# Matching filtered Vector{String} to non-filtered Matrix{Any} - GPS station names

**URL:** <https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230>\
**Category:** New to Julia\
**Tags:** question, indexing, matrices, geodatascience, geodesy\
**Created:** [February 15, 2024, 3:21am UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230 "2024-02-15T03:21:54Z")\
**Posts on this page:** 10\
**Page:** 1

<div class="post-metadata">

**Author:** ![GeodeticR](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/geodeticr/32/218661_2.png) [@GeodeticR](https://discourse.julialang.org/u/GeodeticR)\
**Post date:** [February 15, 2024, 3:21am UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/1 "2024-02-15T03:21:54Z")

</div>

Hello all,

I’ve been attempting to match an array of GPS stations names that I’ve filtered such that I have a time frame I’m interested and that the percentage of collection in that time is \> 93%.

The issue is, that I have a non-filtered Matrix containing all the GPS station names, longitudes, and latitudes.

Here is the overall code that I’ve implemented:

```julia
using HTTP, DelimitedFiles

midas = readdlm("midas.NA.txt")

filter1 = (midas[:,3] .<= 2001.5000) .& (midas[:,4] .>= 2006.0000)
lon_lat = midas[:, [1, 26, 25]]
midasfilter1 = midas[filter1, :]

writedlm("Stats1.txt", midasfilter1[:,1]) 

#2

function empty_set(url)
	try
		time_series = HTTP.get(url)
		
		stringy = String(time_series.body)
		
		linefilter = length(split(stringy, "\n"))
		
		return linefilter < 1700 
		
		catch e
			return true
	end
end

stats2_names = readdlm("Stats1.txt", String)

IGS14_url = "http://geodesy.unr.edu/gps_timeseries/tenv3/IGS14/"

midas_bytes = String[]

for station in stats2_names 

	station = strip(station)
	
	url1 = IGS14_url * "$station.tenv3"
	
	if !empty_set(url1)
		push!(midas_bytes, station)
	end
end

```

I’m still very new to Julia and this type of analysis (which I really haven’t even gotten to yet), but the non-filtered Matrix is here:

```julia
lon_lat
8749×3 Matrix{Any}:
 "1LSU" -91.1803 30.4074
 "1NSU" -93.0976 31.7508
 "1ULM" -92.0759 32.529
 "299C" -142.076 64.0289
 "3RIV" -72.5761 46.3148
 "59WE" -112.183 33.4311
 "5PTS" -120.265 36.4292
 "7OAK" -114.759 37.595
 "7ODM" -117.093 34.1164

```

and the filtered stations that I need to match the longitude and latitudes of are here:

```julia
midas_bytes
650-element Vector{String}:
 "7ODM"
 "AGMT"
 "AHID"
 "AIS5"
 "AIS6"
 "ALAM"
 "ALBH"

```

All I want to do is create a new matrix that has the matched midas\_bytes elements with their appropriate longitude and latitude from the lon\_lat and write that as a text file that I can then plot.

In terms of steps I’ve taken to try and match the station names, I’ve done the following to make sure that the first column of each are actually outputting the stations names, which they are:

```julia
for (i,stations) in enumerate(lon_lat[:, 1])
           println("station $i: $stations")
               if i >= 100
               break
           end
       end
station 1: 1LSU
station 2: 1NSU
station 3: 1ULM
station 4: 299C
station 5: 3RIV
station 6: 59WE
station 7: 5PTS
station 8: 7OAK
station 9: 7ODM

```

and:

```julia
for (i,stations) in enumerate(midas_bytes)
    println("station $i: $stations")
        if i >= 100
        break
    end
end
station 1: 7ODM
station 2: AGMT
station 3: AHID
station 4: AIS5
station 5: AIS6
station 6: ALAM
station 7: ALBH
station 8: ALGO
station 9: AMC2
station 10: ANP5

```

Which, at least to me means they should be matching if I create some comparison between the two data sets?

But when I tried to implement the following potential solution I found on this site:

```julia
ll_f = filter(x -> x[1] in midas_bytes, lon_lat)

```

I would get the following:

```julia
Any[]

```

I tried various iterations of that same filter that included SplitApplyCombine, eachcol(), Base.Iterators and whatever other suggestion I found both on this site, and ChatGPT.

I’m sure there is some simple process that I’m just too green to come up with. But I’m at my wits end and have been banging my head against the wall for the last 2-days just trying to figure what, what I originally thought would be a quick step, other things I could do to get a new text file that has the filtered midas\_bytes list with their corresponding lons and lats.

Any insight would be greatly appreciated. Thank you! I’ve attached the Julia code with all my notes with it in case it would be helpful to see my though process behind my work flow.

