, i]] &], {i, Length[m]} ] Out[4]= {{2, 1}, {1}, {3}, {}, {2, 3, 2, 3}} Best, David