在 R markdown 中对齐左图标题

Question

figure captions in R markdown to PDF are centered by default. here's an example:

---
title: "test"
output: pdf_document
---


![Caption](test_pic.jpg)

(where test_pic.jpg is a local jpg file)

any ideas how to align the caption left?

I found how to change the size, using special attributes:

![Caption](test_pic.jpg){#id .class width=30%} 

but what's the special attribute to align left?

Answer 1

Yes, to align the caption left in PDF output from Rmarkdown we can use one chunk per image, with knitr::include_graphics in the chunk to display the image (this creates the LaTeX for the image), and a little LaTeX that controls the alignment of the caption:

---
title: "Untitled"
output:
    pdf_document:
        includes:
            in_header: file.tex
---

Here are some examples of `knitr::include_graphics` with the code chunk options being used to control the size and location:

```{r fig.align="left",  out.width = "50%", fig.cap="left-aligned"}
knitr::include_graphics("rrtools-steps-carbon.png")
```

```{r fig.align="center",  out.width = "30%", fig.cap="center aligned"}
knitr::include_graphics("rrtools-steps-carbon.png")
```

```{r fig.align="right",  out.width = "20%", fig.cap="right aligned"}
knitr::include_graphics("rrtools-steps-carbon.png")
```

And here is file.tex , which should be in the same directory as the RMarkdown file:

\usepackage[font=small,format=plain,labelfont=bf,up,textfont=normal,up,justification=justified,singlelinecheck=false]{caption}

And here's a screenshot of part of the output: