Calculate median values of slices of array associated with histogram bins

4 vues (au cours des 30 derniers jours)
I have an array (array1) which I want to put into histogram bins. I have a second array (array2) which is the same length.
I can sum the values of array2 in each bin with this:
[count, edges, idx] = histcounts(array1,edges);
binsums = accumarray(idx,array2);
But how can I calculate the median values of array2 in each bin?

Réponse acceptée

Star Strider
Star Strider le 15 Nov 2023
I would use another accumarray call:
binmedians = accumarray(idx+1, (1:numel(idx)).', [], @(x)median(array2(x)))
Creating data and correcting for ‘idx’ having 0 for some elements (making them inappropriate index values) —
array1 = randn(1E+3,1);
array2 = randn(1E+3,1);
edges = 1:9;
[count, edges, idx] = histcounts(array1,edges);
binsums = accumarray(idx+1,array2)
binsums = 4×1
-13.0331 20.8357 -1.5279 -2.0722
binmedians = accumarray(idx+1, (1:numel(idx)).', [], @(x)median(array2(x)))
binmedians = 4×1
-0.0237 0.2213 0.1113 -1.0361
.
  2 commentaires
dormant
dormant le 15 Nov 2023
Thank you very much. Some of the values going into the median ar NaNs, but I can handle them.
Star Strider
Star Strider le 15 Nov 2023
As always, my pleasure!
Use the missingflag option that works best for you.
One such:
binmedians = accumarray(idx+1, (1:numel(idx)).', [], @(x)median(array2(x),'omitmissing'))
There are several others.
.

Connectez-vous pour commenter.

Plus de réponses (1)

Steven Lord
Steven Lord le 15 Nov 2023
I would use the groupsummary function with the grouping information from the idx variable.
If all you want is the bin numbers, you could also use the discretize function instead of histcounts.
  1 commentaire
dormant
dormant le 15 Nov 2023
Thanks you very much. I'll try this as well as the solution suggested by Star Strider.

Connectez-vous pour commenter.

Produits


Version

R2023b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by