Parallel workflow configuration class

WorkflowConfig is a class that stores parallel workflow configuration parameters. Configurations can be saved/imported to run workflows in parallel.

class plantcv.parallel.WorkflowConfig

Class methods

Save a configuration file that can be modified and imported to run workflows in parallel.


  • Parameters:
    • config_file (str, required): path/name of output configuration file
  • Context:
    • Used to create a configuration file that can be edited and imported

Import a configuration file.


  • Parameters:
    • config_file (str, required): path/name of input configuration file
  • Context:
    • Used to import configuration settings from a file

Validate parameters/structure of configuration data.


  • Parameters:
    • None
  • Context:
    • Used to run validation checks on configuration settings


input_dir: (str, required): path/name of input images directory (validates that it exists).

json: (str, required): path/name of output JSON data file (appends new data if it already exists).

filename_metadata: (list, required): list of metadata terms used to construct filenames. for example: ["plantbarcode","timestamp"]. Supported metadata terms are listed here.

workflow: (str, required): path/name of user-defined PlantCV workflow Python script (validates that it exists).

include_all_subdirs: (bool, default = True): If False, only images directly in input_dir (no subdirectories) will be analyzed.

img_outdir: (str, default = "."): path/name of output directory where images will be saved.

tmp_dir: (str, default = None): path/name of parent folder for the temporary directory, uses system default . temporary directory when None.

start_date: (str, default = None): start date used to filter images. Images will be analyzed that are newer than the start date. In the case of None all images prior to end_date are processed. String format should match timestampformat.

end_date: (str, default = None): end date used to filter images. Images will be analyzed that are older than the end date. In the case of None all images after start_date are processed. String format should match timestampformat.

imgformat: (str, default = "png"): image file format/extension.

delimiter: (str, default = "_"): image filename metadata term delimiter character. Alternatively, a regular expression for parsing filename metadata.

metadata_filters: (dict, default = None): a dictionary of metadata terms (keys) and values, images will be analyzed that have the associated term and value.

timestampformat: (str, default = '%Y-%m-%d %H:%M:%S.%f'): a date format code compatible with strptime C library. See strptime docs for supported codes.

writeimg: (bool, default = False): save analysis images to img_outdir if True.

other_args: (list, default = []): list of other arguments required by the workflow (e.g. ["--input1", "value1", "--input2", "value2"]).

coprocess (str, default = None): coprocess the specified imgtype with the imgtype specified in metadata_filters (e.g. coprocess NIR images with VIS).

cleanup: (bool, default =True): remove temporary job directory if True.

append: (bool, default = True): if True will append results to an existing json file. If False, will delete previous results stored in the specified JSON file.

cluster (str, default = "LocalCluster"): LocalCluster will run PlantCV workflows on a single machine. All valid options currently are: "LocalCluster", "HTCondorCluster", "LSFCluster", "MoabCluster", "OARCluster", "PBSCluster", "SGECluster", and "SLURMCluster". See Dask-Jobqueue for more details.

cluster_config: (dict, default: see below ): a dictionary of parameters and values used to configure the cluster for parallel processing locally or remotely.

metadata_terms: (dict, default: as-is): a dictionary of metadata terms used to assign values in image filenames (or metadata files) to metadata terms (should not be modified).

Cluster configuration

Dask is used to parallelize PlantCV image analysis workflows using both dask.distributed and dask_jobqueue. In Dask a cluster is a type of computing environment, which could either be local or a remote resource (in this case a computing cluster managed by a scheduler).

First, we need to define the type of cluster to use. LocalCluster is the simplest setup and creates a pool of computing resources on the machine where we will run the plantcv.parallel functions.


The concept of "local" and "remote" is relative to the PlantCV program, not the user. In other words, LocalCluster could be used to run PlantCV on a single remote machine if this task were submitted to a remote computing environment (e.g. cloud, campus cluster, etc.). This is the standard approach PlantCV has used in older versions.

All other currently supported cluster types listed above allow the user to configure PlantCV to interface with a job scheduling platform and distribute image analysis workflows across a computing resource (e.g. campus cluster).


The cluster name supplied to the cluster setting must match one of the keywords above exactly (case-sensitive).

After defining the cluster, parameters are used to define the size of and request resources from the given computing environment. These settings are defined in the cluster_config parameter. We define by default the following parameters:

n_workers: (int, required, default = 1): the number of workers/slots to request from the cluster. Because we generally use 1 CPU per image analysis workflow, this is effectively the maximum number of concurrently running workflows.

cores: (int, required, default = 1): the number of compute cores per workflow. This should be left as 1 unless a workflow is designed to use multiple CPUs/cores/threads.

memory: (str, required, default = "1GB"): the amount of memory/RAM used per workflow. Can be set as a number plus units (KB, MB, GB, etc.).

disk: (str, required, default = "1GB"): the amount of disk space used per workflow. Can be set as a number plus units (KB, MB, GB, etc.).

log_directory: (str, optional, default = None): directory where worker logs are stored. Can be set to a path or environmental variable.

local_directory: (str, optional, default = None): dask working directory location. Can be set to a path or environmental variable.

job_extra: (dict, optional, default = None): extra parameters sent to the scheduler. Specified as a dictionary of key-value pairs (e.g. {"getenv": "true"}).


n_workers is the only parameter used by LocalCluster, all others are currently ignored. n_workers, cores, memory, and disk are required by the other clusters. All other parameters are optional. Additional parameters defined in the dask-jobqueu API can be supplied.


import plantcv.parallel

# Create a WorkflowConfig instance
config = plantcv.parallel.WorkflowConfig()

#if you want to reuse a configuration file you can import it after creating an instance

# Change configuration values directly in Python as needed. At a minimum you must specify input_dir, json, filename_metadata, workflow.
config.input_dir = "./my_images"
config.json = "output.json"
config.filename_metadata = ["plantbarcode", "timestamp"]
config.workflow = ""

# Check for errors

# If it passes, save your configuration

You may also edit your configuration file directly in a text editor, just remember that JSON syntax applies. See Workflow Parallization tutorial for examples

To run with a config file you can use the following:

python --config my_config.json

Remember that python and need to be in your PATH, for example with Conda environment. On Windows you will need to specify the whole path to

python %CONDA_PREFIX%/Scripts/ --config my_config.json