convert_longitude¶

• some files (espicially netcdf files) uses longitude values from 0 degrees to 360 degrees, instead of the usual, GIS-standard, arrangement of -180 degrees to 180 degrees for longitude centered on the Prime Meridian, and -90 degrees to 90 degrees for latitude centered on the Equator. the convert_longitude method corrects such behavior.

• to run this notebook make sure that the currect work directory points to the root directory of the pyramids package

In [10]:

# NBVAL_IGNORE_OUTPUT
from pyramids.dataset import Dataset

path = r"../../../examples/data/geotiff/noah-precipitation-1979.tif"

# NBVAL_IGNORE_OUTPUT from pyramids.dataset import Dataset path = r"../../../examples/data/geotiff/noah-precipitation-1979.tif"

Read the raster file¶

In [11]:

dataset = Dataset.read_file(path)

dataset = Dataset.read_file(path)

In [12]:

print(dataset)

print(dataset)

            Top Left Corner: (0.0, 90.0)
            Cell size: 0.5
            Dimension: 360 * 720
            EPSG: 4326
            Number of Bands: 4
            Band names: ['Band_1', 'Band_2', 'Band_3', 'Band_4']
            Band colors: {0: 'gray_index', 1: 'undefined', 2: 'undefined', 3: 'undefined'}
            Band units: ['', '', '', '']
            Scale: [1.0, 1.0, 1.0, 1.0]
            Offset: [0, 0, 0, 0]
            Mask: -9.969209968386869e+36
            Data type: float32
            File: ../../examples/data/geotiff/noah-precipitation-1979.tif
        

In [13]:

print(f"Min longitude: {min(dataset.lon)}")
print(f"Max longitude: {max(dataset.lon)}")

print(f"Min longitude: {min(dataset.lon)}") print(f"Max longitude: {max(dataset.lon)}")

Min longitude: 0.25
Max longitude: 359.75

Plot the first band in the raster¶

In [14]:

array_glyph = dataset.plot(
    band=0,
    figsize=(10, 5),
    title="NOAH daily Precipitation 1979-01-01",
    cbar_label="Rainfall mm/day",
    vmax=30,
    cbar_length=0.85,
)

array_glyph = dataset.plot( band=0, figsize=(10, 5), title="NOAH daily Precipitation 1979-01-01", cbar_label="Rainfall mm/day", vmax=30, cbar_length=0.85, )

use the convert_longitude to convert the longitude values to range between -180 and 180.¶

In [15]:

new_dataset = dataset.convert_longitude()

new_dataset = dataset.convert_longitude()

In [16]:

new_dataset.plot(
    band=0,
    figsize=(10, 5),
    title="NOAH daily Precipitation 1979-01-01",
    cbar_label="RainFall mm/day",
    vmax=30,
    cbar_length=0.85,
)

new_dataset.plot( band=0, figsize=(10, 5), title="NOAH daily Precipitation 1979-01-01", cbar_label="RainFall mm/day", vmax=30, cbar_length=0.85, )

Out[16]:

<cleopatra.array_glyph.ArrayGlyph at 0x22ebbbb9810>

In [17]:

print(f"Min longitude: {min(new_dataset.lon)}")
print(f"Max longitude: {max(new_dataset.lon)}")

print(f"Min longitude: {min(new_dataset.lon)}") print(f"Max longitude: {max(new_dataset.lon)}")

Min longitude: -179.75
Max longitude: 179.75

In [18]:

new_dataset.to_file(
    "../../../examples/data/geotiff/noah-precipitation-1979-corrected.tif"
)

new_dataset.to_file( "../../../examples/data/geotiff/noah-precipitation-1979-corrected.tif" )