Set colors for specific entries of heat map

Hi all,

I have constructed an heatmap based on a diagonal 50x50 matrix (that I attached to the csv file below).

My code looks as follows:

T1 = readtable('/Users/federiconutarelli/Desktop/Second_work/pivot_own.csv');
T1 = removevars(T1, 'Var1');
T1(1,:) = [];
T1_mat = T1{:,:};
T1_mat(T1_mat==0) = NaN;
ax = gca;
xvalues = {'ACETYLCYSTEINE' 'ACETYLSALICYLIC ACID' 'ACICLOVIR' 'ALPRAZOLAM' 'AMLODIPINE' 'AMOXICILLIN' 'BETAMETHASONE' 'BISOPROLOL' 'BUDESONIDE' 'CARBAMAZEPINE' 'CARBIDOPA + LEVODOPA' 'CETIRIZINE' 'CICLOSPORIN' 'CLINDAMYCIN' 'CLOBETASOL' 'DESMOPRESSIN' 'DICLOFENAC' 'EPINEPHRINE' 'ESTRADIOL' 'FINASTERIDE' 'FLUCONAZOLE' 'FLUOXETINE' 'FUROSEMIDE' 'GOSERELIN' 'HYDROCORTISONE' 'IBUPROFEN' 'INSULIN HUMAN ISOPHANE' 'IRON FERROUS' 'LACTULOSE' 'LEVOTHYROXINE SODIUM' 'LOPERAMIDE' 'MAGNESIUM' 'MESALAZINE' 'METHYLPREDNISOLONE' 'METOPROLOL' 'METRONIDAZOLE' 'NICOTINE' 'OCTREOTIDE' 'OMEPRAZOLE' 'ONDANSETRON' 'PARACETAMOL' 'POTASSIUM' 'RISPERIDONE' 'SALBUTAMOL' 'SPIRONOLACTONE' 'SULFASALAZINE' 'TESTOSTERONE' 'TOBRAMYCIN' 'TRIPTORELIN' 'VALPROIC ACID'};
yvalues = {'ACETYLCYSTEINE' 'ACETYLSALICYLIC ACID' 'ACICLOVIR' 'ALPRAZOLAM' 'AMLODIPINE' 'AMOXICILLIN' 'BETAMETHASONE' 'BISOPROLOL' 'BUDESONIDE' 'CARBAMAZEPINE' 'CARBIDOPA + LEVODOPA' 'CETIRIZINE' 'CICLOSPORIN' 'CLINDAMYCIN' 'CLOBETASOL' 'DESMOPRESSIN' 'DICLOFENAC' 'EPINEPHRINE' 'ESTRADIOL' 'FINASTERIDE' 'FLUCONAZOLE' 'FLUOXETINE' 'FUROSEMIDE' 'GOSERELIN' 'HYDROCORTISONE' 'IBUPROFEN' 'INSULIN HUMAN ISOPHANE' 'IRON FERROUS' 'LACTULOSE' 'LEVOTHYROXINE SODIUM' 'LOPERAMIDE' 'MAGNESIUM' 'MESALAZINE' 'METHYLPREDNISOLONE' 'METOPROLOL' 'METRONIDAZOLE' 'NICOTINE' 'OCTREOTIDE' 'OMEPRAZOLE' 'ONDANSETRON' 'PARACETAMOL' 'POTASSIUM' 'RISPERIDONE' 'SALBUTAMOL' 'SPIRONOLACTONE' 'SULFASALAZINE' 'TESTOSTERONE' 'TOBRAMYCIN' 'TRIPTORELIN' 'VALPROIC ACID'};
h = heatmap(xvalues,yvalues,T1_mat);

h.Title = 'Own Elasticities';
h.XLabel = 'Molecules';
h.YLabel = 'Molecules';
%colormap(flipud(hot))

Now what I would like to do is to color some of the entries on the main diagonal according to shades of red and make a separate legend with a writing "Significant entries colored according to shades of red"

Is it possible to do so?

