Question

我有一份类似这样的文件：

```{r, include = F}
require(data.table)

dt <- data.table(
  A = c(1, 4, 1, 4, 2, 4, 8),
  B = c(2, 2, 3, 4, 3, 1, 5)
)
```


```{r, echo = F}
col <- "A"

knitr::asis_output(paste0("### Column ", col, "\n"))

knitr::asis_output("Counts\n")

dt[, .(n = .N), by = col]

knitr::asis_output("Statistics\n")

summary(dt[, get(col)])
```


```{r, echo = F}
col <- "B"

knitr::asis_output(paste0("### Column ", col, "\n"))

knitr::asis_output("Counts\n")

dt[, .(n = .N), by = col]

knitr::asis_output("Statistics\n")

summary(dt[, get(col)])
```

虽然这很好，但很明显，这是非常重复的。我尝试使用循环而不是复制粘贴，如下所示：

```{r, echo = F}
for (col in c("A", "B")) {
  knitr::asis_output(paste0("### Column ", col, "\n"))

  knitr::asis_output("Counts\n")

  dt[, .(n = .N), by = col]

  knitr::asis_output("Statistics\n")

  summary(dt[, get(col)])
}
```

然而，这根本不打印输出。如何在RMarkdown文档中循环并生成markdown和R输出？

Answer 1

print结果需要summary声明。您的代码将更改为以下只有print语句添加到summary输出的内容：

```{r, echo = F}
for (col in c("A", "B")) {
  print(knitr::asis_output(paste0("### Column ", col)))

  print(knitr::asis_output("Counts"))

  print(dt[, .(n = .N), by = col])

  print(knitr::asis_output("Statistics"))

  print(summary(dt[, get(col)]))
}
```

这会产生以下结果：

## [1] "### Column A"
## attr(,"class")
## [1] "knit_asis"
## attr(,"knit_cacheable")
## [1] NA
## [1] "Counts"
## attr(,"class")
## [1] "knit_asis"
## attr(,"knit_cacheable")
## [1] NA
##    A n
## 1: 1 2
## 2: 4 3
## 3: 2 1
## 4: 8 1
## [1] "Statistics"
## attr(,"class")
## [1] "knit_asis"
## attr(,"knit_cacheable")
## [1] NA
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   1.000   1.500   4.000   3.429   4.000   8.000 
## [1] "### Column B"
## attr(,"class")
## [1] "knit_asis"
## attr(,"knit_cacheable")
## [1] NA
## [1] "Counts"
## attr(,"class")
## [1] "knit_asis"
## attr(,"knit_cacheable")
## [1] NA
##    B n
## 1: 2 2
## 2: 3 2
## 3: 4 1
## 4: 1 1
## 5: 5 1
## [1] "Statistics"
## attr(,"class")
## [1] "knit_asis"
## attr(,"knit_cacheable")
## [1] NA
##    Min. 1st Qu.  Median    Mean 3rd Qu.    Max. 
##   1.000   2.000   3.000   2.857   3.500   5.000

您可能希望在打印时重新格式化并删除属性。

修改

根据@ user2554330的建议，这是一个使用knitr::knit_print的示例：

```{r, echo = F} for (col in c("A", "B")) { knitr::knit_print(paste0("### Column ", col)) knitr::knit_print("Counts") knitr::knit_print(dt[, .(n = .N), by = col]) knitr::knit_print("Statistics") knitr::knit_print(summary(dt[, get(col)])) } ```

，它提供以下输出

## [1] "### Column A" ## [1] "Counts" ## A n ## 1: 1 2 ## 2: 4 3 ## 3: 2 1 ## 4: 8 1 ## [1] "Statistics" ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 1.000 1.500 4.000 3.429 4.000 8.000 ## [1] "### Column B" ## [1] "Counts" ## B n ## 1: 2 2 ## 2: 3 2 ## 3: 4 1 ## 4: 1 1 ## 5: 5 1 ## [1] "Statistics" ## Min. 1st Qu. Median Mean 3rd Qu. Max. ## 1.000 2.000 3.000 2.857 3.500 5.000

修改2

以下替代解决方案将更密切地印刷SO所要求的内容。它全局删除“##”前缀并将其添加回data.frame（即仅在需要的地方）。它还使用cat代替knitr::knit_print以避免打印数组索引（即[1]）。

```{r, echo = F, comment=NA} for (col in c("A", "B")) { cat(paste0("Column ", col), "\n") cat("Counts\n") ## Add comment prefix tdf <- as.data.frame(dt[, .(n = .N), by = col]) ## Convert to data.frame for printing rownames(tdf) <- paste("## ", 1:nrow(tdf)) ## Add comments for printing. knitr::knit_print(tdf) cat("Statistics\n") ## Add comment prefix knitr::knit_print(summary(dt[, get(col)])) } ```

以下输出更多是SO的要求（根据对此帖的评论）。它在data.frame输出前面加上“##”，但摘要输出没有“##”前缀;如果需要，可以添加。

Column A Counts A n ## 1 1 2 ## 2 4 3 ## 3 2 1 ## 4 8 1 Statistics Min. 1st Qu. Median Mean 3rd Qu. Max. 1.000 1.500 4.000 3.429 4.000 8.000 Column B Counts B n ## 1 2 2 ## 2 3 2 ## 3 4 1 ## 4 1 1 ## 5 5 1 Statistics Min. 1st Qu. Median Mean 3rd Qu. Max. 1.000 2.000 3.000 2.857 3.500 5.000

在RMarkdown代码块中循环

1 个答案: