Meshgrid for logarithmic scales matlab answers matlab central. The log of negative real values is equal to the log of the positive value, plus pi1i that is the result is complex. All values in the colormap indexing array that are less than or equal to cmin map to the first row in the colormap. The contour matrix, c, is an optional output argument returned by contour, contour3, and contourf. Learn more about logarithmic, nonlinear, non, linear, log, scale matlab. I have a workaround where i plot the log data in the contour and replace the x and ytick labels of the plot. Im currently trying to plot data using contourfx,y,z, where z values are ranging from 0. Add an accurate colorbar to your filled contour plot. Rotation of a contour plot matlab answers matlab central. Matlab lesson 10 log scale plots university of new south. Matlab evaluates the variable in the base workspace to generate the xdata. But regardless, id like to only have the y axis as a log scale, not the whole plot.
For example, direction,reverse reverses the color scale. Create a second contour plot and use zindex to highlight contour lines at every other integer value. Contour plot color scaling matlab answers matlab central. If, hypothetically, it were able to display with complex coordinates, where would you want the values displayed.
If you are working with polar axes, then this option sets thetalimmode and rlimmode to manual. However, what is interesting to see is between 0 and 0. Contourf and log color scale demonstrate use of a log color scale in contourf. I would like to make 3d plot using mesh in which one axis should be on a logarithmic scale. Hi, i would like to know how can i apply the same thing for the contourf. Xyz contour plot with colormap from second z and custom.
The logspace function is especially useful for creating frequency vectors. Jul 09, 2014 if i use imrotate for the matrix i have of the contour, the resultant contour doesnt actually rotate by the same angle which i specify 37 deg in the example, image3 and more over sometimes the width of the plot decreases. When you set yscale to log, then internally it would take the log of the negative values you have, and would found that the log is complex. Logarithmic colorbar for contour plot a lot of my data ranges orders of magnitude, and can be very hard to depict using standard matlab functions like imagesc, contourf, contour, etc. Create plots programmatically using graphics functions or interactively using the plots tab at the top of the matlab desktop. Generate logarithmically spaced vector matlab logspace. If you link a variable, then matlab does not update the xdata values immediately. Here are some matlab code of active contour model, which are collected from the internet.
Ive read up on the scatter function, but havent seen how to plot any of those axes in a logarithmic fashion. Use only the colors in the center of the hot colormap by setting the color axis scaling to a range much larger than the range of values in matrix z. Contour chart appearance and behavior matlab mathworks italia. Aug 09, 2012 i would like to make contourf plot but in such a way that the colorbar is in log scale because i have quite a large range of values in my data. Line plots, log plots, and function plots line plots are a useful way to compare sets of data or track changes over time. Create a figure window with ui axes and assign the uiaxes object to the variable ax. May 24, 20 however setting the range of b or a to b0. Ive read all the help on contour and contourf functions and colorbar but nothing useful can be found there. The column and row indices of z are the x and y coordinates in the plane, respectively. For illustrations of some of the types of plots you can create programmatically, see types of matlab plots. This example shows how to change the colors used in a filled contour plot. Not all types of charts support modifying the colorbar appearance. Plotting a scatter plot with logarithmic axes matlab.
The values in y can be numeric, datetime, duration, or categorical values. This matlab function creates a plot using a base 10 logarithmic scale for the y axis and a linear scale for the xaxis. Please see more details on creating and customizing color fill contour in the 3d and contour graphing chapter. To create a plot with a linear scale on the xaxis and a log base 10 scale on the xaxis you can use the function semilogx. However i am not happy with result because the labeling does work during zoom.
This term refers to the fact that the plot is logarithmically scaled in both axes. Define scale in contourplot matlab answers matlab central. I know their general values, say between 010, 0, however i calculate them. For example do you want the complex portion of the coordinate to be treated as time, and the display should automatically cycle through a time period perhaps every 2pi seconds with the negative values being displayed for one frame on each occasion that the complex value projected. The function is the logarithmic equivalent of linspace and the. The matlab mfile used to create this plot is experr. Im currently doing some simulation work for a physics honours project and i have data generated into vectors that id like to plot.
Matlab automatically selects the contour lines to display. You can plot the data in a 2d or 3d view using either a linear or a logarithmic scale. Display eight contour levels of the peaks function and label the contours. Set axis limits and aspect ratios matlab axis mathworks. Downloads trial software contact sales pricing and licensing how to buy. Jul 06, 2012 the ability to create a logarithmic scale colormap or colorbar is not available in matlab. The loglog function plots coordinates on a log scale by setting the xscale and yscale properties of the axes to log. Is it possible to make contour graph with log scale. Mar 16, 2012 a lot of my data ranges orders of magnitude, and can be very hard to depict using standard matlab functions like imagesc, contourf, contour, etc. Find a way to set the logarithmic scale programmatically and let matlab worry about the isolines. For example, you can compare sets of data, track changes in data over time, or show data distribution.
Logarithmic scale for colorbar matlab answers matlab central. Semilog plot yaxis has log scale matlab semilogy mathworks. Logarithmic scale for colorbar matlab answers matlab. To create a plot using a log base 10 scale for both the xaxis and and the yaxis you can use the function loglog. Thank you again for you quick reply,the log scale trick label of the 3d surf is not the same for color bar, this is the problem the colorbar colors and values i.
The clabel function uses values from c to display labels for 2d contour lines. Previously i did this by setting the yscale property of the underlying colorbar axes, but this no longer works with the new graphics system. Is it possible to make contour graph with log scale colorbar. How do i create a logarithmic scale colormap or colorbar. Is it possible to make contour graph with a semilogy scale. To force an update of the data values, use the refreshdata function. Learn more about logarithmic, nonlinear, non, linear, log, scale. Add a line plot to the axes by specifying the uiaxes object as the first input argument for the plot function.
Nov 03, 2014 does anybody know how to get nice contourlabels clabel in plots with logaritmic axes. A fellow customer posted the following suggested workaround for this problem on our usenet newsgroup, comp. The ability to create a logarithmic scale colormap or colorbar is not available in matlab. I sometimes require a plot which has a colorbar with a log scale. I would like to make contourf plot but in such a way that the colorbar is in log scale because i have quite a large range of values in my data. By default, there is no linked variable so the value is an empty character vector. Is there a way to use meshgrid and mesh to do this.