MATLAB evaluation codes used for the 2nd CAFA challenge. The CAFA2 paper is published in Genome Biology, and you can also find the latest arXiv version here.
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"Gold standard" data. This is proteins with known annotation in SwissProt.
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Sequences in FASTA format.
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Annotations (MFO terms for example) for each of these sequences. This data needs to be prepared ahead of time as a two-column CSV file (delimited by
TAB
)<sequence ID> <GO term ID>
where
<sequence ID>
would be of any ID systems (e.g., UniProt accession number), as long as they are consistent with those used in the FASTA file.
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NCBI BLAST tool (used 2.2.29+ for this document)
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Query sequences in FASTA format. Query sequences are the unannotated proteins targeted for the CAFA Challenge.
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STEP 1: Load annotations of "gold standard" sequences.
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Load ontology structure(s)
Ontologies need to be loaded into a specific MATLAB structure which will be later used in evaluation. Here we provide two "adapters" for (i) OBO files or (ii) parsed plain-text files.
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Load OBO files
ont = pfp_ontbuild('ontology.obo');
Note that a typical gene ontology OBO file contains all three GO ontologies (i.e., MFO, BPO, and CCO), therefore,
pfp_ontbuild
returns a cell of THREE ontology strcutures instead:onts = pfp_ontbuild('go.obo');
By default, they are ordered as BPO, CCO, MFO, alphabetically. You can also double check the
.ont_type
field of each returning structure. -
Load plain-text files
If you have already parsed an ontology, you can also save its term description and structure into the following two files and then load them into the same MATLAB structure as if using
pfp_ontbuild
:ont = pfp_loadont('terms.tsv', 'relationship.tsv');
where
terms.tsv
is a two column file contains<term ID>
and<term description>
;relationship.tsv
is a three column file contains<term ID> <relationship> <term ID>
, (e.g.,GO:XXXXXXX is_a GO:YYYYYYY
). Both files are delimited byTAB
and do not have header lines.
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Load annotations onto the ontology structure(s)
Once
ont
is created, you can load a list of sequence annotations using terms in this ontology.oa = pfp_oabuild(ont, 'annotation.dat');
where
annotation.dat
is a two column tab-delimited file having<sequence ID> <term ID>
annotation pairs in each line.
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STEP 2: Prepare BLAST results
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Build a Blast database from the fasta-formatted "gold standard" data from Requirements above:
makeblastdb -in <gold_standard.fasta> -out <gold_standard_MFO> -dbtype prot
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Run
blastp
on the query sequences against the "gold standard" sequences by setting output format to be the following:blastp -query <query_protein_sequences.fasta> -db <gold_standard_MFO> -outfmt "6 qseqid sseqid evalue length pident nident" -out blastp.out
Using the
-num_threads
flag forblastp
can speed up your query.blastp
should produce output similar to this:1A1L2_HUMAN TEX37_HUMAN 0.47 107 23.364 25 1A1L2_HUMAN GHRA_ECOLI 0.68 102 29.412 30 1A1L2_HUMAN RFC_ECOLI 1.5 105 23.810 25 1A1L2_HUMAN DAPAT_ARATH 3.0 133 21.053 28 1A1L2_HUMAN NCAP_VSIVA 5.6 72 26.389 19 1A1L2_HUMAN KDIS_RAT 5.8 51 29.412 15 1A1L2_HUMAN TLH1_SCHPO 6.9 61 32.787 20 1A1L2_HUMAN CASPC_MOUSE 7.3 168 20.833 35 1A1L2_HUMAN TLH2_SCHPO 7.5 61 32.787 20 1A1L2_HUMAN YIBL_ECOLI 8.4 36 44.444 16 1A1L2_HUMAN ARAP3_MOUSE 9.0 67 29.851 20 2A5B_HUMAN 2A5A_MOUSE 0.0 464 72.629 337 2A5B_HUMAN 2A5A_HUMAN 0.0 424 75.472 320 2A5B_HUMAN 2A5E_HUMAN 0.0 464 72.629 337 2A5B_HUMAN 2A5E_BOVIN 0.0 464 72.629 337 2A5B_HUMAN 2A51_CAEEL 0.0 445 66.067 294 2A5B_HUMAN 2A5G_HUMAN 0.0 407 70.270 286 ...
