File Saving

The save command exports processed data to text files. It supports two modes:

  1. columns - export selected expressions for each page into separate files
  2. table - export one shared axis with one column per page into a single table file

Basic Usage 

save columns --path <path-template> --columns <expr1> [<expr2> ...] [options]

save table --path <path-template> --axis <axis-expr> --column <data-expr> [options]

Modes Overview

Mode Output pattern Typical use
columns One file per page Save processed columns (e.g. k, chi, expressions)
table One file per target path, with one column per page Build comparison tables for plotting/analysis outside EstraPy

Save columns

Exports one file for each page. Each file contains the requested expression columns evaluated on that page.

save columns --path <path-template> --columns <expr1> [<expr2> ...] [options]

Options

Option Description
--path <path-template>
-p <path-template>		 Output path template (required). Supports metadata placeholders like {.fn}.
--columns <expr1> [<expr2> ...]
-c ...		 Expressions to export as columns (required).
--select <expr> Boolean expression used to filter rows before writing.
--domain <domain>
-d <domain>		 Domain used to resolve expressions (default: reciprocal).

Behavior

  • Expressions in --columns are evaluated per row.
  • --select keeps only rows where the expression is true.
  • One file is generated per page (after path template expansion).
  • Header includes EstraPy version, project name, original filename, analysis date, and metadata.

Example 

save columns --path "processed/{.fn}_chi.dat" --columns k chi --domain reciprocal

save columns --path "processed/{.fn}_windowed.dat" --columns k "chi*k^2" --select "k > 3 and k < 14"

Save table

Exports one table file per resolved path. Inside each table, first column is the selected axis expression, and additional columns are one data series per page.

save table --path <path-template> --axis <axis-expr> --column <data-expr> [options]

Options

Option Description
--path <path-template>
-p <path-template>		 Output path template (required). Pages resolving to the same path are grouped in one table.
--axis <expr>
-a <expr>		 Axis expression (required). Must be identical across grouped pages.
--column <expr>
-c <expr>		 Data expression (required). One output column per page.
--select <expr> Boolean expression used to filter rows before writing.
--domain <domain>
-d <domain>		 Domain used to resolve expressions. If omitted, inferred from axis expression.

Behavior

  • Pages with the same resolved --path are merged into one output table.
  • Column names are page names.
  • If axis arrays differ between grouped pages, EstraPy raises an error (Axis data mismatch ...).
  • Header includes axis/column expressions and list of original files.

Example 

save table --path "tables/chi_vs_k.dat" --axis k --column chi --domain reciprocal

save table --path "tables/chi_k2.dat" --axis k --column k^2*chi --select 2<=k<=14

Path Templates

--path supports metadata placeholders (template replacement), for example:

  • {.fn} → original file name
  • {sample} → metadata field named sample
  • {.f}_{.g} → generated page name and group ID

Example:

save columns --path "out/{sample}_{.fn}_norm.dat" --columns E mu

Notes and Best Practices

  • Use explicit expressions in --columns, --axis, and --column to make exported files self-documenting.
  • For save table, align data first (cut, interpolate, or rebin) to avoid axis mismatch errors.
  • Use --select to export only the physically relevant interval (e.g. EXAFS region).
  • Exports are plain text with fixed-width numeric formatting.

See Also