i need to find the x,y points and plot those points finding the slope making a line in x,y plane. How can i get it automatically

finding the slope and plotting it in graph

Walter Roberson 2019-4-20

Is your input the png file itself, and you have to figure out the coordinates of the blue line??

sisir regmi 2019-4-21

yes its a png file and i need to figure out the coordinated of the lines also i need to find the slope from the coordinates and plot it. Thank you

x=[0.06,.155,.180,.25,.28,.418,.554,1.737,1.822,1.823,1.824,2.029,2.062,2.073,2.075,2.091,2.108,2.11,2.157,3.12,3.26,3.37,3.44,3.54,3.56,3.58,3.92,4.08,4.17,4.19,4.36,4.38,4.39,4.45,4.456,4.44,4.46,4.35,4.55,4.69,5.138,5.28,5.40,5.54,5.67,5.78,5.80,5.81,5.900,5.9001,5.91,5.92,6.19,6.20,6.21,6.423,6.57,6.65,6.71,6.72,6.83,6.85,6.92,7.11,7.25]

y=[13.22,179.6,438.2,687.8,981.3,1152,931,91.24,80.37,37.61,12.09,70.55,96.34,125.6,73.59,57.15,88.75,80.1,111.6,258.1,40.66,42.7,60.61,236.8,239.8,212.1,128.4,46.09,40.58,47.62,90.86,174.5,244.2,316.9,482,614.4,775.3,923.3,782.3,486.9,75.65,35.83,31.34,35.01,28.84,36.18,31.63,16.6,11.6,4.97,11.38,10.54,9.34,13.16,21.86,28.17,73.86,148.5,469.1,763.6,914.6,301.9,192,118.5,79.65,49.06]

x=x';

y=y';

i have taken the points manually now want to find the slope of the points

Walter Roberson 2019-4-21

Look in the File Exchange for tag digitize

gradient() for slopes

sisir regmi 2019-4-21

can we read the x,y coordinates automatically from the avobe figure?

Walter Roberson 2019-4-21

There are over 20 File Exchange contributions that do their best to return the line coordinates https://www.mathworks.com/matlabcentral/fileexchange?q=tag%3Adigitize

Your image might be too dense for it to work properly: you effectively have multiple y for each x because of low resolution.

David Wilson 2019-4-21

Are you sure you want the gradient of your data?

I should also comment that from your above (frequency?) plot, it does seem very noisy, and given that extracting the gradient operation tends to amplify the high frequency components, (especially if you do something crude like finite differences), then your resultant plot of the derivative will be very niosy.

If I was to smooth your data, I'd think very carefully about how to do it. I'd probably fit a smoothing spline through the data, and then differentiate that. But plotted over the range you have shown above, it's likely to be a considerable mess.

finding the slope and plotting it in graph

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