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Load the tabular output file (
blastp.out
as shown above) into MATLAB:B = pfp_importblastp('blastp.out');
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STEP 3: Build the BLAST predictor
Run the follow command in MATLAB to get a prediction structure:
blast = pfp_blast(qseqid, B, oa);
where
qseqid
is a cell list of query sequences on which you need scores. Note that it can be just a subset of all those you BLAST'ed.B
is the structure imported step 2, whileoa
is the ontology annotation structure loaded in step 1.Also, extra options can be specified as additional arguments so as to choose which feature you would like to use for creating BLAST predictions. By default, it used
sid
: sequence identity. See the documentation inpfp_blast.m
for more details. Thus,blast
will be the BLAST predictor in MATLAB for evaluation.
To build a naive predictor, all you need is the ontology annotation
structure oa
that you have as in the step 1 of making a BLAST predictor.
Then run the following in MATLAB:
naive = pfp_naive(qseqid, oa);
Evaluation codes are provided mainly for reproducing results in CAFA2
experiments. However, one may also use a subset of codes under matlab/
to
evaluate their own protein function predictors.
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Represent protein sequences using CAFA2 target ID systems (e.g.,
T96060000019
). Please checkbenchmark/
folders for lists of benchmark proteins that needs to be covered. -
Save predictions in CAFA2 submission format according to CAFA rule. Although, headers (including
AUTHOR
,MODEL
,KEYWORDS
andACCURACY
) and footer (END
) are optional. (Seecafa_import.m
for details)
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Load ontologies into MATLAB structures.
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You can use pre-built MATLAB structure for the same ontologies used in CAFA2 evaluation, which are located as
*.mat
files underontology/
folder. -
We also provide functions for loading user specified ontologies, see
pfp_ontbuild.m
. Note that it is suggested to use pre-built ontologies in order to compare results against published methods.
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Prepare ground-truth annotations.
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Similarly, ground-truth annotations for CAFA2
3681
benchmark proteins are pre-built and saved as*.mat*
files underbenchmark/groundtruth/
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User specified annotations can be built using
pfp_oabuild.m
, note that proteins have to use the same ID system as used for predictions. Also, see the comments for input arguments inpfp_oabuild.m
for details.oa = pfp_oabuild(ont, <annotation file>);
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Load predictions into MATLAB structures.
This can be done by execute the following command in MATALB:
pred = cafa_import(<prediction file>, ont, false);
with the 2nd argument
ont
as the ontology structure built in the first step. We specify the 3rd argument to befalse
indicating our<prediction file>
don't contain headers and footer. -
Load benchmark protein IDs.
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Protein IDs must be loaded as a
cell
array. You can use the following function:benchmark = pfp_loaditem(<benchmark list file>, 'char');
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Various CAFA2 benchmark protein lists are prepared under
benchmark/lists/
, load any one that meets your requirement.
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Evaluation. (sequence-centered)
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The easiest way to get an performance evaluation is to use the following function (in the case of F-max):
fmax = pfp_seqmetric(benchmark, pred, oa, 'fmax');
See
pfp_seqmetric.m
for other metrics. -
Alternatively, you can compute confusion matrix so as to expose intermediate variables:
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Make a confusion matrix structure
cm = pfp_seqcm(benchmark, pred, oa);
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Convert the
cm
structure to metrics of interest, here "precision-recall"seq_pr.metric
would have 101 precision-recall pairs corresponding to 101 thresholds from0.00
up to1.00
with step size0.01
. You can use it to draw a PR curve.seq_pr = pfp_convcmstruct(cm, 'pr');
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Due to CAFA rules, the organizers of CAFA cannot release the submitted predictions from participants. Therefore, it is technically not possible to replicate exact results (figures and tables) in the CAFA2 paper. Also, this repository is not originally designed to be a software that is reusable as a whole for protein function prediction tasks in general or even for future CAFA challenges. As a result, the pipeline is not fully automatized and manual input is necessary occasionally.
