1 Invocation

This tool contains command line utilities that perform sample path analysis on data sets representing flow processes provided in csv files and writes its output as png files to the local filesystem.

Invoke it on the command line with

flow <command> <csv-file> [options]

2 Commands

• Analyze: Generates finite-window Little’s Law charts from an CSV file containing id, start_ts, end_ts, and optionally a class column. It produces a full set of long run samplepath flow-metrics charts and writes them under an output directory.

3 Analyze Command

What it does:

1. Parse CLI arguments
2. Create the output directory structure
3. Copy input CSV under scenario
4. Write CLI parameters into the scenario folder
5. Run the sample-path analysis
6. Generate the charts and write to the output directory.
7. Print paths to generated charts

Example

flow analyze events.csv \
  --completed \
  --outlier-iqr 1.5 \
  --lambda-pctl 99 \
  --output-dir charts \
  --scenario weekly_report \
  --clean

Options

CSV Parsing

• csv (positional)
  Path to the CSV. Should contain at least the columns (id,start_ts,end_ts[, class])

• –delimiter (default: ",")
  Optional delimiter override

• –start_column (default: start_ts)
  Name of start timestamp column

• –end_column (default: end_ts)
  Name of end timestamp column

• –date-format (default: None)
  Explicit datetime format string for parsing

Data Filters

Drop rows from the CSV before running the analysis. Useful for isolating subprocesses in the main file. Use with --scenario to save subprocess results.

• –completed (default: False)
  Include only items with end_ts

• –incomplete (default: False)
  Include only items without end_ts

• –classes (default: None)
  Comma-separated list of class tags to include

Outlier Trimming

Remove outliers to see whether the remaining process converges.

• –outlier-hours (default: None)
  Drop items exceeding this many hours in sojourn time

• –outlier-pctl (default: None)
  Drop items above the given percentile of sojourn times

• –outlier-iqr (default: None)
  Drop items above Q3 + K·IQR (Tukey fence)

• –outlier-iqr-two-sided (default: False)
  Also drop items below Q1 − K·IQR when combined with --outlier-iqr

Lambda Fine Tuning

Sometimes it helps to drop early points in the λ(T) chart so the remainder displays on a more meaningful scale.

• –lambda-pctl (default: None)
  Clip Λ(T) to the upper percentile (e.g., use 99 to clarify charts)

• –lambda-lower-pctl (default: None)
  Clip the lower bound as well

• –lambda-warmup (default: 0.0)
  Ignore the first H hours when computing Λ(T) percentiles

Convergence Thresholds

• –epsilon (default: 0.05)
  Relative error threshold for convergence

• –horizon-days (default: 28.0)
  Ignore this many initial days when assessing convergence

Output Configuration

• –output-dir (default: charts)
  Root directory where charts will be written

• –scenario (default: latest)
  Subdirectory inside the output root

• –save-input (default: True)
  Copy the input CSV into the output directory

• –clean (default: False)
  Remove existing charts before writing new results

• –with-event-marks (default: False)
  Show arrival/departure event markers on sample path charts. When enabled, arrivals are shown as purple dots and departures as green dots on the N(t) chart.

Inputs and Outputs

Input Format

The input format is simple.

The csv requires three columns

• id: any string identifier to denote an element/item
• start_ts: the start time of an event
• end_ts: the end time of an event

Additionally you may pass any other columns. They are all ignored for now, except for a column called class which you can use to filter results by event/item type.

• If your csv has different column names, you can map them with --start_column and --end_column options.
• You might need to explicitly pass a date format for the time stamps if you see date parsing errors. The --date-format argument does this.

Results and charts are saved to the output directory as follows:

• The default output directory is “charts” in your current directory.
• You can override this with the –output-dir argument.

See the CLI Documentation for the full list of command line options.

Output Layout

For input events.csv, output is organized as:

<output-dir>/
└── events/
    └── <scenario>/                 # e.g., latest
        ├── input/                  # input snapshots
        ├── core/                   # core metrics & tables
        ├── convergence/            # limit estimates & diagnostics
        ├── convergence/panels/     # multi-panel figures
        ├── stability/panels/       # stability/variance panels
        ├── advanced/               # optional deep-dive charts
        └── misc/                   # ancillary artifacts

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A complete reference to the charts produced can be found in The Chart Reference.