Pair At A Time

pair-at-a-time

Quick Start

• Command: pair-at-a-time
• Local executable: /home/vimalinx/miniforge3/envs/bio/bin/pair-at-a-time
• I/O shape: reads plain text on stdin and writes adjacent token pairs on stdout

When To Use This Tool

• Convert free text into adjacent word pairs for simple co-occurrence or neighbor analysis.
• Normalize punctuation and case before downstream counting, filtering, or sorting.
• Chain after XML / text extraction steps in lightweight EDirect shell pipelines.
• Keep using shell text tools instead of pulling text into Python just to make bigrams.
• Not for paired-end sequencing reads; this is a text-stream wrapper, not a genomics read-pair utility.

Common Patterns

# 1) Adjacent pairs from a sentence
printf 'Alpha beta gamma\n' | pair-at-a-time

# 2) Punctuation is stripped and tokens are lowercased
printf 'BRCA1, TP53; EGFR\n' | pair-at-a-time

# 3) Downstream counting of repeated neighboring pairs
xtract -pattern DocumentSummary -element Title |
pair-at-a-time |
sort | uniq -c | sort -nr

Recommended Workflow

1. Feed the tool plain text on stdin, usually after xtract, sed, tr, or another shell extractor.
2. Assume punctuation will be discarded and alphabetic text lowercased before pairing.
3. Capture stdout directly into sort, uniq -c, or other downstream shell filters.
4. If record boundaries matter, split and process each record separately before calling this wrapper.

Guardrails

• There is no real option parsing: -h or --help produce no useful built-in help text.
• The script depends on the companion helper word-at-a-time being on PATH; invoking pair-at-a-time by absolute path alone can still fail with word-at-a-time: command not found.
• Non-alphanumeric characters are converted to spaces and all alphabetic characters are lowercased.
• Consecutive duplicate tokens are collapsed by uniq before pairing, so foo foo bar becomes foo bar.
• Original line / record boundaries are not preserved; the wrapper effectively pairs across the flattened token stream.