quickstart.rst

Quickstart

pystac-client can be used as either a Command Line Interface (CLI) or a Python library.

CLI

Use the CLI to quickly make searches and output or save the results.

The --matched switch performs a search with limit=1 so does not get any Items, but gets the total number of matches which will be output to the screen (if supported by the STAC API).

$ stac-client search https://earth-search.aws.element84.com/v0 -c sentinel-s2-l2a-cogs --bbox -72.5 40.5 -72 41 --matched
2179 items matched

If the same URL is to be used over and over, define an environment variable to be used in the CLI call:

$ export STAC_API_URL=https://earth-search.aws.element84.com/v0
$ stac-client search ${STAC_API_URL} -c sentinel-s2-l2a-cogs --bbox -72.5 40.5 -72 41 --datetime 2020-01-01/2020-01-31 --matched
48 items matched

Without the --matched switch, all items will be fetched, paginating if necessary. If the --max-items switch is provided it will stop paging once that many items has been retrieved. It then prints all items to stdout as an ItemCollection. This can be useful to pipe output to another process such as stac-terminal, geojsonio-cli, or jq.

$ stac-client search ${STAC_API_URL} -c sentinel-s2-l2a-cogs --bbox -72.5 40.5 -72 41 --datetime 2020-01-01/2020-01-31 | stacterm cal --label platform

If the --save switch is provided instead, the results will not be output to stdout, but instead will be saved to the specified file.

$ stac-client search ${STAC_API_URL} -c sentinel-s2-l2a-cogs --bbox -72.5 40.5 -72 41 --datetime 2020-01-01/2020-01-31 --save items.json

If the Catalog supports the Query extension, any Item property can also be included in the search. Rather than requiring the JSON syntax the Query extension uses, pystac-client uses a simpler syntax that it will translate to the JSON equivalent. Note however that when the simple syntax is used it sends all property values to the server as strings, except for gsd which it casts to float. This means that if there are extensions in use with numeric properties these will be sent as strings. Some servers may automatically cast this to the appropriate data type, others may not.

The query filter will also accept complete JSON as per the specification.

<property><operator><value>

where operator is one of `>=`, `<=`, `>`, `<`, `=`

Examples:
eo:cloud_cover<10
created=2021-01-06
view:sun_elevation<20

Any number of properties can be included, and each can be included more than once to use additional operators.

$ stac-client search ${STAC_API_URL} -c sentinel-s2-l2a-cogs --bbox -72.5 40.5 -72 41 --datetime 2020-01-01/2020-01-31 -q "eo:cloud_cover<10" --matched
10 items matched

$ stac-client search ${STAC_API_URL} -c sentinel-s2-l2a-cogs --bbox -72.5 40.5 -72 41 --datetime 2020-01-01/2020-01-31 -q "eo:cloud_cover<10" "eo:cloud_cover>5" --matched
4 items matched

Python

To use the Python library, first a Client instance is created for a specific STAC API (use the root URL):

from pystac_client import Client

catalog_client = Client.open("https://earth-search.aws.element84.com/v0")

Create a search:

my_search = catalog_client.search(collections=['sentinel-s2-l2a-cogs'], bbox=[-72.5,40.5,-72,41], max_items=10)
print(f"{mysearch.matched()} items found")

The items() generator method can be used to iterate through all resulting items.

for item in my_search.items():
    print(item.id)

To convert all of Items from a search as a single PySTAC ItemCollection, you must first do a limited iteration on the iterator to get a list of Items, and then create an ItemCollection with that. The ItemCollection can then be saved as a GeoJSON FeatureCollection.

Save all found items as a single FeatureCollection:

from pystac import ItemCollection

my_itemcollection = ItemCollection(items = list(my_search.items()))
my_itemcollection.save_object('my_itemcollection.json')