Wrong figure caption about hugo-xmin

[yihui]

See https://bookdown.org/yihui/bookdown/figures.html for the requirements on chunk labels.

[psychelzh]

I have read those texts. I made a simpler example. But the caption is still not right (with unnecessary (#fig:load_data_and_visualization) heading).

```{r load_data_and_visualization, message=FALSE, warning=FALSE, fig.cap="Matrix plot of all variables"}
library(tidyverse)
birthsmoke <- read.table("https://onlinecourses.science.psu.edu/stat501/sites/onlinecourses.science.psu.edu.stat501/files/data/birthsmokers.txt", header = TRUE)
plot(birthsmoke)
```

[yihui]

You didn't read it carefully. To quote the documentation on that page:

If you want to cross-reference figures or tables generated from a code chunk, please make sure the chunk label only contains alphanumeric characters (a-z, A-Z, 0-9), slashes (/), or dashes (-).

[psychelzh]

I have changed it without spaces now. You could read my second example.

[psychelzh]

The point here is that the words "(#fig:load_data_and_visualization)" are unnecessary. I do not know why they appear here.

[yihui]

Okay, for the third time: please, please read the documentation carefully. I have copied the relevant part above. It is only one sentence. Please read every word in it.

[psychelzh]

Oh my, I know now. The underscore (_) is not supported. :( I am sorry, but it is very error-prone for newbies if underscore is not supported.