Basic 2D-contour plot

Hello everyone,

I am very new to Matlab and want to use it for a very basic data visualisation. I found some examples about 2D-contour plots, but no example worked for me and sometimes I had difficulties understanding certain functions.

I have a data file, which contains coordinates in x- and y-direction (first row and first column of an excel sheet). For every given position of these x- and y-coordinates there is a value.

There are plots that look very similar to what I aim for in the end:

My problem is, that getting the data out of my excel-file seems complicated and I don't know how to assign the coordinates to the values in Matlab.

I have currently a visualisation, but this one is based on Excel and does not fit certain optical requirements:

Also the interpolation of data between measured values is not very well done.

I am very glad about every answer that helps!

Best regards

Moritz

Answer 1

[Star Strider]

One optiono is to use the first column and first row as the appropriate coordinate vectors, and then the rest of the matrix as the array to use with contourf.

I am not certain what result you want.

One possibility —

Data = readmatrix('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1084750/data.xlsx')

Data = 11×53

NaN 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 0 153 158 434 372 336 322 241 266 227 213 229 237 248 241 213 236 219 222 258 236 216 282 346 390 349 288 286 352 306 1 131 258 452 417 386 349 368 286 245 221 252 213 224 227 210 248 196 234 256 243 248 336 345 221 325 322 336 322 342 2 137 438 413 425 409 382 346 264 239 224 215 219 203 222 258 214 221 229 229 316 214 279 244 237 319 339 314 390 222 3 139 141 382 417 375 352 311 343 258 262 213 214 210 209 215 217 227 195 264 275 250 243 286 313 306 279 336 286 288 4 132 134 471 425 385 379 351 325 252 250 227 219 219 224 221 245 264 212 196 286 229 271 365 342 266 271 316 314 282 5 150 136 425 412 461 361 345 296 256 218 195 221 206 210 216 213 224 206 222 246 243 210 331 375 365 286 325 328 293 6 142 132 425 393 355 379 346 301 330 226 206 237 209 213 206 279 284 232 205 250 216 224 277 235 368 317 284 311 319 7 138 129 413 417 375 355 333 339 239 224 232 210 234 220 211 243 224 242 230 266 213 209 311 246 314 336 346 279 266 8 149 143 355 413 382 348 339 325 227 230 234 237 260 213 212 237 245 232 250 216 224 349 248 327 325 370 330 248 375

xv = Data(1,2:end);
yv = Data(2:end,1).';
Cm = Data(2:end, 2:end);

figure
contourf(xv, yv, Cm)
colormap(jet)
colorbar
xlabel('X')
ylabel('Y')

EDIT — (1 Aug 2022 at 14:23)

Added the specific colormap and the colorbar call.

.

[Moritz Schäfle]

This is very helpful! Thanks a lot! :-)

[Star Strider]

My pleasure!