https://github.com/mdsumner/RGDALSQL

DBI GDAL
https://github.com/mdsumner/RGDALSQL

Last synced: about 2 months ago
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DBI GDAL

• Host: GitHub
• URL: https://github.com/mdsumner/RGDALSQL
• Owner: mdsumner
• Created: 2016-07-24T15:05:40.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2020-09-22T11:19:57.000Z (about 4 years ago)
• Last Synced: 2024-06-11T20:50:11.674Z (3 months ago)
• Language: R
• Homepage:
• Size: 275 KB
• Stars: 17
• Watchers: 2
• Forks: 0
• Open Issues: 3
• Metadata Files:
  • Readme: README.Rmd

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README

        
---

output: github_document

editor_options: 

  chunk_output_type: console

---

```{r, echo = FALSE}

knitr::opts_chunk$set(

  collapse = TRUE,

  comment = "#>",

  fig.path = "README-"

)

```

[![Travis-CI Build Status](https://travis-ci.org/mdsumner/RGDALSQL.svg?branch=master)](https://travis-ci.org/mdsumner/RGDALSQL)

[![Coverage Status](https://img.shields.io/codecov/c/github/mdsumner/RGDALSQL/master.svg)](https://codecov.io/github/mdsumner/RGDALSQL?branch=master)

## RGDALSQL

WIP

```{r}

library(RGDALSQL)

f = system.file("extdata/continents", package = "RGDALSQL")

db <- dbConnect(RGDALSQL::GDALSQL(), f)

dbSendQuery(db, "SELECT * FROM continent WHERE FID < 1")

res <- dbSendQuery(db, "SELECT * FROM continent WHERE continent LIKE '%ca'")

dbFetch(res)

(res <- dbReadTable(db, "continent"))

dplyr::tbl(db, "continent")

```

## Limitations

* currently read-only, so no temporary tables for `compute()`

* no temporary tables in non-DB drivers (i.e. GPKG is ok, SHP is not)

* no sub-queryies in non-DB drivers (i.e. no collapse for SHP or GDB)

filter, arrange, summarize, transmute, mutate, ok but cannot be chained for nested sub-queries

```{r}

library(dplyr)

tbl(db, "continent") %>% dplyr::filter(continent == "Australia")

tbl(db, "continent") %>% dplyr::filter(continent %in% c("Australia", "Antarctica")) %>% collect() 

```

Try OSM PBF. 

```{r, eval=FALSE}

# wget https://download.geofabrik.de/europe/albania-latest.osm.pbf

f <- fs::path_expand("~/albania-latest.osm.pbf")

pbf <- dbConnect(RGDALSQL::GDALSQL(),f)

## we have to use a normalized path 

## (vapour doesn't do this yet, but GDALSQL will do it *when connecting*, 

## currently maintains the input DSN)

pbf

# db_list_tables(pbf)

tbl(pbf, "points") 

# Source:   table [?? x 11]

# Database: GDALSQLConnection

   osm_id  name     barrier highway   ref   address is_in place man_made other_tags                            `_ogr_geometry_`  

                                                                       

 1 154606… ""       ""      "traffic… ""    ""      ""    ""    ""       "\"crossing\"=>\"traffic_signals\",\… \"uncontrolled\""      \"traffic_signals\",\… \"uncontrolled\""      \"traffic_signals\",\… \"uncontrolled\",\"su… \"peak\""               \"peak\""               \"peak\",\"wikidata\"=… \"peak\",\"prominence\… % filter(osm_id == "53292") %>% select(`_ogr_geometry_`, type)

# Source:   lazy query [?? x 2]

# Database: GDALSQLConnection

  type     `_ogr_geometry_`                                                      

                                                                    

1 boundary 

```

```{r}

f <- "inst/extdata/shapes.gpkg"

conn <- dbConnect(RGDALSQL::GDALSQL(),f)

conn

dbListTables(conn)

x <- dbSendQuery(conn, "SELECT * FROM sids WHERE SID74 < 10")

tbl(conn, "sids") %>% 

  arrange(desc(AREA))  %>% 

  transmute(a = AREA *8, geom, AREA) %>% 

  filter(a > 1.62)  %>% 

  show_query()

## with SHP we can't do subquery

f <- system.file("shape/nc.shp", package = "sf")

conn <- dbConnect(GDALSQL(), f)

## but the special variables are there

tbl(conn, "nc") %>% arrange(OGR_GEOM_AREA)

tbl(conn, "nc") %>% arrange(OGR_GEOM_AREA, FID) %>% show_query()

## FAILS because subquery

tbl(conn, "nc") %>% mutate(aa = AREA) %>% transmute(a1 = FID) %>% show_query()

## ok because a single statement

tbl(conn, "nc") %>% transmute(a1 = FID, aa = AREA) %>% collect()

```