ATMOSPHERIC CHEMISTRY/CARBON AND HYDROCARBON COMPOUNDS
WORKING GROUP FOR PLANETARY SYSTEM NOMENCLATURE

```r
keyword_pairs <- nasa_keyword %>% 
  pairwise_count(keyword, id, sort = TRUE, upper = FALSE)

keyword_pairs
```

```
## # A tibble: 13,390 x 3
##    item1         item2                       n
##    <chr>         <chr>                   <dbl>
##  1 OCEANS        OCEAN OPTICS             7324
##  2 EARTH SCIENCE ATMOSPHERE               7318
##  3 OCEANS        OCEAN COLOR              7270
##  4 OCEAN OPTICS  OCEAN COLOR              7270
##  5 PROJECT       COMPLETED                6450
##  6 EARTH SCIENCE ATMOSPHERIC WATER VAPOR  3142
##  7 ATMOSPHERE    ATMOSPHERIC WATER VAPOR  3142
##  8 EARTH SCIENCE OCEANS                   2762
##  9 EARTH SCIENCE LAND SURFACE             2718
## 10 EARTH SCIENCE BIOSPHERE                2448
## # ... with 13,380 more rows
```

```r
set.seed(1234)
keyword_pairs %>%
  filter(n >= 700) %>%
  graph_from_data_frame() %>%
  ggraph(layout = "fr") +
  geom_edge_link(aes(edge_alpha = n, edge_width = n), edge_colour = "royalblue") +
  geom_node_point(size = 5) +
  geom_node_text(aes(label = name), repel = TRUE,
                 point.padding = unit(0.2, "lines")) +
  theme_void()
```

![(\#fig:plotcounts)Co-occurrence network in NASA dataset keywords](08-nasa-metadata_files/figure-latex/plotcounts-1.pdf)