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Histogram Mode

Histogram Mode provides tools for generating histograms and analyzing data distributions.

Purpose

Histogram Mode is designed for:

  • Creating histograms to understand data distributions
  • Quality assessment and outlier detection

Keyboard Reference

Data Selection and Histogram Generation

Key Action Description
Enter Select Dataset Select the dataset under cursor for histogram (when in tree view)
h Show Histogram Compute and display histogram of selected dataset
H Save Histogram Compute histogram and save to file

Direct Configuration

Key Action Description
e Edit Config Jump to configuration window for advanced editing
b Edit Bins Edit the number of histogram bins
x Toggle X-Scale Toggle x-axis between linear and logarithmic scale
y Toggle Y-Scale Toggle y-axis between linear and logarithmic scale
r Reset Configuration Reset histogram configuration to defaults

Direct Configuration Editing (When in Config Window)

Key Action Description
Enter Edit Parameter Edit the parameter under cursor
q Exit Config Return to tree view

Mode Control

Key Action Description
q Exit Histogram Mode Return to Normal Mode (when in tree view)

Entering Histogram Mode

From Normal Mode, press H to enter Histogram Mode.

Creating Histograms

Basic Histogram Workflow

  1. Navigate to dataset of interest
  2. Enter Histogram Mode (H)
  3. Select dataset (Enter) - selects the data under cursor for histogram
  4. Generate histogram (h) - computes and "shows" the histogram 4.5. Save histogram (H) - computes and saves the histogram to file
  5. Examine distribution in histogram panel

Dataset Selection

Select Dataset (Enter)

  • When focused on a dataset in the tree view, press Enter to select it
  • Sets default binning, labels, and scales (linear x and y, 50 bins, key as x-label)
  • Displays configuration in the histogram panel

Histogram Generation

Show Histogram (h)

  • Computes histogram using current configuration
  • Displays histogram in an external window (using matplotlib)

Save Histogram (H)

  • Computes histogram as above
  • Prompts for filename
  • Saves histogram to file (using whatever format specified by filename extension, e.g., PNG, PDF)

Histogram Configuration

Direct Configuration Bindings

Histogram Mode provides direct key bindings for common configuration tasks, eliminating the need to enter a separate configuration mode for basic adjustments:

Edit Number of Bins (b)

  • Directly edit the number of histogram bins in the prompt
  • Updates configuration immediately
  • No need to navigate to configuration window

Toggle X-Scale (x) / Toggle Y-Scale (y)

  • Instantly toggle x/y-axis between linear and logarithmic scale
  • Validates data range is computed before toggling
  • Checks data compatibility when switching to log scale (must be strictly positive)
  • Shows clear error if log scale is incompatible with data (negative/zero values)
  • Updates configuration display immediately

Advanced Configuration Window

Edit Config (e)

  • Switches to the full configuration window for advanced editing
  • Allows editing of all parameters
  • Navigate parameters with arrow keys or Vim motion keys
  • Press Enter to edit parameter under cursor
  • Press q to return to tree view

Configuration Reset

Reset Configuration (r)

  • Restores all parameters to defaults
  • Clears dataset selection
  • Closes any open histogram windows
  • Returns to clean state for new analysis

Error Handling

Common Issues

Non-Numeric Data

  • Clear error messages for string or compound datasets
  • Suggestions for appropriate data types
  • Guidance on data selection

Empty Datasets

  • Graceful handling of zero-length arrays
  • Appropriate error messages
  • Suggestions for data validation

Data Range Validation

  • Data range not yet computed: Operations like toggling scales or editing bins require the data range to be computed first. If you see "data range not yet computed", ensure you've selected a dataset with Enter. You may need to wait for the background computation to complete for large datasets.

Logarithmic Scale Errors

  • Negative values with log x-scale: Error message indicates data contains negative values incompatible with logarithmic x-axis. Shows exact minimum value for diagnosis.
  • Zero values with log x-scale: Error message indicates data contains zero values incompatible with logarithmic x-axis. Shows exact minimum value for diagnosis.
  • Zero histogram counts with log y-scale: Error message indicates some bins have zero counts, incompatible with logarithmic y-axis. Shows exact minimum count for diagnosis.
  • Immediate validation: Scale compatibility is checked immediately when toggling to log scale, providing instant feedback.

Tips

Start Simple

Begin with default histogram settings, then refine configuration based on initial results. Use direct key bindings (b, x, y) for quick adjustments.

Bin Count Guidelines

For most datasets, automatic binning (50 bins) works well. Press b to adjust: increase bins for more detail, decrease for smoother curves.

Log Scale Constraints

Logarithmic scales require strictly positive values. The system will prevent you from using log scales with negative or zero data and display a clear error message.