Add lazy SQL → xarray round-trip via XarrayDataFrame.to_dataset (closes #58)

README.md

@@ -57,52 +57,37 @@ ctx.sql('''
 # 0  8.640069
 
 # Average temperature per pressure level, globally. 
-ctx.sql('''
+result = ctx.sql('''
   SELECT level, AVG(temperature) - 273.15 AS avg_c
   FROM era5.atmosphere
   WHERE time BETWEEN TIMESTAMP '2020-01-01'
                  AND TIMESTAMP '2020-01-01 05:00:00'
   GROUP BY level
   ORDER BY level DESC
-''').to_pandas()
-#     level      avg_c
-# 0    1000   6.621012   ← surface
-# 1     975   5.185638
-# 2     950   4.028429
-# 3     925   3.082812
-# 4     900   2.210917
-# 5     875   1.395018
-# 6     850   0.634267
-# 7     825  -0.210372
-# 8     800  -1.181075
-# 9     775  -2.306465
-# 10    750  -3.535534
-# 11    700  -6.241685
-# 12    650  -9.236364
-# 13    600 -12.580938
-# 14    550 -16.335386
-# 15    500 -20.643604
-# 16    450 -25.573401
-# 17    400 -31.156920
-# 18    350 -37.400552
-# 19    300 -43.852607
-# 20    250 -49.322132
-# 21    225 -51.569113
-# 22    200 -53.693248
-# 23    175 -55.890484
-# 24    150 -58.382290
-# 25    125 -61.091916
-# 26    100 -63.624885   ← tropopause
-# 27     70 -63.182300
-# 28     50 -60.124845
-# 29     30 -55.986327
-# 30     20 -52.433089
-# 31     10 -44.140750
-# 32      7 -38.707350
-# 33      5 -32.621999
-# 34      3 -21.509175
-# 35      2 -13.355764
-# 36      1  -9.020513   ← top of atmosphere
+''')
+# DataFrame()
+# +-------+----------------------+
+# | level | avg_c                |
+# +-------+----------------------+
+# | 1000  | 6.6210120796502565   |
+# | 975   | 5.185637919348153    |
+# | 950   | 4.028428657263021    |
+# | 925   | 3.0828117974912743   |
+# | 900   | 2.2109172992531967   |
+# | 875   | 1.395017610194202    |
+# | 850   | 0.6342670572626616   |
+# | 825   | -0.21037158786759846 |
+# | 800   | -1.1810754318269687  |
+# | 775   | -2.3064649711534457  |
+# +-------+----------------------+
+
+avg_temp_ds = result.to_dataset(dims=["level"])
+# <xarray.Dataset> Size: 592B
+# Dimensions:  (level: 37)
+# Coordinates:
+#   * level    (level) int64 296B 1000 975 950 925 900 875 850 ... 20 10 7 5 3 2 1
+# Data variables:
+#     avg_c    (level) float64 296B 6.621 5.186 4.028 ... -21.51 -13.36 -9.021
 ```
 
 _(A runnable version of this example lives at
@@ -211,6 +196,8 @@ I want to give a special thanks to the following folks and institutions:
   who are working to make this library better.
 - Andrew Huang for the sense of taste he brings to the project and consummate code
   changes.
+- Aman Kumar for spending a considerable amount of his GSoC internship 
+  contributing to this project. 
 
 
 ## License

pyproject.toml

@@ -90,6 +90,7 @@ module = [
     "pyarrow.*",
     "datafusion.*",
     "xarray.*",
+    "pandas.*",
 ]
 ignore_missing_imports = true