StationXML

Read and write FDSN StationXML-format files describing seismic stations.

The package follows the FDSN schema.

import Pkg; Pkg.pkg"add https://github.com/anowacki/StationXML.jl"

StationXML is mainly designed to be used by other modules such as Seis to process station information. Therefore, relatively few convenience functions are defined for working with FDSNStationXML objects. However, the package aims to comprehensively document all objects and functions used.

The basic type exported by StationXML.jl is FDSNStationXML.

Two unexported functions are available for use in creating FDSNStationXML objects:

• StationXML.read(filename): Read from a file on disk.
• StationXML.readstring(string): Parse from a String.

For instance (using an example StationXML file supplied with this module):

julia> using StationXML

julia> sxml = StationXML.read(joinpath(dirname(pathof(StationXML)), "..", "test", data", "JSA.xml"))
StationXML.FDSNStationXML
  source: String "IRIS-DMC"
  sender: String "IRIS-DMC"
  module_name: String "IRIS WEB SERVICE: fdsnws-station | version: 1.1.36"
  module_uri: String "http://service.iris.edu/fdsnws/station/1/query?network=GB&station=JSA&level=response&format=xml&nodata=204"
  created: Dates.DateTime
  network: Array{StationXML.Network}((1,))
  schema_version: String "1.0"

Simply call write on an FDSNStationXML object to write it to disk or other IO stream:

julia> write("output_file.xml", sxml)

StationXML.jl always writes files according to the v1.1 schema.

Note that v1.1 removed a small number of fields from the specification. Therefore, if you are writing an FDSNStationXML object read from a v1.0 file, there is the potential that information may be lost. If you are worried, pass the warn=true keyword argument to write to enable warnings for the presence of any fields which will not be written.

You should access the fields of FDSNStationXML objects directly. These match the StationXML specification directly, and are listed in each type's docstrings. These are accessible via the REPL by typing ? and then the name of the type. For example:

julia> ? # REPL prompt becomes help?>
help> StationXML.Channel
  Channel

  A channel is a time series recording of a component of some observable, often
  colocated with other channels at the same location of a station.

  Equivalent to SEED blockette 52 and parent element for the related the response
  blockettes.

  │ Note
  │
  │  The presence of a sample_rate_ratio without a sample_rate field is not
  │  allowed in the standard, but it permitted by StationXML.jl.

  List of fields
  ≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡≡

    •    description::Union{Missing, String}
      
        Default: missing
...

To find out how many stations are in each of the networks returned in your request XML, and what the network code is, you can do:

julia> for net in sxml.network
           println(net.code, ": ", net.total_number_stations, " stations")
       end
BG: 29 stations

To get a vector of the station codes in the one network (GB) returned in our request:

julia> gb = sxml.network[1];

julia> stas = [sta.code for sta in gb.station]
1-element Array{String,1}:
 "JSA"

You can also access individual networks, stations and channels using functions with these names. For example, using the SeisRequests package to get all the broadband, high-gain channels stations in the GB network from 2012 to now:

julia> using StationXML, SeisRequests, Dates

julia> sxml = get_request(
                 FDSNStation(starttime=DateTime(2012), network="GB",
                             location="--", channel="BH?",
                             level="channel")).body |> String |>
                 StationXML.readstring;

julia> [s.code for s in stations(sxml)]
28-element Array{String,1}:
 "BIGH"
 "CCA1"
 "CLGH"
 "CWF"
 "DRUM"
 "DYA"
 "EDI"
 "EDMD"
 "ELSH"
 "ESK"
 "FOEL"
 "GAL1"
 "HMNX"
 "HPK"
 "HTL"
 "IOMK"
 "JSA"
 "KESW"
 "KPL"
 "LBWR"
 "LMK"
 "LRW"
 "MCH1"
 "SOFL"
 "STNC"
 "SWN1"
 "WACR"
 "WLF1"

You can easily construct vectors of all the networks, stations and channels in the StationXML using the following accessor functions:

• networks(stationxml)
• stations(stationxml_or_network)
• channels(stationxml_or_network_or_station)

Note that station, for instance, accepts either a Network or a whole FDSNStationXML object, whilst either of those or a Station can be given to channels.

julia> stations(gb)
28-element Array{StationXML.Station,1}:
 StationXML.Station(missing, StationXML.Comment[], "BIGH", 2009-12-15T00:00:00, 2599-12-31T23:59:59, StationXML.RestrictedStatus
  value: String "open"
...

The channel_codes function returns a list of all of the channel codes within a FDSNStationXML document or a Network.

The module defines getproperty methods for conveniently accessing the fields of each member of arrays of Networks, Stations and Channels. So our previous example of finding all the station codes could actually have been done like this:

julia> stations(sxml).code
28-element Array{String,1}:
 "BIGH"
 "CCA1"
 "CLGH"
 "CWF"
...

We can equally access any other field of the items this way:

julia> channels(sxml).longitude
84-element Array{Float64,1}:
 StationXML.Longitude(-3.9087, missing, missing, missing, "WGS84")
 StationXML.Longitude(-3.9087, missing, missing, missing, "WGS84")
 StationXML.Longitude(-3.9087, missing, missing, missing, "WGS84")
 StationXML.Longitude(-5.227299, missing, missing, missing, "WGS84")
 StationXML.Longitude(-5.227299, missing, missing, missing, "WGS84")
 StationXML.Longitude(-5.227299, missing, missing, missing, "WGS84")
 StationXML.Longitude(-6.110599, missing, missing, missing, "WGS84")
 StationXML.Longitude(-6.110599, missing, missing, missing, "WGS84")
 StationXML.Longitude(-6.110599, missing, missing, missing, "WGS84")
 ⋮

You can merge together mulitiple FDSNStationXML objects with merge (returining a copy and not modifying the originals), or merge!, which updates the first object given. In situations where it is obvious that two networks, stations or channels are the same, these will not be duplicated in the final merged object. Cases which are ambiguous are not merged and the user is warned by default.

As an alternative to merge!, one can simply append! two objects together. This simply has the effect of copying everything in one FDSNStationXML object into another, and duplication is not avoided.

StationXML represents the XML as laid out in the StationXML schema. Therefore, it contains all the information in a StationXML file which is part of the StationXML standard. Elements and attributes of the XML are fields within structures nested several layers deep.

StationXML.jl should read any schema-compatible StationXML file without error, therefore any examples of documents failing are very warmly welcomed as are all bug reports.

Please open an issue with a link to the document which is causing problems and as much information as possible about how to reproduce your error.

If you would like to add a feature to StationXML, this will be seriously considered. The package aims to be fairly minimal so please think very carefully before adding large dependencies.

New code for the repo should come via a pull request.