How to convert the 'source index' into a vector data column

[detjoker]

How to use R convert the 'source index' into a vector data column which is :index(a vector value),START_X START_Y

library(rgdal)
list.files("ljz_network.gdb","Export_Output")
ljz<-readOGR("ljz_network.gdb","Export_Output" )
ogrInfo (dsn = ,"Export_Output",encoding = NULL,use_iconv = FALSE,require_geomType = NULL,morphFromESRI = NULL, dumpSRS = FALSE, enforce_xy = NULL)
print(ljz)    

back:
geometry | START_X | START_Y | Shape_Length |
MULTILINESTRING((13530030 3636987 ...)) | 13530033 | 3636987 | 44.304098
...

network<-readOGR("ljz_network.gdb","Export_Output")
ID<-1:nrow(network)
df<-data.frame(ID,c(network))

back:
ID | START_X | START_Y | Shape_Length |
1 | 13530033 | 3636987 | 44.304098 |
2 | 13530033 | 3636987 | 30.773139 |
...

sp_df<-st_sfc(df(list(cbind(c(ID),c(network)))))

Error in df(list(cbind(c(ID), c(network)))) :
argument "df1" is missing, with no default

It always fail to make a vector type into my ID column...

[DavoWW]

Hi @detjoker,
Welcome to the RStudio Community Forum.

Try this:

df <- cbind(data.frame(ID=rownames(data)), data)

The row names are made into a one-column intermediate dataframe before column binding.
Also check out the rownames_to_column() function from the tibble package (loaded as part of library( tidyverse).)

[detjoker]

rownames_to_column(data)

Error in rownames_to_column(data) :
Not all is.data.frame(df) are TRUE

Thanks your advice!! It shows that there are still some problems that I did not realize that need to be solved...

[etiennebr]

I’m not sure if I understand what you want to do, but I would recommend using sf and tidyverse packages to explode or combine coordinates.

I don’t have your original data, but you should be able to use read_sf() to load them.

library(tidyverse)
library(sf)

# You should be able to use the following line
#read_sf("ljz_network.gdb",layer = "Export_Output")

# I'll have to make data, hopefully their structure matches what you have
lines <- st_sf(
  id = 1:2,
  geometry = st_as_sfc(c(
    "LINESTRING(0 0, 2 3, 1 4, 0 3)", 
    "LINESTRING(0 0, -2 3, -1 4, 0 3)"))
) 
lines
#> Simple feature collection with 2 features and 1 field
#> geometry type:  LINESTRING
#> dimension:      XY
#> bbox:           xmin: -2 ymin: 0 xmax: 2 ymax: 4
#> CRS:            NA
#>   id                       geometry
#> 1  1 LINESTRING (0 0, 2 3, 1 4, ...
#> 2  2 LINESTRING (0 0, -2 3, -1 4...

plot(lines$geometry)

# explode lines
points <- lines %>% 
  rowwise() %>% 
  mutate(
    coordinates = list(st_coordinates(geometry)),
  ) %>% 
  unnest(coordinates) %>% 
  group_by(id) %>% 
  mutate(
    x = coordinates[, 1],
    y = coordinates[, 2],
    l1 = coordinates[, 3],
    # MULTILINESTRINGS would have an additional column for each part
    order = row_number(),
    coordinates = NULL  # drop the raw coordinate column
  ) %>% 
  ungroup()

# make points
points <- points %>% 
  rowwise() %>% 
  mutate(
    geometry_point = st_sfc(list(st_point(c(x, y))))
  )
points
#> Simple feature collection with 8 features and 5 fields
#> Active geometry column: geometry
#> geometry type:  LINESTRING
#> dimension:      XY
#> bbox:           xmin: -2 ymin: 0 xmax: 2 ymax: 4
#> CRS:            NA
#> # A tibble: 8 x 7
#> # Rowwise: 
#>      id               geometry     x     y    l1 order geometry_point
#> * <int>           <LINESTRING> <dbl> <dbl> <dbl> <int>        <POINT>
#> 1     1   (0 0, 2 3, 1 4, 0 3)     0     0     1     1          (0 0)
#> 2     1   (0 0, 2 3, 1 4, 0 3)     2     3     1     2          (2 3)
#> 3     1   (0 0, 2 3, 1 4, 0 3)     1     4     1     3          (1 4)
#> 4     1   (0 0, 2 3, 1 4, 0 3)     0     3     1     4          (0 3)
#> 5     2 (0 0, -2 3, -1 4, 0 3)     0     0     1     1          (0 0)
#> 6     2 (0 0, -2 3, -1 4, 0 3)    -2     3     1     2         (-2 3)
#> 7     2 (0 0, -2 3, -1 4, 0 3)    -1     4     1     3         (-1 4)
#> 8     2 (0 0, -2 3, -1 4, 0 3)     0     3     1     4          (0 3)

plot(points$geometry_point)

# make lines from points
points %>% 
  arrange(l1) %>% 
  group_by(id) %>% # could add part if doing multilinestring
  summarise(
    geometry_line = st_cast(st_combine(geometry_point), "LINESTRING")
  ) 
#> `summarise()` ungrouping output (override with `.groups` argument)
#> Simple feature collection with 2 features and 1 field
#> geometry type:  LINESTRING
#> dimension:      XY
#> bbox:           xmin: -2 ymin: 0 xmax: 2 ymax: 4
#> CRS:            NA
#> # A tibble: 2 x 2
#>      id          geometry_line
#>   <int>           <LINESTRING>
#> 1     1   (0 0, 2 3, 1 4, 0 3)
#> 2     2 (0 0, -2 3, -1 4, 0 3)

^{Created on 2021-09-22 by the reprex package (v0.3.0)}

[detjoker]

Thank you very much for your reply, your answer helped me a lot.