Thank you,

Federico

Answer 1

[Salman Ahmed]

Hi,

From my understanding you wish to highlight specific cells in a heatmap but this is not a feature present currently with heatmap. Some of the workarounds that you can proceed with are:

1. Use imagesc to achieve a similar map. Refer link for more details.
2. Use a custom colormap. You can mark the cells to be highlighted at the extreme limit and assign a different color in the your custom map. Note, you can create one using colormapeditor. Have a look at a sample modified code, where I have highlighted the (1,1) cell:

T1 = readtable('pivot_own.csv');
T1 = removevars(T1, 'Var1');
T1(1,:) = [];
T1_mat = T1{:,:};
T1_mat(T1_mat==0) = NaN;
T1_mat(1,1) = -1.5; % Marking cell at extreme
ax = gca;
xvalues = {'ACETYLCYSTEINE' 'ACETYLSALICYLIC ACID' 'ACICLOVIR' 'ALPRAZOLAM' 'AMLODIPINE' 'AMOXICILLIN' 'BETAMETHASONE' 'BISOPROLOL' 'BUDESONIDE' 'CARBAMAZEPINE' 'CARBIDOPA + LEVODOPA' 'CETIRIZINE' 'CICLOSPORIN' 'CLINDAMYCIN' 'CLOBETASOL' 'DESMOPRESSIN' 'DICLOFENAC' 'EPINEPHRINE' 'ESTRADIOL' 'FINASTERIDE' 'FLUCONAZOLE' 'FLUOXETINE' 'FUROSEMIDE' 'GOSERELIN' 'HYDROCORTISONE' 'IBUPROFEN' 'INSULIN HUMAN ISOPHANE' 'IRON FERROUS' 'LACTULOSE' 'LEVOTHYROXINE SODIUM' 'LOPERAMIDE' 'MAGNESIUM' 'MESALAZINE' 'METHYLPREDNISOLONE' 'METOPROLOL' 'METRONIDAZOLE' 'NICOTINE' 'OCTREOTIDE' 'OMEPRAZOLE' 'ONDANSETRON' 'PARACETAMOL' 'POTASSIUM' 'RISPERIDONE' 'SALBUTAMOL' 'SPIRONOLACTONE' 'SULFASALAZINE' 'TESTOSTERONE' 'TOBRAMYCIN' 'TRIPTORELIN' 'VALPROIC ACID'};
yvalues = {'ACETYLCYSTEINE' 'ACETYLSALICYLIC ACID' 'ACICLOVIR' 'ALPRAZOLAM' 'AMLODIPINE' 'AMOXICILLIN' 'BETAMETHASONE' 'BISOPROLOL' 'BUDESONIDE' 'CARBAMAZEPINE' 'CARBIDOPA + LEVODOPA' 'CETIRIZINE' 'CICLOSPORIN' 'CLINDAMYCIN' 'CLOBETASOL' 'DESMOPRESSIN' 'DICLOFENAC' 'EPINEPHRINE' 'ESTRADIOL' 'FINASTERIDE' 'FLUCONAZOLE' 'FLUOXETINE' 'FUROSEMIDE' 'GOSERELIN' 'HYDROCORTISONE' 'IBUPROFEN' 'INSULIN HUMAN ISOPHANE' 'IRON FERROUS' 'LACTULOSE' 'LEVOTHYROXINE SODIUM' 'LOPERAMIDE' 'MAGNESIUM' 'MESALAZINE' 'METHYLPREDNISOLONE' 'METOPROLOL' 'METRONIDAZOLE' 'NICOTINE' 'OCTREOTIDE' 'OMEPRAZOLE' 'ONDANSETRON' 'PARACETAMOL' 'POTASSIUM' 'RISPERIDONE' 'SALBUTAMOL' 'SPIRONOLACTONE' 'SULFASALAZINE' 'TESTOSTERONE' 'TOBRAMYCIN' 'TRIPTORELIN' 'VALPROIC ACID'};
h = heatmap(xvalues,yvalues,T1_mat);
h.Colormap = CustomColormap; % Add your custom map here. 
h.Title = 'Own Elasticities';
h.XLabel = 'Molecules';
h.YLabel = 'Molecules';

Note you can add text to indicate the extreme value indicates highlighted. Hope it helps.