Is there a function to inverse the ST_MAKEPOLYGON and get a linestring from a polygon?
The best option I have found so far is to modify the geometry at the WKB level.
with data AS (
SELECT ST_MAKEPOLYGON(ST_MAKELINE([
ST_GEOGPOINT(7.48,6.74),
ST_GEOGPOINT(7.50,6.73),
ST_GEOGPOINT(7.47,6.76),
ST_GEOGPOINT(7.48,6.74)
])) AS my_polygon
)
SELECT
ST_GEOGFROMWKB(CONCAT(b'\x01\x02',SUBSTR(ST_ASBINARY(my_polygon),7)))
FROM data
Try below
SELECT ST_EXTERIORRING(my_polygon)
If applied to sample data in your question - output is
Related
I'm working on building a follow-network form Github's available data on Google BigQuery, e.g.: https://bigquery.cloud.google.com/table/githubarchive:day.20210606
The key data is contained in the "payload" field, STRING type. I managed to unnest the data contained in that field and convert it to an array, but how can I get the last element?
Here is what I have so far...
select type,
array(select trim(val) from unnest(split(trim(payload, '[]'))) val) payload
from `githubarchive.day.20210606`
where type = 'MemberEvent'
Which outputs:
How can I get only the last element, "Action":"added"} ?
I know that
select array_reverse(your_array)[offset(0)]
should do the trick, however I'm unsure how to combine that in my code. I've been trying different options without success, for example:
with payload as ( select array(select trim(val) from unnest(split(trim(payload, '[]'))) val) payload from `githubarchive.day.20210606`)
select type, ARRAY_REVERSE(payload)[ORDINAL(1)]
from `githubarchive.day.20210606` where type = 'MemberEvent'
The desired output should look like:
To get last element in array you can use below approach
select array_reverse(your_array)[offset(0)]
I'm unsure how to combine that in my code
select type, array_reverse(array(
select trim(val)
from unnest(split(trim(payload, '[]'))) val
))[offset(0)]
from `githubarchive.day.20210606`
where type = 'MemberEvent'
There is a solution without reversing the array.
SELECT event[OFFSET(ARRAY_LENGTH(event)-1)
I am trying to flatten inside_array or sub array of nested array data into table rows.
I am able to flatten array_data which is outside array.
Anybody have any suggestion.Thanks in advance
#standardSQL
SELECT ...
FROM `project.dataset.table`,
UNNEST(array_data) AS array_data_rec,
UNNEST(array_data_rec.inside_array) AS inside_array_rec
To handle "no data inside the inside_array" - use LEFT JOIN instead as in below example
#standardSQL
SELECT ...
FROM `project.dataset.table`,
UNNEST(array_data) AS array_data_rec
LEFT JOIN UNNEST(array_data_rec.inside_array) AS inside_array_rec
You can do following
...
FROM
AA.nested_array,
UNNEST(array_data) as array_data,
UNNEST(array_data.inside_array) as array_data_inside_array
Does anybody know what is the problem with my query. I am trying to calculate area using geographical coordinates, but result seems to be too small to be true. 0.00118 sqm. Can anybody help?
SELECT ST_Area(the_geom) As sqm
FROM (SELECT
ST_GeomFromText('POLYGON
(
(14.604514925547997 121.0968017578125,
14.595212295624522 121.08512878417969,
14.567302046916149 121.124267578125,
14.596541266841905 121.14761352539062,
14.604514925547997 121.0968017578125)
)',4326) ) As foo(the_geom)
How accurate should be the calculation?
A solution is to cast GEOMETRY to GEOGRAPHY, which is acceptably accurate for the most use cases:
SELECT ST_Area(the_geom::GEOGRAPHY ) As sqm
FROM (SELECT
ST_GeomFromText('POLYGON
(
(14.604514925547997 121.0968017578125,
14.595212295624522 121.08512878417969,
14.567302046916149 121.124267578125,
14.596541266841905 121.14761352539062,
14.604514925547997 121.0968017578125)
)',4326) ) As foo(the_geom)
The geography type automatically converts degrees to meters.
Depending on your scenario you could also use directly the geography constructor St_GeographyFromText, which accept a WKT string as argument, very similar to ST_GeomFromText
ST_GeographyFromText('POLYGON((14.604514925547997 121.0968017578125,
14.595212295624522 121.08512878417969,
14.567302046916149 121.124267578125,
14.596541266841905 121.14761352539062,
14.604514925547997 121.0968017578125))'
)
I have the following sample data and I am trying to explode it in hive.. I used split but I know I am missing something..