Please also notice that this pipeline is only tested on Linux version of
MATLAB (2016b), it is not guaranteed to work on other OS (code might have to
be adapted accordingly). We also used Bioinformatics toolbox for topological
ordering of ontology terms (graphtopoorder
) in some Matlab functions.
However, it should be fairly easy to implement your own version if this
toolbox is not available.
With that being said, we provide scripts along with a minialist guideline to assist researchers who would like to evaluate their own methods using CAFA2 benchmarks (along with their annotations by the time stated in the paper) so as to compare their performances against CAFA2 baselines and possibly against other methods.
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Download this repository to your local filesystem, say
/path/to/cafa2_repo
, hereafter<cafa2repo>
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Prepare an empty folder that have write permission, say
/path/to/another/folder
, hereafter,<mydir>
, for holding evaluation results. -
In Matlab, change working directory to
<cafa2repo>/matlab
and setup<mydir>
:cd <cafa2repo>/matlab; cafa_setup('<cafa2repo>', '<mydir>');
This command sets up empty folders inside
<mydir>
where intermediate/final results will sit. -
Place your plain-text prediction file into
<mydir>
.Note that prediction files should be using CAFA format:
<target ID> <term ID> <score>
for each line but without HEADER (those lines start withMODEL
,AUTHOR
,KEYWORDS
etc.) or FOOTER (theEND
line). Filename is suppose to beM001
(M
followed by three digits) andM002
,M003
so on so forth if you have more than one methods to be evaluated. Then copy/move them into<mydir>/consolidated
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Filter predictions. This step will filter out predictions on proteins that are not in any benchmarks, which could greatly reduce the size of intermediate files and processing speed. In Matlab
cafa_driver_filter('<mydir>/consolidated', '<mydir>/filtered', '<cafa2repo>/benchmark/lists/xxo_all_typex.txt');
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Import plain-text predictions into Matlab structures, so that they can be reused for different evaluation tasks (e.g., different metrics, different benchmarks, etc.) Let's use MFO as an example:
load <cafa2repo>/ontology/MFO.mat; cafa_driver_import('<mydir>/filtered', '<mydir>/prediction/mfo', MFO);
Notice that up until now, these steps only need to be executed once. Each following particular evaluation tasks is specified using a single plain-text job configuration file
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Make a job configuration file according to your needs, please use the example file:
<cafa2repo>/config/example.job
as a template. Basically, you need to change and accordingly; specify what metric you are using, which evaluation mode, etc. And save the modified configuration file at/path/to/config.job>
, hereafter,<config>
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Pre-evaluation. This step is essential for sequence-centric evaluations so as to avoid repeated calculations. It evaluates/stores metrics (e.g., precision/recall) for each protein to
<mydir>/seq-centric
.Note that if you have multiple benchark lists on which you want to evaluate, it is suggested to create a union of all those lists and to do a pre-evaluation on the union just once.
cafa_driver_preeval('<config>');
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Evaluation. This step performs the actual evaluation, and the runtime depends on how many methods/metrics you specified in the configuration. If the number of methods exceeds 8, it will start in parallel mode. Note that all results will be saved into a subfolder under
<mydir>/evaluation/<subfolder>
, it will be named after<ontology>_<category>_<type>_<mode>
, let's simply call it<eval_res>
.cafa_driver_eval('<config>');
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Make a register table file according to your needs, please use the example file:
<cafa2repo>/config/register.tab
as a template. You can also look at the comments in<cafa2repo>/matlab/cafa_parse_register.m
for reference. We would assume the modified file will be saved somewhere and be refered to as<register>
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Collect results. This step should output figures and tables in
<eval_res>
folder.cafa_driver_result('<eval_res>', '<register>', 'BN4S', 'BB4S', 'all');
As a final note, please refer to the comments part in each Maltab function for detailed input/output descriptions. They can be accessed by typing
help <function name>
in Matlab console.
The source code used in this CAFA2 evaluation package is licensed under the MIT license.