[gps\_iterate.jl](https://discourse.julialang.org/uploads/short-url/xVFmyZeE6TqHGawZmBcbIe2HAvc.jl) (3.8 KB)

The text file from the beginning of the script is here: [midas.NA.txt](http://geodesy.unr.edu/velocities/midas.NA.txt)

- A grateful first year grad student. 🫠

---

<div class="post-metadata">

**Author:** ![nilshg](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nilshg/32/2283_2.png) [@nilshg](https://discourse.julialang.org/u/nilshg)\
**Post date:** [February 15, 2024, 10:14am UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/2 "2024-02-15T10:14:16Z")

</div>

I might misunderstand but aren’t you just trying a `leftjoin` here? There are more lightweight options available but the simplest is probably just to use a standard `DataFrames` workflow:

```julia
julia> using DataFrames

julia> lldf = DataFrame(lon_lat, [:station, :lon, :lat])
9×3 DataFrame
 Row │ station lon lat
     │ Any Any Any
─────┼────────────────────────────
   1 │ 1LSU -91.1803 30.4074
   2 │ 1NSU -93.0976 31.7508
   3 │ 1ULM -92.0759 32.529
   4 │ 299C -142.076 64.0289
   5 │ 3RIV -72.5761 46.3148
   6 │ 59WE -112.183 33.4311
   7 │ 5PTS -120.265 36.4292
   8 │ 7OAK -114.759 37.595
   9 │ 7ODM -117.093 34.1164

julia> mdf = DataFrame(station = midas_bytes);

julia> leftjoin(mdf, lldf, on = :station)
7×3 DataFrame
 Row │ station lon lat
     │ String Any Any
─────┼────────────────────────────
   1 │ 7ODM -117.093 34.1164
   2 │ AGMT missing missing
   3 │ AHID missing missing
   4 │ AIS5 missing missing
   5 │ AIS6 missing missing
   6 │ ALAM missing missing
   7 │ ALBH missing missing

```

---

<div class="post-metadata">

**Author:** ![GeodeticR](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/geodeticr/32/218661_2.png) [@GeodeticR](https://discourse.julialang.org/u/GeodeticR)\
**Post date:** [February 15, 2024, 4:35pm UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/3 "2024-02-15T16:35:37Z")

</div>

Man, can’t believe I didn’t stumble across somethingike this earlier! Or maybe I did and glanced right over it.

Once I join the the two, would I be able to apply a similar process that I did above to get rid of the “missing” station names? Otherwise I’m going to have around 8000 lines of no use. Lol

Thank you!

---

<div class="post-metadata">

**Author:** ![Jeff\_Emanuel](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jeff_emanuel/32/15440_2.png) [@Jeff\_Emanuel](https://discourse.julialang.org/u/Jeff_Emanuel)\
**Post date:** [February 15, 2024, 5:07pm UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/5 "2024-02-15T17:07:35Z")

</div>

[https://dataframes.juliadata.org/stable/lib/functions/#Base.filter](https://dataframes.juliadata.org/stable/lib/functions/#Base.filter)

---

<div class="post-metadata">

**Author:** ![GeodeticR](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/geodeticr/32/218661_2.png) [@GeodeticR](https://discourse.julialang.org/u/GeodeticR)\
**Post date:** [February 15, 2024, 5:18pm UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/6 "2024-02-15T17:18:58Z")

</div>

Thank you much! I knew it would be something simple.

---

<div class="post-metadata">

**Author:** ![simsurace](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/simsurace/32/30216_2.png) [@simsurace](https://discourse.julialang.org/u/simsurace)\
**Post date:** [February 15, 2024, 5:31pm UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/7 "2024-02-15T17:31:00Z")

</div>

There is also `dropmissing`

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<div class="post-metadata">

**Author:** ![GeodeticR](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/geodeticr/32/218661_2.png) [@GeodeticR](https://discourse.julialang.org/u/GeodeticR)\
**Post date:** [February 15, 2024, 6:22pm UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/8 "2024-02-15T18:22:49Z")

</div>

Thank you! Lots of things to add to my repertoire. I really appreciate the helpfulness of the community.

---

<div class="post-metadata">

**Author:** ![GeodeticR](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/geodeticr/32/218661_2.png) [@GeodeticR](https://discourse.julialang.org/u/GeodeticR)\
**Post date:** [February 15, 2024, 6:51pm UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/9 "2024-02-15T18:51:46Z")

</div>

Nevermind! Looks like once I applied the left join it automatically omitted the “missing” lines here. I hate how straightforward that is, and yet, I was not clever enough to find it on my own! Thank you again. You saved me. lol

```julia
leftjoin(gps_df, lldf, on = :station)
650×3 DataFrame
 Row │ station lon lat
     │ String Any Any
─────┼────────────────────────────
   1 │ 7ODM -117.093 34.1164
   2 │ AGMT -116.429 34.5943
   3 │ AHID -111.064 42.7731
   4 │ AIS5 -131.6 55.0691
   5 │ AIS6 -131.599 55.0689
   6 │ ALAM -115.158 37.358
   7 │ ALBH -123.487 48.3898
   8 │ ALGO -78.0714 45.9558
   9 │ AMC2 -104.525 38.8031

```

---

<div class="post-metadata">

**Author:** ![Jeff\_Emanuel](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/jeff_emanuel/32/15440_2.png) [@Jeff\_Emanuel](https://discourse.julialang.org/u/Jeff_Emanuel)\
**Post date:** [February 15, 2024, 6:56pm UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/10 "2024-02-15T18:56:53Z")

</div>

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---

<div class="post-metadata">

**Author:** ![GeodeticR](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/geodeticr/32/218661_2.png) [@GeodeticR](https://discourse.julialang.org/u/GeodeticR)\
**Post date:** [February 15, 2024, 7:44pm UTC](https://discourse.julialang.org/t/matching-filtered-vector-string-to-non-filtered-matrix-any-gps-station-names/110230/11 "2024-02-15T19:44:51Z")

</div>

Awesome, and it is available at my university library. Appreciate the recommendation!