["[[-80.742426,35.23248],[-80.740424,35.23184],[-80.739583,35.231562],[-80.735935,35.23041],[-80.728624,35.228069],[-80.727753,35.227836],[-80.727294,35.227741],[-80.726762,35.227647],[-80.726321,35.227594],[-80.725687,35.227544],[-80.725134,35.227535],[-80.721502,35.227615],[-80.691298,35.216202],[-80.688009,35.215396],[-80.686516,35.215016],[-80.598433,35.234307]]"]
I used the below query
select explode(split(col, ',')) from sample2;
and the result is this
["[[-80.742426
35.23248]
[-80.740424
35.23184]
[-80.739583
35.231562]
[-80.735935
35.23041]
[-80.728624
35.228069]
[-80.727753
35.227836]
[-80.71143
35.227831]
[-80.711007
35.227795]
[-80.710638
35.227741]
[-80.673884
35.21014]
[-80.672358
35.209481]
[-80.672036
35.209356]
[-80.671686
35.209234]
[-80.67124
35.209099]
[-80.670815
35.209006]
[-80.670267
35.208906]
[-80.669612
35.208833]
[-80.668924
35.208806]
[-80.598433
35.234307]]"]
I need it in below format
[-80.742426,35.23248]
[-80.740424,35.23184]
[-80.739583,35.231562]
[-80.735935,35.23041]
[-80.728624,35.228069]
[-80.727753,35.227836]
[-80.727294,35.227741]
[-80.726762,35.227647]
[-80.726321,35.227594]
[-80.725687,35.227544]
[-80.725134,35.227535]
[-80.721502,35.227615]
[-80.691298,35.216202]
[-80.688009,35.215396]
[-80.686516,35.215016]
[-80.684281,35.214466]
[-80.68396,35.214395]
[-80.683375,35.214231]
[-80.682908,35.214079]
[-80.682444,35.213905]
[-80.682045,35.213733]
[-80.68062,35.213112]
[-80.678078,35.211983]
[-80.676836,35.211447]
[-80.598433,35.234307]
Any help over here..?
You have your data set as arrays of array and you want to explode your data at first level only, so use LATERAL VIEW explode(colname) to explode at the first level.
Below is the SELECT query with explode():
SELECT col1 FROM sample2 LATERAL VIEW EXPLODE(col) explodeVal AS col1;
output generated from your input data set as below:
[-80.742426,35.23248]
[-80.740424,35.23184]
[-80.739583,35.231562]
[-80.735935,35.23041]
[-80.728624,35.228069]
[-80.727753,35.227836]
[-80.727294,35.227741]
[-80.726762,35.227647]
[-80.726321,35.227594]
[-80.725687,35.227544]
[-80.725134,35.227535]
[-80.721502,35.227615]
[-80.691298,35.216202]
[-80.688009,35.215396]
[-80.686516,35.215016]
[-80.684281,35.214466]
[-80.68396,35.214395]
[-80.683375,35.214231]
[-80.682908,35.214079]
[-80.682444,35.213905]
[-80.682045,35.213733]
[-80.68062,35.213112]
[-80.678078,35.211983]
[-80.676836,35.211447]
[-80.598433,35.234307]
Is there an easy way to do URL decoding within the BigQuery query language? I'm working with a table that has a column containing URL-encoded strings in some values. For example:
http://xyz.com/example.php?url=http%3A%2F%2Fwww.example.com%2Fhello%3Fv%3D12345&foo=bar&abc=xyz
I extract the "url" parameter like so:
SELECT REGEXP_EXTRACT(column_name, "url=([^&]+)") as url
from [mydataset.mytable]
which gives me:
http%3A%2F%2Fwww.example.com%2Fhello%3Fv%3D12345
What I would like to do is something like:
SELECT URL_DECODE(REGEXP_EXTRACT(column_name, "url=([^&]+)")) as url
from [mydataset.mytable]
thereby returning:
http://www.example.com/hello?v=12345
I would like to avoid using multiple REGEXP_REPLACE() statements (replacing %20, %3A, etc...) if possible.
Ideas?
