tensogram set

Modifies metadata keys in messages and writes the result to a new file. Matching messages are decoded, their metadata is updated, and they are re-encoded with the original payload bytes and pipeline settings.

Usage

tensogram set [OPTIONS] -s <SET_VALUES> <INPUT> <OUTPUT>

Options

Option	Description
`-s <SET_VALUES>`	Key=value pairs to set (comma-separated)
`-w <WHERE_CLAUSE>`	Only modify messages matching this filter (e.g. `mars.param=2t`)
`-h, --help`	Print help

Examples

# Change mars.date to 20260402 in all messages
tensogram set input.tgm output.tgm mars.date=20260402

# Set multiple keys at once
tensogram set input.tgm output.tgm mars.date=20260402,mars.step=12

# Only modify temperature fields
tensogram set input.tgm output.tgm mars.class=rd -w "mars.param=2t"

Key=Value Syntax

Multiple mutations can be specified as a comma-separated list:

tensogram set in.tgm out.tgm key1=val1,key2=val2,key3=val3

Keys use dot-notation: mars.param sets the param field inside the mars namespace. A top-level key like experiment sets a top-level metadata field.

Object-level metadata can be updated with objects.<index>.<path>:

# Add object-specific metadata to the first object
tensogram set input.tgm output.tgm objects.0.processing.version=2

Structural/Integrity Keys

The following keys cannot be modified because they describe the physical structure of the payload. Changing them would make the metadata inconsistent with the actual bytes on disk:

Key	Reason
`shape`	Tensor dimensions
`strides`	Memory layout
`dtype`	Element type
`ndim`	Number of dimensions
`type`	Object type
`encoding`	Encoding algorithm
`filter`	Filter algorithm
`compression`	Compression algorithm
`hash`	Payload integrity hash
`szip_rsi`	Szip compression block parameter
`szip_block_size`	Szip compression block parameter
`szip_flags`	Szip compression flags
`szip_block_offsets`	Szip block seek table
`sp_reference_value`	Simple packing quantization parameter
`sp_binary_scale_factor`	Simple packing quantization parameter
`sp_decimal_scale_factor`	Simple packing quantization parameter
`sp_bits_per_value`	Simple packing quantization parameter
`shuffle_element_size`	Shuffle filter parameter

Attempting to modify any of these returns an error before any output is written.

Pass-Through for Non-Matching Messages

Messages that do not match the -w filter are copied verbatim to the output file. Their bytes are not re-encoded or re-hashed.

Note: Messages that are modified are re-encoded after the metadata mutation. Because the decoded payload bytes are unchanged, set preserves the original payload hash instead of recomputing it.

Workflow

flowchart TD
    A[Read message] --> B{Matches -w?}
    B -- No --> C[Write raw bytes to output]
    B -- Yes --> D[Decode metadata]
    D --> E[Apply mutations]
    E --> F[Re-encode message\npreserve payload hash]
    F --> G[Write to output]
    C --> H[Next message]
    G --> H

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