1 files changed, 159 insertions, 0 deletions
diff --git a/generate.py b/generate.py
new file mode 100755
index 0000000..6a91099
--- /dev/null
+++ b/generate.py
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+#!/usr/bin/env python
+#
+#  Copyright 2023 The original authors
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+
+# Based on https://github.com/gunnarmorling/1brc/blob/main/src/main/java/dev/morling/onebrc/CreateMeasurements.java
+
+import os
+import sys
+import random
+import time
+
+
+def check_args(file_args):
+    """
+    Sanity checks out input and prints out usage if input is not a positive integer
+    """
+    try:
+        if len(file_args) != 2 or int(file_args[1]) <= 0:
+            raise Exception()
+    except:
+        print("Usage:  create_measurements.sh <positive integer number of records to create>")
+        print("        You can use underscore notation for large number of records.")
+        print("        For example:  1_000_000_000 for one billion")
+        exit()
+
+
+def build_weather_station_name_list():
+    """
+    Grabs the weather station names from example data provided in repo and dedups
+    """
+    station_names = []
+    with open('./weather_stations.csv', 'r') as file:
+        file_contents = file.read()
+    for station in file_contents.splitlines():
+        if "#" in station:
+            next
+        else:
+            station_names.append(station.split(';')[0])
+    return list(set(station_names))
+
+
+def convert_bytes(num):
+    """
+    Convert bytes to a human-readable format (e.g., KiB, MiB, GiB)
+    """
+    for x in ['bytes', 'KiB', 'MiB', 'GiB']:
+        if num < 1024.0:
+            return "%3.1f %s" % (num, x)
+        num /= 1024.0
+
+
+def format_elapsed_time(seconds):
+    """
+    Format elapsed time in a human-readable format
+    """
+    if seconds < 60:
+        return f"{seconds:.3f} seconds"
+    elif seconds < 3600:
+        minutes, seconds = divmod(seconds, 60)
+        return f"{int(minutes)} minutes {int(seconds)} seconds"
+    else:
+        hours, remainder = divmod(seconds, 3600)
+        minutes, seconds = divmod(remainder, 60)
+        if minutes == 0:
+            return f"{int(hours)} hours {int(seconds)} seconds"
+        else:
+            return f"{int(hours)} hours {int(minutes)} minutes {int(seconds)} seconds"
+
+
+def estimate_file_size(weather_station_names, num_rows_to_create):
+    """
+    Tries to estimate how large a file the test data will be
+    """
+    total_name_bytes = sum(len(s.encode("utf-8")) for s in weather_station_names)
+    avg_name_bytes = total_name_bytes / float(len(weather_station_names))
+
+    # avg_temp_bytes = sum(len(str(n / 10.0)) for n in range(-999, 1000)) / 1999
+    avg_temp_bytes = 4.400200100050025
+
+    # add 2 for separator and newline
+    avg_line_length = avg_name_bytes + avg_temp_bytes + 2
+
+    human_file_size = convert_bytes(num_rows_to_create * avg_line_length)
+
+    return f"Estimated max file size is:  {human_file_size}."
+
+
+def build_test_data(weather_station_names, num_rows_to_create):
+    """
+    Generates and writes to file the requested length of test data
+    """
+    start_time = time.time()
+    coldest_temp = -99.9
+    hottest_temp = 99.9
+    station_names_10k_max = random.choices(weather_station_names, k=10_000)
+    batch_size = 10000 # instead of writing line by line to file, process a batch of stations and put it to disk
+    chunks = num_rows_to_create // batch_size
+    print('Building test data...')
+
+    try:
+        with open("./measurements.txt", 'w') as file:
+            progress = 0
+            for chunk in range(chunks):
+                
+                batch = random.choices(station_names_10k_max, k=batch_size)
+                prepped_deviated_batch = '\n'.join([f"{station};{random.uniform(coldest_temp, hottest_temp):.1f}" for station in batch]) # :.1f should quicker than round on a large scale, because round utilizes mathematical operation
+                file.write(prepped_deviated_batch + '\n')
+                
+                # Update progress bar every 1%
+                if (chunk + 1) * 100 // chunks != progress:
+                    progress = (chunk + 1) * 100 // chunks
+                    bars = '=' * (progress // 2)
+                    sys.stdout.write(f"\r[{bars:<50}] {progress}%")
+                    sys.stdout.flush()
+        sys.stdout.write('\n')
+    except Exception as e:
+        print("Something went wrong. Printing error info and exiting...")
+        print(e)
+        exit()
+    
+    end_time = time.time()
+    elapsed_time = end_time - start_time
+    file_size = os.path.getsize("./measurements.txt")
+    human_file_size = convert_bytes(file_size)
+ 
+    print("Test data successfully written to measurements.txt")
+    print(f"Actual file size:  {human_file_size}")
+    print(f"Elapsed time: {format_elapsed_time(elapsed_time)}")
+
+
+def main():
+    """
+    main program function
+    """
+    check_args(sys.argv)
+    num_rows_to_create = int(sys.argv[1])
+    weather_station_names = []
+    weather_station_names = build_weather_station_name_list()
+    print(estimate_file_size(weather_station_names, num_rows_to_create))
+    build_test_data(weather_station_names, num_rows_to_create)
+    print("Test data build complete.")
+
+
+if __name__ == "__main__":
+    main()
+exit()