Below is built on top of #sigpwned answer, but slightly refactored and wrapped with SQL UDF (which has no limitation that JS UDF has so safe to use)
#standardSQL
CREATE TEMP FUNCTION URLDECODE(url STRING) AS ((
SELECT SAFE_CONVERT_BYTES_TO_STRING(
ARRAY_TO_STRING(ARRAY_AGG(
IF(STARTS_WITH(y, '%'), FROM_HEX(SUBSTR(y, 2)), CAST(y AS BYTES)) ORDER BY i
), b''))
FROM UNNEST(REGEXP_EXTRACT_ALL(url, r"%[0-9a-fA-F]{2}|[^%]+")) AS y WITH OFFSET AS i
));
SELECT
column_name,
URLDECODE(REGEXP_EXTRACT(column_name, "url=([^&]+)")) AS url
FROM `project.dataset.table`
can be tested with example from question as below
#standardSQL
CREATE TEMP FUNCTION URLDECODE(url STRING) AS ((
SELECT SAFE_CONVERT_BYTES_TO_STRING(
ARRAY_TO_STRING(ARRAY_AGG(
IF(STARTS_WITH(y, '%'), FROM_HEX(SUBSTR(y, 2)), CAST(y AS BYTES)) ORDER BY i
), b''))
FROM UNNEST(REGEXP_EXTRACT_ALL(url, r"%[0-9a-fA-F]{2}|[^%]+")) AS y WITH OFFSET AS i
));
WITH `project.dataset.table` AS (
SELECT 'http://example.com/example.php?url=http%3A%2F%2Fwww.example.com%2Fhello%3Fv%3D12345&foo=bar&abc=xyz' column_name
)
SELECT
URLDECODE(REGEXP_EXTRACT(column_name, "url=([^&]+)")) AS url,
column_name
FROM `project.dataset.table`
with result
Row url column_name
1 http://www.example.com/hello?v=12345 http://example.com/example.php?url=http%3A%2F%2Fwww.example.com%2Fhello%3Fv%3D12345&foo=bar&abc=xyz
Update with further quite optimized SQL UDF
CREATE TEMP FUNCTION URLDECODE(url STRING) AS ((
SELECT STRING_AGG(
IF(REGEXP_CONTAINS(y, r'^%[0-9a-fA-F]{2}'),
SAFE_CONVERT_BYTES_TO_STRING(FROM_HEX(REPLACE(y, '%', ''))), y), ''
ORDER BY i
)
FROM UNNEST(REGEXP_EXTRACT_ALL(url, r"%[0-9a-fA-F]{2}(?:%[0-9a-fA-F]{2})*|[^%]+")) y
WITH OFFSET AS i
));
It's a good feature request, but currently there is no built in BigQuery function that provides URL decoding.
One more workaround is using a user-defined function.
#standardSQL
CREATE TEMPORARY FUNCTION URL_DECODE(enc STRING)
RETURNS STRING
LANGUAGE js AS """
try {
return decodeURI(enc);;
} catch (e) { return null }
return null;
""";
SELECT ven_session,
URL_DECODE(REGEXP_EXTRACT(para,r'&kw=(\w|[^&]*)')) AS q
FROM raas_system.weblog_20170327
WHERE para like '%&kw=%'
LIMIT 10
I agree with everyone here that URLDECODE should be a native function. However, until that happens, it is possible to write a "native" URLDECODE:
SELECT id, SAFE_CONVERT_BYTES_TO_STRING(ARRAY_TO_STRING(ps, b'')) FROM (SELECT
id,
ARRAY_AGG(CASE
WHEN REGEXP_CONTAINS(y, r"^%") THEN FROM_HEX(SUBSTR(y, 2))
ELSE CAST(y AS bytes)
END ORDER BY i) AS ps
FROM (SELECT x AS id, REGEXP_EXTRACT_ALL(x, r"%[0-9a-fA-F]{2}|[^%]+") AS element FROM UNNEST(ARRAY['domodossola%e2%80%93locarno railway', 'gabu%c5%82t%c3%b3w']) AS x) AS x
CROSS JOIN UNNEST(x.element) AS y WITH OFFSET AS i GROUP BY id);
In this example, I've tried and tested the implementation with a couple of percent-encoded page names from Wikipedia as the input. It should work with your input, too.
Obviously, this is extremely unwieldly! For that reason, I'd suggest building a materialized join table, or wrapping this in a view, rather than using this expression "naked" in your query. However, it does appear to get the job done, and it doesn't hit the UDF limits.
EDIT: #MikhailBerylyant's post below has wrapped this cumbersome implementation into a nice, tidy little SQL UDF. That's a much better way to handle this!