rasterio read string directly

Question

Usually, I read ascii from files with something like:

asc = rasterio.open(filepath)
array = asc.read(1)

But in some cases, all the lines of the ascii file have already been read into a variable like below:

with open(filepath) as file:
    lines = [line.upper() for line in file.readlines()]
asc_src = "".join(lines)

Is there a way to make asc from asc_source directly? I could write it to a temporary ascii file and read it back but I'd like to avoid it if possible.

Answer 1

You can use a MemoryFile as described in the documentation:

from rasterio.io import MemoryFile

data = b"""\
NCOLS 16
NROWS 16
XLLCORNER 378922
YLLCORNER 4072345
CELLSIZE 30
NODATA_VALUE -9999
43 2 45 7 3 56 2 5 23 65 34 6 32 54 57 34
35 45 65 34 2 6 78 4 2 6 89 3 2 7 45 23 5
43 2 45 7 3 56 2 5 23 65 34 6 32 54 57 34
35 45 65 34 2 6 78 4 2 6 89 3 2 7 45 23 5
43 2 45 7 3 56 2 5 23 65 34 6 32 54 57 34
35 45 65 34 2 6 78 4 2 6 89 3 2 7 45 23 5
43 2 45 7 3 56 2 5 23 65 34 6 32 54 57 34
35 45 65 34 2 6 78 4 2 6 89 3 2 7 45 23 5
43 2 45 7 3 56 2 5 23 65 34 6 32 54 57 34
35 45 65 34 2 6 78 4 2 6 89 3 2 7 45 23 5
43 2 45 7 3 56 2 5 23 65 34 6 32 54 57 34
35 45 65 34 2 6 78 4 2 6 89 3 2 7 45 23 5
43 2 45 7 3 56 2 5 23 65 34 6 32 54 57 34
35 45 65 34 2 6 78 4 2 6 89 3 2 7 45 23 5
43 2 45 7 3 56 2 5 23 65 34 6 32 54 57 34
35 45 65 34 2 6 78 4 2 6 89 3 2 7 45 23 5
"""

with MemoryFile(data) as memfile:
    with memfile.open() as dataset:
        print(dataset.shape)
        print(dataset.transform)

        data_array = dataset.read()
        print(data_array.dtype)

(16, 16)
| 30.00, 0.00, 378922.00|
| 0.00,-30.00, 4072825.00|
| 0.00, 0.00, 1.00|
int32