Digitize your chemical reaction image into a machine-readable representation.
V.0 · IBM Research Zurich

Table of contents

• Description
• Step by step
• Benchmarking
• Installation
• Models - Training - Evaluation - Inference
• Contributing
• Creators
• Thanks
• Citing

Description

From a chemical reaction image, detect and classify molecules, text and arrows by using a Vision Transformer (DETR). The detections are then translated into text "OCR" or into SMILES. The direction of the reaction is detected and preserved into the output file.

TRY THE COMPLETE VERSION OUT AT: https://rxn.app.accelerate.science/rxn/ under "Optical Chemical Recognition".

Output:

Reaction X

SMILES:
C=Cc1ccc2[nH]cc(C[C@H](N)C(=O)OF)c2c1>>C/C=C(\\C)CN1C2CCC(=O)[C@]1(C)Cc1c2[nH]c2ccc(C)cc12.O>>molecule8>>molecule5>>BCc1ccc2[nH]c3c(c2c1-c1c(O)ccc(C)c1C1=C(C)C2CC4/C(=C\\C)CN2C(C1)C4CC)CC1C(CC)C24CC3N1[C@@H]2/C4=C/C.C.CC=O.CC=O>>C=C1CC2(C#N)C3(C)CC1C1CCNC12CC1=C3Cc2ccc(C)c(-c3c([O-])ccc4[nH]c5c(c34)CC3C[C@H]4C5(C)CC(C)([C@@H](C)CCO)C34CC3CC3)c21

Step by step

1 - Objects detection - ViT

A DETR model with a ResNet50 backbone is used to detect the objects in the image. Classes to be found = ["molecules","arrows","text", "+ symbols"]. Images of type "png" are feed as input and bounding boxes corresponding to the objects locations in a tensor type as well as its respective label are the returned outputs.

Input Image

Detections

Training Dataset

Syntetic Dataset consisting of 50k images that are randomly created to simulate the real-world reactions publications distribution.

Training Parameters

• Learning Rate: 1e-4
• Learning Rate Backbone: 1e-5
• Learning Rate Drop: 22 epochs
• Weight Decay: 1e-5
• Epochs: 30
• Clip Max. Norm.: 0.1
• Dropout: 0.1

Multi Head Self-Attention

Encoder-decoder attention files can be found in the Backend-Output-detections path.

2 - OCR

OCR model from DocTr library was trained on chemical-related data generated from US chemical patents. To come up with the training data set, the Text Recognition Data Generator tool was used. The resulting weights were used to extract textual information from text detections.

3 - MolVec

Towards recognizing the information present in the molecule objects detected, we utilized the open-access user interface MolVec.

4 - Pixel Magic

In pursuance of preserving the real path of the whole reaction, the direction of the arrows detected was extracted.

Output Files

A randomly selected small sample of the test set is evaluated under the folders "test_results" of each approach. DETR, FRCNN and RetinaNet. Check qualitatevly the performance of the models in there.

Aggregating the aforementioned steps outcome, we can reconstruct JSON and text files.

{
    "arrow11": {
        "prev_mol": "CCCC#N.CCCC[Al](CC(C)C)CC(C)C",
        "text": ["-duction of nit-ile", "Coordination of nitrog- pair to the ilum-"],
        "post_mol": "CCCC#[N+3]1(CCC)C(C)(C)C[AlH2]1(O)CC(C)C"
    },
    "arrow5": {
        "prev_mol": "CCCC#[N+3]1(CCC)C(C)(C)C[AlH2]1(O)CC(C)C",
        "text": ["Delivery of hyd-ide to the nitr-- carbon"],
        "post_mol": "CCC/C=N/[Al](CC(C)C)CC(C)C"
    },
    "arrow7": {
        "prev_mol": "CCC/C=N/[Al](CC(C)C)CC(C)C",
        "text": ["H20","Formation o"],
        "post_mol": "CCCC=O"
    }
}

Reaction X

SMILES:
C=Cc1ccc2[nH]cc(C[C@H](N)C(=O)OF)c2c1>>C/C=C(\\C)CN1C2CCC(=O)[C@]1(C)Cc1c2[nH]c2ccc(C)cc12.O>>molecule8>>molecule5>>BCc1ccc2[nH]c3c(c2c1-c1c(O)ccc(C)c1C1=C(C)C2CC4/C(=C\\C)CN2C(C1)C4CC)CC1C(CC)C24CC3N1[C@@H]2/C4=C/C.C.CC=O.CC=O>>C=C1CC2(C#N)C3(C)CC1C1CCNC12CC1=C3Cc2ccc(C)c(-c3c([O-])ccc4[nH]c5c(c34)CC3C[C@H]4C5(C)CC(C)([C@@H](C)CCO)C34CC3CC3)c21

Benchmarking

The synthetic training data set was benchmarked with well-established CNNs and a feature detector approach. As a one-stage detector, RetinaNet. As a two-stages detector, Faster-RCNN. However, DETR with default training schedules performed slightly better. Check the metrics comparison in the folder: plots.

mAP score per class and model (%)

Installation

• Make sure to have all requirements.txt installed.

• git clone https://github.com/facebookresearch/detr.git

• git clone https://github.com/mindee/doctr.git

Models

Download the DETR_Resnet50 model and move the file to DETR/detr/output/checkpoint.pth

Create synthetic data set and train DETR:

• Follow steps in arrow_78/README.md file.

Evaluation

• DETR/detr/:
  • python3 main.py --batch_size 8 --no_aux_loss --eval --resume "output/checkpoint.pth" --arrow_path "images/val/" --output_dir "output/"

Inference

• DETR/detr/:
  • python3 attention_DETR.py --resume output/checkpoint.pth

End-to-End OChemR (From image to JSON)

• Backend/:
  • Store detections and visualize encoder-decoder attention in --output_dir/--detection_dir folder and JSON files in --output_dir/:
    • python3 main.py --data_path images/ --resume /detr/output/checkpoint.pth --detection_dir detections/ --output_dir output/ --device_detr cpu

Contributing

DETR - https://github.com/facebookresearch/detectron2

DocTr - https://github.com/mindee/doctr

MolVec - https://github.com/ncats/molvec

Creators

Mark Martori Lopez

Thanks

This thesis would not have been possible without the guidance of Dr. Daniel Probst as my supervisor, whom I deeply thank. Throughout the writing of this dissertation I have received a great deal of support by all my colleagues at the Accelerated DiscoveryTeam of IBM Research Zurich.

Citing

@software{M.Martori2022,
  author = {Martori, Mark and Probst, Daniel},
  month = {6},
  title = {{Machine Learning approach for chemical reactions digitalisation.}},
  url = {https://github.com/markmartorilopez/,
  version = {0.0},
  year = {2022}
}