Plotting using x-axis arrays that are not in monotonically increasing order?

Question

Natasha D 2019-3-7

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/448881-plotting-using-x-axis-arrays-that-are-not-in-monotonically-increasing-order

评论： Walter Roberson 2021-1-22

My goal is to plot a curtain profile using imagesc() with the x-axis corresponding to the Latitude values and y-axis to the Altitude. My x-axis data are the latitude points of an instrument orbiting the Earth. In this scenario, the latitude values increase (reaching top of orbit) and then they decrease.

I've been able to successfully plot these profiles for when the latitude values were in increasing/decreasing order but not when they have both scenarious occuring.

Anyone have an idea/code that can fix this error? Thank you!

x = latitude;
y = altitude;
z = data; % (in matrix format)
imagesc(x, y, z)
%Error: x vector must be in increasing order%

3 个评论
显示 1更早的评论隐藏 1更早的评论

Walter Roberson 2019-3-9

在 MATLAB Online 中打开

Perhaps

pcolor(x, y, data)

Natasha D 2019-3-11

Unfortunately the data exceeds the upload size.

I tried pcolor but it isn't giving me what I want it to. Thank you though.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Cris LaPierre 2019-3-9

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/448881-plotting-using-x-axis-arrays-that-are-not-in-monotonically-increasing-order#answer_364620

编辑：Cris LaPierre 2019-3-20

Is your x vector evenly sampled? Without having actual data, my suggestion would be make x=1:length(latitude) and plot that. Then update your xTickLabels to be the actual latitude values.

3 个评论
显示 1更早的评论隐藏 1更早的评论

Cris LaPierre 2021-1-22

The underlying ruler is going to be evenly spaced and monotonically increasing. This is what is used to place your X and Y values.

Imagesc is slightly different in that it uses the row indices as the Y values, and the column indices as the X values. If you want to change the 'direction', you must manipulate the matrix. Perhaps try using fliplr to reverse the x direction, of flipud to revers the y direction.

Walter Roberson 2021-1-22

在 MATLAB Online 中打开

You would not typically need to fliplr or flipud for imagesc. However you might want to

set(gca, 'YDir', 'normal')

The default for imagesc() is YDir reverse, so that data in the low Y indices (lower row) is shown at the top of the display and higher Y indices (higher row) is at the bottom of the display.

请先登录，再进行评论。