问:在rmarkdown html中的for循环中创建传单地图 [英] Q: Create leaflet map in for loop in rmarkdown html

问题描述

我正在尝试在rmarkdown文件中创建带有for循环的传单地图.

I am trying to create a leaflet map with a for-loop in an rmarkdown file.

这是一个最小的示例:

---
title: "Test"
output: html_document
---

```{r quakes, echo=F}
data(quakes)
library(leaflet)

for (i in c(10:20))
{
leaflet(data = quakes[1:5 & quakes$stations == i,]) %>% addTiles() %>%
  addMarkers(~long, ~lat, popup = ~as.character(mag))
}
```

此代码没有任何输出.单独运行Leaflet命令(并将i替换为整数)时，它可以工作.我也尝试了打印命令，但这也不起作用.

I do not get any output with this code. When running the leaflet command alone (and replacing the i with an integer) it works. I also tried the print command, but that didn't work either.

有人知道我该怎么做吗?

Any idea how I can do this?

推荐答案

您已经使它有些复杂了.

you have complicated it a little bit.

看到您必须创建一个传单，并通过从唯一的站点中选择经度和纬度在其上应用标记.

See you have to create a leaflet and apply markers on top of it by selecting longitudes and latitudes from unique stations.

但是在这里，您正在循环创建传单.并且还需要在循环中添加图块，这是主要问题.

But here you are creating leaflets in a loop. And also adding tiles in a loop which is the main problem.

现在，您可以创建一个传单，并在循环外添加addTiles，并在循环中添加addMarkers，但实际上您根本不需要for循环，只需一次添加所有标记.

Now you can create a leaflet and addTiles out of the loop and addMarkers in a loop but you dont actually need a for loop at all and add all the markers in one go.

distinct_by_stations<-distinct(quakes,stations) #dplyr is needed for 'distinct'

使用上述过滤器数据集作为数据创建传单并添加标记

leaflet(data = distinct_by_stations) %>% addTiles() %>% addMarkers(~long,~lat,popup=~as.character(mag))

在rpubs上查看正在工作的.rmd

See the working .rmd here at rpubs

http://rpubs.com/dhawalkapil/quakesdata

R块工作

```{r quakes, echo=T}
data(quakes)
library(leaflet)
library(dplyr)

distinct_by_stations<-distinct(quakes,stations)
leaflet(data = distinct_by_stations) %>% addTiles() %>% addMarkers(~long,~lat,popup=~as.character(mag))
```

具有多个地图

让我们在年份上添加一列.然后，我们将不得不使用htmltools::tagList，如@NicE所述.分割年份"并使用lapply

With Multiple Maps

Let's add a column on years. Then we will have to use htmltools::tagList as explained by @NicE. Split on 'year' and use lapply

```{r quakes, echo=T,results='asis'}
data(quakes)
library(leaflet)
library(dplyr)
library(htmltools)
##Add A Random Year Column
quakes$year=sample(2006:2015,length(quakes),replace=TRUE)
createMaps<-function(x){
        distinct_by_stations<-distinct(x,stations)
        lflt<-leaflet(data = distinct_by_stations) %>% addTiles() %>% addMarkers(~long,~lat,popup=~as.character(mag))
}

htmltools::tagList(lapply(split(quakes,quakes$year),function(x){createMaps(x)}))
```

在上面的相同网址中查看更新rpubs.

See the update rpubs in the same url above.

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