Affymetrix® BAR Data File Format
BAR FILE
Description
The BAR file contains one and two sample analysis results (signal and p-values) from the tiling array software.
Format
The format of the BAR file is a binary file with data stored in big-endian format. The format of the file is a header section followed by sequences sections (one section per sequence defined).
Section Definitions
File Header
| Item | Description | Type | Size |
|---|---|---|---|
| 1 | Magic number. A value to identify the file type. The value is set to "barr\r\n\032\n�. | char | 8 bytes |
| 2 | The version number of the file. The version number is either 1.0 or 2.0. | float | 4 bytes |
| 3 | Number of sequences stored in the file. This will be referred to as NSEQ. | integer | 4 bytes |
| 4 | Number of columns per data point. This will be referred to as NCOL. | integer | 4 bytes |
| 5 | The field
types, one per column of data. The possible values are:
Currently only types 1 and 2 are used in Affymetrix BAR files. | integer | 4*NCOL |
| 6 | The number of
parameter name/value pairs. The parameter names and values are stored as
strings. Note: Items 7-10 are repeated for each parameter. | integer | 4 bytes |
| 7 | The length of the parameter name. | integer | 4 bytes |
| 8 | The parameter name. | char | Specified by item #7. |
| 9 | The length of the parameter value. | integer | 4 bytes |
| 10 | The parameter value. | char | Specified by item #9. |
Sequence
| Item | Description | Type | Size |
|---|---|---|---|
| 1 | The length of the sequence name. Referred to as SEQNAMELEN. | integer | 4 bytes |
| 2 | The sequence name. | char | Specified by item #1 |
| 3 | The length of the sequence group name. (only for version 2.0 and above files). | integer | 4 bytes |
| 4 | The name of the group which the sequence is a member (for example, often specifies organism). (only for version 2.0 and above files). | char | Specified by item #3 |
| 5 | The length of the sequence version. | integer | 4 bytes |
| 6 | The sequence version. | char | Specified by item #5 |
| 7 | The number of
parameter name/value pairs. (only for version 2.0 and above files). Note: Items 8-11 are repeated for each parameter. | integer | 4 bytes |
| 8 | The length of the parameter name. (only for version 2.0 and above files). | integer | 4 bytes |
| 9 | The name of the parameter. (only for version 2.0 and above files). | char | Specified by item #8 |
| 10 | The length of the parameter value. (only for version 2.0 and above files). | integer | 4 bytes |
| 11 | The value of the parameter. (only for version 2.0 and above files). | char | Specified by item #10 |
| 12 | The number of data points defined in the sequence. Each data point will contain NCOL column values. | integer | 4 bytes |
| 13 | The next set of values in the file is the data points for the sequence. Each data point contains NCOL column values. The type, thus the size, of each column is defined above in the field types section. | see description. | see description. |