DCT Chart - ASCII Data Visualization

Generate simple ASCII histograms from data file columns.

When to Use

Use this skill when you need to:

•Quickly visualize value distributions
•Create terminal-friendly charts
•Analyze categorical data frequencies
•Get a quick histogram without external tools
•Share visualizations in text format

Installation

bash

which dct || go build -o dct && chmod +x ./dct

Usage

bash

dct chart [file] [column_index] [flags]

Arguments

•file: Data file path (optional)
•column_index: 0-based column index to chart (default: 0)

Flags

•-w, --width <chars>: Width of chart in characters (default: auto)

Examples

Basic Usage

Chart first column:

bash

dct chart data.csv

Chart specific column (0-based index):

bash

dct chart data.csv 2

Custom Width

Wider chart:

bash

dct chart sales.csv 1 -w 80

Compact chart:

bash

dct chart data.csv 0 -w 40

Different File Types

Chart from Parquet:

bash

dct chart data.parquet 3

Chart from JSON:

bash

dct chart data.json 0

Output Format

Displays an ASCII histogram with:

•Column values on the left (Y-axis labels)
•Bar representation using box-drawing characters
•Count/frequency on the right
•Box border around the chart

Example output:

code

            ┌─ histogram of 'sales.csv' ──────────────────────────┐
    ProductA ┤ ╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍ 156 │
    ProductB ┤ ╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍ 98 │
    ProductC ┤ ╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍ 73 │
    ProductD ┤ ╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍ 45 │
    ProductE ┤ ╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍╍ 22 │
             └───────────────────────────────────────────────────┘

How It Works

•Reads the specified column from the data file
•Groups values and counts frequencies
•Sorts by frequency (descending)
•Renders ASCII bar chart scaled to fit terminal

Best Practices

•Column indexing: Remember column index is 0-based (first column = 0)
•Use -w flag: Adjust width to fit your terminal
•Categorical data: Works best with categorical or binned data
•High cardinality: Top values are shown; long tail may be truncated
•Preview first: Use dct-peek to see column names before charting

Use Cases

Sales Analysis

bash

# Chart sales by product
dct chart sales.csv 0 -w 60

# Chart revenue distribution
dct chart orders.csv 2 -w 80

Data Exploration

bash

# Quick distribution check
dct peek data.csv -n 5
dct chart data.csv 1 -w 50

Log Analysis

bash

# Chart status codes from logs
dct chart logs.csv 3 -w 40

Limitations

•Shows top N values (high-cardinality columns truncate)
•ASCII art has limited resolution
•Best for categorical or discrete numeric data
•Continuous numeric data should be pre-binned

Column Selection Workflow

bash

# 1. Preview file to see columns
dct peek data.csv

# 2. Note the column index (0-based)
#    Columns: id | name | category | amount
#    Index:    0    1        2         3

# 3. Chart desired column
dct chart data.csv 2 -w 60

Integration Examples

In Shell Scripts

bash

#!/bin/bash
# Generate charts for all columns in a file
file="data.csv"
num_cols=$(head -1 "$file" | tr ',' '\n' | wc -l)
for i in $(seq 0 $((num_cols - 1))); do
    echo "Column $i:"
    dct chart "$file" $i -w 50
    echo
done

With Other Tools

bash

# Filter data then chart
grep "ERROR" logs.csv | dct chart - 1 -w 40

# Save chart to file
dct chart data.csv 0 -w 80 > chart.txt

Related Skills

•dct-peek: Preview column names before charting
•dct-profile: Get detailed statistics about the column
•dct-infer: Understand column types

Terminal Tips

•Charts look best in terminals with UTF-8 support
•Use wider terminals (-w 100+) for detailed views
•Pipe to less -S for wide charts: dct chart data.csv 0 -w 120 | less -S