Coverage for pyguymer3/osterrain/findExtent.py: 4%

1#!/usr/bin/env python3 

2 

3# Define function ... 

4def findExtent( 

5 fname0, 

6 /, 

7): 

8 """Find the extent of the dataset 

9 

10 Parameters 

11 ---------- 

12 fname0 : str 

13 the path to the dataset 

14 

15 Returns 

16 ------- 

17 minX : int 

18 the left edge 

19 maxX : int 

20 the right edge 

21 minY : int 

22 the bottom edge 

23 maxY : int 

24 the top edge 

25 

26 Notes 

27 ----- 

28 

29 Copyright 2017 Thomas Guymer [1]_ 

30 

31 References 

32 ---------- 

33 .. [1] PyGuymer3, https://github.com/Guymer/PyGuymer3 

34 """ 

35 

36 # Import standard modules ... 

37 import io 

38 import re 

39 import zipfile 

40 

41 # Import sub-functions ... 

42 from .loadASCIIheader import loadASCIIheader 

43 

44 # ************************************************************************** 

45 

46 # Initialize limits ... 

47 maxX = -2**31 

48 maxY = -2**31 

49 minX = 2**31 

50 minY = 2**31 

51 

52 # Compile regex to save time ... 

53 pattern = re.compile(r"data/[a-z]+/[a-z]+[0-9]+_OST50GRID_[0-9]+.zip") 

54 

55 # Load dataset ... 

56 with zipfile.ZipFile(fname0, "r") as fObj0: 

57 # Loop over members ... 

58 for fname1 in fObj0.namelist(): 

59 # Skip this member if it is not a sub-dataset ... 

60 if pattern.match(fname1) is None: 

61 continue 

62 

63 # Determine sub-dataset key ... 

64 key = fname1.split("/")[-1].split("_")[0].upper() 

65 

66 # Read sub-dataset into RAM so that it becomes seekable ... 

67 # NOTE: https://stackoverflow.com/a/12025492 

68 zipObj = io.BytesIO(fObj0.read(fname1)) 

69 

70 # Load sub-dataset ... 

71 with zipfile.ZipFile(zipObj, "r") as fObj1: 

72 # Read ASCII dataset into RAM so that it becomes seekable ... 

73 # NOTE: https://stackoverflow.com/a/12025492 

74 ascObj = io.BytesIO(fObj1.read(f"{key}.asc")) 

75 

76 # Load header of ASCII dataset ... 

77 hdr = loadASCIIheader(ascObj) 

78 

79 # Increment limits ... 

80 maxX = max(maxX, hdr["xllcorner"] // hdr["cellsize"] + hdr["ncols"]) 

81 maxY = max(maxY, hdr["yllcorner"] // hdr["cellsize"] + hdr["nrows"]) 

82 minX = min(minX, hdr["xllcorner"] // hdr["cellsize"]) 

83 minY = min(minY, hdr["yllcorner"] // hdr["cellsize"]) 

84 

85 # Return answers ... 

86 return minX, maxX, minY, maxY