Allow --bbox to be a file containing four bounding-box coordinates

.gitignore

@@ -128,5 +128,12 @@ dmypy.json
 # Pyre type checker
 .pyre/
 
+# Strava data
+activities.csv
+activities/
+
+# Arbitrary extension for bounding box coordinates
+*.bbox
+
 # Generated files
 *.png

README.md

@@ -27,6 +27,36 @@ Then run from the terminal:
 stravavis --help
 ```
 
+## How to use
+
+If your activity data is in a folder called `activities`, run the following command:
+
+```sh
+stravavis activities
+```
+
+By default, this will create output images prefixed `strava-`.
+
+If you have an `activities.csv` file:
+
+```sh
+stravavis activities --activities_path activities.csv
+```
+
+To only map activities contained within a
+[bounding box](https://boundingbox.klokantech.com/):
+
+```sh
+stravavis activities --bbox 24.782802,59.922486,25.254511,60.29785`
+```
+
+Or as a shortcut, save bounding-box coordinates to a file:
+
+```sh
+echo 24.782802,59.922486,25.254511,60.29785 > helsinki.bbox
+stravavis activities --bbox helsinki.bbox
+```
+
 ## Examples
 
 ### Facets

src/stravavis/cli.py

@@ -96,10 +96,19 @@ def main():
         sys.exit(f"No files found matching {args.path}")
 
     if args.bbox:
-        # Convert comma-separated string into floats
-        args.lon_min, args.lat_min, args.lon_max, args.lat_max = (
-            float(x) for x in args.bbox.split(",")
-        )
+        try:
+            bbox_values = args.bbox.split(",")
+            if len(bbox_values) == 1:
+                with open(args.bbox) as f:
+                    bbox_values = f.readline().split(",")
+            args.lon_min, args.lat_min, args.lon_max, args.lat_max = map(
+                float, bbox_values
+            )
+        except ValueError:
+            sys.exit(
+                f"Bounding box '{args.bbox}' must be four comma-separated coordinates "
+                "or a file containing them"
+            )
 
     if args.activities_path and os.path.isdir(args.activities_path):
         args.activities_path = os.path.join(args.activities_path, "activities.csv")