Skip to main content

Is there a way to do conditional matrix loop using 'continue'


enter image description hereI have the following:


n = 3;
m = 5;
ww = RandomReal[{0, 0.1}, {n, n}];
uu = RandomReal[{0, 1}, {m, n}];
pp = RandomReal[{0, 1}, {n, n}];
ss = RandomInteger[{0, 5}, {m, n}];
Grid[{{"ww", "uu", "pp", "ss"}, {ww // TableForm, uu // TableForm, 

   pp // TableForm, ss // TableForm}}, Spacings -> {5, 2}, 
 Dividers -> All]

where I would like to look at every element of matrix ss and produce a matrix tt, with zeroes at the locations in ss which have zeroes, and in all other positions do the following:


tt = (-1/Subscript[ww, m]) Log[(1 - uu)/(Subscript[pp, m - 1])],

where Subscript[ww, m] is the value at index of ww matrix and where Subscript[pp, m - 1] is the value at index-1 of pp matrix.


So for example if the first value ever read from matrix ss happens to be 2, then value taken from matrix ww would be from the row 2, but from pp would be from row 1.


Also how to tell difference between a 0 as a valid value from within the matrix elements to end of matrix if I do not know the actual size of the matrix beforehand?


Given the data as above, tt matrix would be like this: enter image description here




Answer



Two gaps in the information provided in the question : First, the elements of ss cannot be greater than 3 (row dimension of ww and pp). Second, how do you process the case ss[[i, j]] = 1 ? (Which row of pp do you use?) You need to change the rule so that either ss does not contain any 1s or treat the 1s as you treat 0s. In the following I restricted ss to values in {0, 2, 3}.


n = 3; m = 5;
ww = RandomReal[{0, 0.1}, {n, n}];
uu = RandomReal[{0, 1}, {m, n}];
pp = RandomReal[{0, 1}, {n, n}];
ss = RandomChoice[{0, 2, 3}, {m, n}];

Define tt as


tt = SparseArray[{i_, j_} /; ss[[i, j]] != 0 :>

   (-1/ww[[ss[[i, j]], j]]) Log[(1 - uu[[i, j]])/ pp[[ss[[i, j]] - 1, j]]], {m, n}]

With this,


Grid[Transpose@{{"ww", "uu", "pp", "ss", "tt"}, 
  TableForm /@ {ww, uu, pp, ss, Normal[tt]}}, Spacings -> {5, 2}, Dividers -> All]

enter image description here


UPDATE: Incorporating OP's latest clarifications:


ww2 = Prepend[ww, {a, b, c}];
f2[i_, j_] := (-1/ww2[[ss[[i, j]] + 1, j]]) Log[(1 - uu[[i, j]])/pp[[ss[[i, j]], j]]];

tt2 = SparseArray[{i_, j_} /; ss[[i, j]] != 0 :> f2[i, j], {m, n}];
Grid[Transpose@{{"uu", "ww", "pp", "ss", "ww2", "tt2"}, 
    TableForm /@ {uu, ww, pp, ss, ww2, Normal[tt2]}},
 Spacings -> {5, 2}, 
 Dividers -> {{All, {1 -> Thick, -1 -> Thick}}, 
              {All, {5 -> Thick, 1 -> Thick, -1 -> Thick}}}]

enter image description here


Comments

Post a Comment

Popular posts from this blog

plotting - Filling between two spheres in SphericalPlot3D

Manipulate[ SphericalPlot3D[{1, 2 - n}, {θ, 0, Pi}, {ϕ, 0, 1.5 Pi}, Mesh -> None, PlotPoints -> 15, PlotRange -> {-2.2, 2.2}], {n, 0, 1}] I cant' seem to be able to make a filling between two spheres. I've already tried the obvious Filling -> {1 -> {2}} but Mathematica doesn't seem to like that option. Is there any easy way around this or ... Answer There is no built-in filling in SphericalPlot3D . One option is to use ParametricPlot3D to draw the surfaces between the two shells: Manipulate[ Show[SphericalPlot3D[{1, 2 - n}, {θ, 0, Pi}, {ϕ, 0, 1.5 Pi}, PlotPoints -> 15, PlotRange -> {-2.2, 2.2}], ParametricPlot3D[{ r {Sin[t] Cos[1.5 Pi], Sin[t] Sin[1.5 Pi], Cos[t]}, r {Sin[t] Cos[0 Pi], Sin[t] Sin[0 Pi], Cos[t]}}, {r, 1, 2 - n}, {t, 0, Pi}, PlotStyle -> Yellow, Mesh -> {2, 15}]], {n, 0, 1}]
Post a Comment
Read more

plotting - Plot 4D data with color as 4th dimension

I have a list of 4D data (x position, y position, amplitude, wavelength). I want to plot x, y, and amplitude on a 3D plot and have the color of the points correspond to the wavelength. I have seen many examples using functions to define color but my wavelength cannot be expressed by an analytic function. Is there a simple way to do this? Answer Here a another possible way to visualize 4D data: data = Flatten[Table[{x, y, x^2 + y^2, Sin[x - y]}, {x, -Pi, Pi,Pi/10}, {y,-Pi,Pi, Pi/10}], 1]; You can use the function Point along with VertexColors . Now the points are places using the first three elements and the color is determined by the fourth. In this case I used Hue, but you can use whatever you prefer. Graphics3D[ Point[data[[All, 1 ;; 3]], VertexColors -> Hue /@ data[[All, 4]]], Axes -> True, BoxRatios -> {1, 1, 1/GoldenRatio}]
Post a Comment
Read more

plotting - Mathematica: 3D plot based on combined 2D graphs

I have several sigmoidal fits to 3 different datasets, with mean fit predictions plus the 95% confidence limits (not symmetrical around the mean) and the actual data. I would now like to show these different 2D plots projected in 3D as in but then using proper perspective. In the link here they give some solutions to combine the plots using isometric perspective, but I would like to use proper 3 point perspective. Any thoughts? Also any way to show the mean points per time point for each series plus or minus the standard error on the mean would be cool too, either using points+vertical bars, or using spheres plus tubes. Below are some test data and the fit function I am using. Note that I am working on a logit(proportion) scale and that the final vertical scale is Log10(percentage). (* some test data *) data = Table[Null, {i, 4}]; data[[1]] = {{1, -5.8}, {2, -5.4}, {3, -0.8}, {4, -0.2}, {5, 4.6}, {1, -6.4}, {2, -5.6}, {3, -0.7}, {4, 0.04}, {5, 1.0}, {1, -6.8}, {2, -4.7}, {3, -1.
Post a Comment
Read more