Fit a distribution line in a histogram - Help!

Hi all,

This is my code and the result i got. Somthing is not right, i used histfit(cntH,NumBins,'kernel'), i was expecting the distribution line is starting from zero and fit into the bars......How can i fix that?

clear all
clc

% yG = total 
load yH

% specify number of bins and edges of those bins; this example evenly spaces bins
NumBins = 100;
BinEdges = linspace(0,35,70);
% use histcounts and specify your bins
cntH = histcounts(yH,'BinEdges',BinEdges);
% plot
figure(1); cla; hold on;
% convert bin edges into bin centers
b = BinEdges(1:end-1)+diff(BinEdges)/2
% use bar
bar(b,[cntH'],'stacked')
histfit(cntH,NumBins,'kernel');
% Labels   
xlabel('Length of single walled carbon nanotubes (mm)')
ylabel('Count of CNT(log scale)')
set(gca,'YScale','log')
title('Count of CNT against length of SWCNTs in 0 degree(log scale)')

[J. Alex Lee]

don't look at your plot in log-y...also, 'kernel' may not behave well with your data.

try log-normal distribution.

[ka chun yick]

I tried the log-normal function, it seems no line appear in the graph.....

clear all
clc

% yG = total 
load yH

% specify number of bins and edges of those bins; this example evenly spaces bins
NumBins = 100;
BinEdges = linspace(0,35,70);
% use histcounts and specify your bins
cntH = histcounts(yH,'BinEdges',BinEdges);
% plot
figure(1); cla; hold on;
% convert bin edges into bin centers
b = BinEdges(1:end-1)+diff(BinEdges)/2
% use bar
bar(b,[cntH'],'stacked')
pd_normal = fitdist(yH,'Normal')
% Labels   
xlabel('Length(mm)')
ylabel('Count(log scale)')
set(gca,'YScale','log')
title('Count in 0 degree(log scale)')

[J. Alex Lee]

what is the value of pd_normal?

perhaps you can share the actual data.

also, what exactly is your objective/problem?

[ka chun yick]

The load yH is from the imported excel data (xls file). I wanted to plot a distribution line along the histogram.

[J. Alex Lee]

You need to be more specific. Presumably you want to do something with the parameters of the underlying fitted distribution.

If you just want to draw a line, you can get the bin edges and counts from the histcounts function, find the bin centers, and use the plot command on that pair.

plot(b,cntH','-')

[ka chun yick]

Thanks. This is what i wanted. But i got a question: how to smooth the line?