gratools pan_ratio

Analyze the ratio between core (shared) and dispensable (specific) segments in your pangenome.

🧬 Core Genome

Segments shared by a high percentage or number of samples. This represents the stable, conserved part of the pangenome.

🧩 Dispensable Genome

Segments specific to a few samples or unique individuals. This represents the accessory or flexible part of the pangenome.

Options

🛠️ View Command Line Options

$ gratools pan_ratio
Welcome to GraTools version: '1.1.0'
@author: GraTools team's
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Please cite our gitlab: https://forge.ird.fr/diade/gratools.git\

Usage: gratools pan_ratio [OPTIONS]
Aliases: ratio

  This command analyzes segments in the GFA to determine the ratio of core
  segments (shared by almost all samples) versus the dispensable ones (present
  in a smaller subset of samples). The thresholds for defining 'core' and
  'dispensable' can be specified as an absolute number of samples or as a
  percentage of the total number of samples embedded in the GFA. A filter on
  segment length can also be applied. Results are displayed in the terminal and
  saved to a CSV file. This command relies on a pre-existing GraTools import of
  the input GFA.
  
  For more details, see the full documentation:
  https://gratools.readthedocs.io/en/latest/commands/pan_ratio.html

Pan Ratio Ratio Options:
  -g, --gfa PATH
     Path to the input GFA file (e.g., myGraph.gfa or myGraph.gfa.gz).
     [required]

  -o, --outdir DIRECTORY
     Output directory for GraTools results. If not specified, results are
     typically placed in a subdirectory within the GFA file's parent directory
     (e.g., 'GraTools-output_<gfa_name>').

  -su, --suffix TEXT
     Custom suffix to append to output filenames. If not provided, a default
     suffix will be generated based on the command line parameters.

  --input-as-number / --input-as-percentage
     Specify whether --shared-min and --specific-max are absolute numbers or
     percentages.  [required]

  -sm, --shared-min TEXT
     Minimal number/percentage of samples embedded in for a segment to be
     'core'.  [required]

  -spm, --specific-max TEXT
     Maximal number/percentage of samples embedded in for a segment to be
     'dispensable'.  [required]

  -fl, --filter-len INTEGER
     Minimal segment length (bp) to be included in the analysis. A value of 0
     means no length filter.  [default: 0]

Logging Options:
  -vv, --verbosity [DEBUG|INFO|ERROR]
     Set the logging verbosity level.  [default: INFO]

  -l, --log-path DIRECTORY
     Directory where the log files will be saved. If not specified, logs will be
     placed in the main output directory (or in a default GraTools log
     location).

Performance Options:
  -t, --threads INTEGER
     Number of threads to be used for parallelizable operations.  [default: 1]

Other options:
  -h, --help
     Show this message and exit.

Usage Example

📊 Basic Ratio Calculation

In this example, we analyze a GFA with 5 samples.

Core threshold: Shared by at least 4 samples (--shared-min 4).
Dispensable threshold: Present in 2 or fewer samples (--specific-max 2).
Filter: Only segments ≥ 50 bp are considered for the filtered stats (--filter-len 50).

$ gratools pan_ratio -g Og_cactus.gfa.gz --input-as-number \
    --shared-min 4 --specific-max 2 --filter-len 50 --threads 4

Output Summary:

─────────────────────────────────────────── Summary ──────────────────────────────────────
Total segments in GFA: 2,354,995
Total segments analyzed: 2,354,995
Total segments passing length filter (≥ 50bp): 210,046 (8.92%)

                         Core vs. Dispensable Segments — Og_cactus
╭────────────────────────────────────────────────────┬───────────┬───────────┬────────────╮
│ Category                                           │     Count │     Total │ Percentage │
├────────────────────────────────────────────────────┼───────────┼───────────┼────────────┤
│ Shared (Core) - Raw                                │ 1,162,062 │ 2,354,995 │     49.34% │
│ Specific (Dispensable) - Raw                       │   891,345 │ 2,354,995 │     37.85% │
│ Shared (Core) - Filtered (Length >= 50bp)          │   195,840 │   210,046 │     93.24% │
│ Specific (Dispensable) - Filtered (Length >= 50bp) │     8,602 │   210,046 │      4.10% │
│ Segments Filtered Out by Length                    │ 2,144,949 │ 2,354,995 │     91.08% │
╰────────────────────────────────────────────────────┴───────────┴───────────┴────────────╯

Understanding the Results

Percentage based on all segments in the GFA.

📦 Raw Statistics

Shared (Core) - Raw: The number of core segments as a percentage of all segments in the GFA.
Specific (Dispensable) - Raw: The number of dispensable segments as a percentage of all segments in the GFA.

Percentage based only on filtered segments (≥ --filter-len).

🔍 Filtered Statistics

Shared (Core) - Filtered: The number of core segments that also meet the length filter, as a percentage of only the filtered segments. This shows the composition of the longer segments.
Specific (Dispensable) - Filtered: The number of dispensable segments that meet the length filter, as a percentage of only the filtered segments.
Filtered Out: The total number and percentage of segments that were excluded from the “Filtered” analysis because they were shorter than the –filter-len value.

Process & Logic

🔢 Threshold Logic

The --shared-min (-sm) and --specific-max (-spm) options specify the number of samples a segment must be found in to be considered part of the “core” or “dispensable” genome, respectively.

Input mode: The user must specify whether the thresholds are :

🔢 Using Absolute Numbers

Use --input-as-number.

Example: --shared-min 4 means the segment must be in 4+ samples to be Core.

📈 Using Percentages

Use --input-as-percentage.

Example: --shared-min 90% means the segment must be in 90% of samples.

🖼️ Visual Diagram

Example: For the command gratools pan_ratio –input-as-number –specific-max 2 –shared-min 4, the minimum number of samples for a segment to be “core” is 4, and the maximum number of samples for it to be “dispensable” is 2.

📏 Length Filtering

The --filter-len (-fl) option excludes short, often uninformative segments from the “Filtered” analysis. This helps focus on structural variations and significant genomic regions.

💡 Pro Tip

In many pangenome graphs, a large number of segments are very short (1-50 bp). Use --filter-len to see the “real” structural core genome, as short segments can sometimes skew the percentage towards core due to graph complexity.

📑 Quick Links

Command Import: gratools import
Related Tool: gratools depth_nodes_stat