您正在关注此问题

您将在关注的内容源中看到更新。
您可能会收到电子邮件，具体取决于您的通信预设项。

How do I convert a linear scale array to a logarithmic without getting negative values?

6 次查看（过去 30 天）

显示更早的评论

farzad 2020-7-6

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values

⋮

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values

评论： farzad 2020-7-9

Hi All

I need to plot ( bar plot) values, and on the X axis , I want to convert them to logarithmic, but the values <1 become negative. how to avoid and fix it ?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Rik 2020-7-6

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927206

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927206

You would have to remove those.

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

madhan ravi 2020-7-6

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#answer_461837

⋮

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#answer_461837

Replace < 1 with nan.

14 个评论
显示 12更早的评论隐藏 12更早的评论

farzad 2020-7-6

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927236

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927236

this is what I do , I take the log immediately when I am plotting I doubt I can do what you say, how do I do that ?

f=barh(y, log(x), 'basevalue', min(x));

Rik 2020-7-6

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927281

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927281

编辑：Rik 2020-7-6

f=barh(y, max(0,log(x)), 'basevalue', 0);

If you want to replace values, you will have to store the intermediate result, or write a function that does that.

farzad 2020-7-7

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927719

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927719

thank you very much for your answer. yes this is right but : I think something is wrong.

Because : here we are actually taking the logarithm of the X axis values. so if the maximum is 10^ 4 , the max on the logarithmic will be 4.

but I meant only changing the scale of showing the values , therefore , not touching the actual X values, but changing the X values. the same way it is done in Excel.

Rik 2020-7-7

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927737

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927737

You can change the axis if you like. What exactly do you want to happen?

farzad 2020-7-7

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927770

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927770

please see the attached. the distances of the lines is in logarithmic scale. this is how you can do in Excel :

madhan ravi 2020-7-7

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927779

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927779

set(gca, 'XScale', 'log')

farzad 2020-7-7

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927824

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927824

Thank you ! it worked on scaling , but all the bars disappeared ! I wanted to use the log scale to see the small bars better !

Rik 2020-7-7

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927851

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927851

In X or Y?

farzad 2020-7-7

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927938

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_927938

the scaling should be only along X, cause the bars are along X axis

farzad 2020-7-8

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_929870

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_929870

Any opinions on why the bars disappear ? the divisions start from 10^-1 to 10^4 and I should have a graph in this range

farzad 2020-7-9

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_930485

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_930485

any ideas ?

madhan ravi 2020-7-9

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_930488

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_930488

Nope

farzad 2020-7-9

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_930560

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_930560

That's a pity, I'm stuck

farzad 2020-7-9

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_930767

⋮

链接

此评论的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/560483-how-do-i-convert-a-linear-scale-array-to-a-logarithmic-without-getting-negative-values#comment_930767