Tab-delimited output-format description
Overview: | |
The principal machine-readable data format supported by the USGS
Water Data for the Nation site is a
variant of a tab-delimited ASCII file structure called "rdb". The
rdb file structure consists of a header section containing zero or
more comment lines. The rdb header contains important information
such as disclaimers, sites, parameter and location names. The
header is followed by exactly one tab-delimited column-name row,
which is followed by exactly one column-definition row, and a data
section consisting of any number of rows of tab-delimited data
fields. The header comment lines start with a sharp sign (#)
followed by a space character followed by any text desired. The
fields in the tab-delimited column-name row contain the names of
each column. The fields in the tab-delimited column-definition row
contain the data definitions and optional column documentation for
each column. Data rows must have exactly the same number of
tab-delimited columns as both the column-name and column-definition
rows. Null data values are allowed. Example rdb file:
# ------------------------------------------- # Documentation lines. These describe and # identify the rdb file contents. # ------------------------------------------- NAME COUNT TYP AMT OTHER RIGHT 6s 5n 3s 5n 8s 8s Bill 44 A 133 Another This John 44 23 One Is Gary 77 77 Here On Mar 77 B 244 And The Greg 77 D 1111 So RightWhen reading (parsing) these rdb files, it is important to first parse the column-name row (the first non-comment row in the file) to determine the column position of each data value as different sites may return data columns in a different order. Information detailing the column-name syntax of the data file is contained in the header comments of the file for each data type. |
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Water Data for the Nation output-file format: | |
Tab-delimited data files output by the Water Data for the Nation site consist of tab-separated
columns of data for one or more sites. Each site is separated by a
header section of comments and new column definitions. The
following 3 column definitions are always included for each site:
Column Definition ---------- ----------------------------------------- agency_cd Agency collecting data or maintaining the site site_no USGS site-identification number datetime Date (and time for real-time data) in ISO formatThe remaining pairs of columns vary for each site depending on whether real-time or daily data are being output and on which data parameters were selected. For real-time data the data-column pairs use the format 'nn_nnnnn' 'nn_nnnnn_cd' where the first two-number sequence in each column name uniquely defines the sensor (the 'data descriptor') used to collect the data and the following five-number sequence defines the 'parameter_cd' which describes the type of data shown in the column. The second 'nn_nnnnn_cd' column in the pair contains data-value qualification codes pertaining specifically to the preceeding column. For daily data the data-column pairs use a similar format of 'nn_nnnnn_nnnnn' 'nn_nnnnn_nnnnn_cd' where the first two-number sequence in each column name uniquely defines the sensor (the 'data descriptor') used to collect the data, the next five-number sequence defines the 'parameter_cd' which describes the type of data shown in the column, and the next five-number sequence describes the type of daily statistic used to calculate the daily data value. The second 'nn_nnnnn_nnnnn_cd' column of the pair contains data-value qualification codes pertaining specifically to the preceeding column. A list of specific parameter codes, statistic codes (if daily data), and data-value qualification codes (if present) are included in the header for each site. For example: # Data for the following station(s) are contained in this file # ------------------------------------------------------------- # USGS 06041000 Madison River bl Ennis Lake nr McAllister MT # # Available data at this site--lines with asterisk '*' are included in this output. # DD parameter statistic - Description # -- ----- ----- ------------------------------------ # *02 00065 00003 - Gage height, feet (Mean) # *05 00010 00001 - Temperature, water, degrees Celsius (Maximum) # *05 00010 00002 - Temperature, water, degrees Celsius (Minimum) # *05 00010 00003 - Temperature, water, degrees Celsius (Mean) # *06 00060 00003 - Discharge, cubic feet per second (Mean) # # Data-value qualification codes included in this output: # A Approved for publication -- Processing and review completed. # P Provisional data subject to revision. # e Value has been estimated. |
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