How to hold figure position with figure caption in pdf output of knitr?

Question

I am using knitr (1.9.5 and 1.9.17) and rmarkdown (0.5.3.1), and would like to hold figure position in the pdf output. The generated pdf file is working fine when chunk option fig.pos="H" is used.

However, the figure position is not hold when fig_caption: yes is set in the yaml header.

How should I fix this problem? Thanks for any suggestions.

EDIT:

After learning the float environment of Latex. I add float package into header.

\usepackage{float} 

But the generated tex file always use htbp in the figure environment regard to any fig.pos options are used. After manually changing htbp to H, positions of all figures are hold.

This is my example of rmd file:

--- title: "Untitled" output:   pdf_document:     fig_caption: yes     includes:         in_header: mystyles.sty ---  # Section 1   Note that the `echo = FALSE` parameter was added to the code chunk to prevent printing of the R code that generated the plot.  Note that the `echo = FALSE` parameter was added to the code chunk to prevent printing of the R code that generated the plot.  Note that the `echo = FALSE` parameter was added to the code chunk to prevent printing of the R code that generated the plot.  Note that the `echo = FALSE` parameter was added to the code chunk to prevent printing of the R code that generated the plot.   ```{r fig1, echo=FALSE, fig.height=8.5, fig.pos="H"} plot(cars) ```  # Section 2  More test  ```{r fig2, echo=FALSE, fig.height=8.5, fig.pos="H"} plot(cars) ```  # Section 3  ```{r fig3, echo=FALSE, fig.height=8.5, fig.pos="H"} plot(cars) ```  More test 

Answer 1

For me adding the float package and then \floatplacement{figure}{H} in YAML solved the issue like :

--- title: "test" date: "`r Sys.Date()`" output:    pdf_document :     keep_tex: true     number_sections: true header-includes:  \usepackage{booktabs}  \usepackage{longtable}  \usepackage{array}  \usepackage{multirow}  \usepackage[table]{xcolor}  \usepackage{wrapfig}  \usepackage{float}  \floatplacement{figure}{H} --- 

Answer 2

As Andrew pointed out, this fig.pos doesn't work in chunks, but it does work if it is put in global options:

```{r global_options, include=FALSE} knitr::opts_chunk$set(fig.pos = 'H') ``` 

EDIT: the above apparently used to work and needs \usepackage{float} in the preamble:

header-includes:  \usepackage{float} 

See also here and the Cookbook for some other ways.