Introduction

ClassyFire is a web-based application for automated structural classification of chemical compounds.

The classyfireR R package provides access to the ClassyFire RESTful API for retrieving existing compound classifications and submitted structures to the web-server for classification.

Installation

classyfireR can be installed from CRAN or, for the latest development version, directly from GitHub using the remotes package.

install.packages('classyfireR')

remotes::install_github('aberHRML/classyfireR')

Retrieving Classifications

To retrieve classifications that are already available simply provide an InChI key to the get_classification function.

library(classyfireR)
#> Loading required package: magrittr

Classification <- get_classification('BRMWTNUJHUMWMS-LURJTMIESA-N')
#> ✔ BRMWTNUJHUMWMS-LURJTMIESA-N

Classification
#> ── ClassyFire Object ───────────────────────────────────── classyfireR v0.3.8 ── 
#> Object Size: 18.2 Kb 
#>  
#> Info: 
#> • InChIKey=BRMWTNUJHUMWMS-LURJTMIESA-N
#>   
#> • [H][C@](N)(CC1=CN(C)C=N1)C(O)=O
#>   
#> • Classification Version: 2.1
#>   
#> kingdom : Organic compounds
#> └─superclass : Organic acids and derivatives
#>   └─class : Carboxylic acids and derivatives
#>     └─subclass : Amino acids, peptides, and analogues
#>       └─level 5 : Amino acids and derivatives
#>         └─level 6 : Alpha amino acids and derivatives
#>           └─level 7 : Histidine and derivatives

The result of each classification is stored in a single S4 (ClassyFire) object. To retrieve multiple classification, simply iterate over a vector of InChI Keys’

InChI_Keys <-
  c('BRMWTNUJHUMWMS-LURJTMIESA-N',
    'MDHYEMXUFSJLGV-UHFFFAOYSA-N',
    'MYYIAHXIVFADCU-QMMMGPOBSA-N')


Classification_List <- purrr::map(InChI_Keys, get_classification)
#> ✔ BRMWTNUJHUMWMS-LURJTMIESA-N
#> ✔ MDHYEMXUFSJLGV-UHFFFAOYSA-N
#> ✔ MYYIAHXIVFADCU-QMMMGPOBSA-N

Submit Multiple Queries

For classification submission using SMILES, this can be performed by supplying multiple SMILES to the submit_query function. The results from all of the inputs, will be returned to a single S4 Query class.

If any of the inputs are not successfully classified, then these will be stored in the unclassified slot and can be accessed using the unclassified accessor method.

Input <- c(MOL1 = 'CCCOCC', MOL2 = 'CNC(CC1=CN=CN1)C(=O)O', MOL3 = 'CXN')

Query <-
  submit_query(label = 'query_test',
               input = Input,
               type = 'STRUCTURE')
               
               
Query
── ClassyFire Query Object ──────────────────────────────── classyfireR v0.3.7 ── 
Object Size: 27.6 Kb 
 
2 structures classified 
• MOL1 : InChIKey=NVJUHMXYKCUMQA-UHFFFAOYSA-N
• MOL2 : InChIKey=CYZKJBZEIFWZSR-UHFFFAOYSA-N

1 structures not classified 
• MOL3 : CXN               



unclassified(Query)

 MOL3 
"CXN" 

Accessor Methods

There are a series of accessor methods which will work with either object type to return results from a specific slot in the object.


classification(Classification)
#> # A tibble: 7 × 3
#>   Level      Classification                       CHEMONT          
#>   <chr>      <chr>                                <chr>            
#> 1 kingdom    Organic compounds                    CHEMONTID:0000000
#> 2 superclass Organic acids and derivatives        CHEMONTID:0000264
#> 3 class      Carboxylic acids and derivatives     CHEMONTID:0000265
#> 4 subclass   Amino acids, peptides, and analogues CHEMONTID:0000013
#> 5 level 5    Amino acids and derivatives          CHEMONTID:0000347
#> 6 level 6    Alpha amino acids and derivatives    CHEMONTID:0000060
#> 7 level 7    Histidine and derivatives            CHEMONTID:0004311


meta(Classification)
#> $inchikey
#> [1] "InChIKey=BRMWTNUJHUMWMS-LURJTMIESA-N"
#> 
#> $smiles
#> [1] "[H][C@](N)(CC1=CN(C)C=N1)C(O)=O"
#> 
#> $version
#> [1] "2.1"


chebi(Classification)
#>  [1] "L-alpha-amino acid (CHEBI:15705)"                  
#>  [2] "imidazolyl carboxylic acid (CHEBI:38307)"          
#>  [3] "aralkylamine (CHEBI:18000)"                        
#>  [4] "imidazoles (CHEBI:24780)"                          
#>  [5] "organic aromatic compound (CHEBI:33659)"           
#>  [6] "amino acid (CHEBI:33709)"                          
#>  [7] "carbonyl compound (CHEBI:36586)"                   
#>  [8] "carboxylic acid (CHEBI:33575)"                     
#>  [9] "carboxylic acid anion (CHEBI:29067)"               
#> [10] "organonitrogen heterocyclic compound (CHEBI:38101)"
#> [11] "pnictogen molecular entity (CHEBI:33302)"          
#> [12] "organic molecular entity (CHEBI:50860)"            
#> [13] "organic oxide (CHEBI:25701)"                       
#> [14] "alkylamine (CHEBI:13759)"                          
#> [15] "organic molecule (CHEBI:72695)"                    
#> [16] "histidine derivative (CHEBI:24599)"                
#> [17] "chemical entity (CHEBI:24431)"                     
#> [18] "organooxygen compound (CHEBI:36963)"               
#> [19] "peptide (CHEBI:16670)"                             
#> [20] "organonitrogen compound (CHEBI:35352)"             
#> [21] "alpha-amino acid (CHEBI:33704)"                    
#> [22] "organic heterocyclic compound (CHEBI:24532)"       
#> [23] "azole (CHEBI:68452)"                               
#> [24] "nitrogen molecular entity (CHEBI:51143)"           
#> [25] "amine (CHEBI:32952)"                               
#> [26] "oxygen molecular entity (CHEBI:25806)"             
#> [27] "primary amine (CHEBI:32877)"

Working with a local cache

A local cache can be used to save queries too, which will speed up workflows where large numbers of entities are being classified each time, and will mean that the API only queries the server, when absolutely necessary.

A local cache can easily be created using the following command

ClassyFireDB <- RSQLite::dbConnect(RSQLite::SQLite(), 'ClassyFireCache.db')

Before running the get_classifcation function, a connection to the cache needs to be created.

ClassyFireCache <- open_cache(dbname = 'ClassyFireCache.db')

Then pass the cache variable as the conn argument in the get_classification function.

get_classification('BRMWTNUJHUMWMS-LURJTMIESA-N', conn = ClassyFireCache)

Acknowledgements

If you use classyfireR you should cite the ClassyFire publication

Djoumbou Feunang Y, Eisner R, Knox C, Chepelev L, Hastings J, Owen G, Fahy E, Steinbeck C, Subramanian S, Bolton E, Greiner R, and Wishart DS. ClassyFire: Automated Chemical Classification With A Comprehensive, Computable Taxonomy. Journal of Cheminformatics, 2016, 8:61.

DOI: 10.1186/s13321-016-0174-y