Added read_csv.py example

home/public/snippits/python/read_csv.py

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+#! /usr/bin/env python
+# Sample of reading a CSV file
+#
+# https://stackoverflow.com/questions/41585078/how-do-i-read-and-write-csv-files-with-python
+#
+
+import csv
+import sys
+
+files = sys.argv[1:]
+
+if len(files) == 0:
+    sys.stderr.write("Usage: read_csv.py file [file...]\n")
+    sys.exit(1)
+
+MAXLINES = 10000
+
+# # Define data
+# data = [
+#     (1, "A towel,", 1.0),
+#     (42, " it says, ", 2.0),
+#     (1337, "is about the most ", -1),
+#     (0, "massively useful thing ", 123),
+#     (-2, "an interstellar hitchhiker can have.", 3),
+# ]
+
+# # Write CSV file
+# with open("test.csv", "wt") as fp:
+#     writer = csv.writer(fp, delimiter=",")
+#     # writer.writerow(["your", "header", "foo"])  # write header
+#     writer.writerows(data)
+
+# Read CSV file
+
+for file in files:
+    with open(file) as fp:
+        reader = csv.reader(fp, delimiter=",", quotechar='"')
+        # next(reader, None)  # skip the headers
+        # data_read = [row for row in reader]
+
+        # print(data_read)
+
+        lineno = 0
+        num_column_headrs = 0
+        print_first_n = 5
+
+        for row in reader:
+            lineno += 1
+
+            if lineno == 1:
+                num_column_headers = len(row)
+
+            len_row = len(row)
+            if len_row != num_column_headers:
+                sys.stderr.write(f"Bad coumn count: line {lineno} has {len_row} colums.  Expecting {num_column_headers}\n")
+                print(row)
+                sys.exit()
+
+            if lineno <= print_first_n:
+                print(row)
+
+            if lineno > MAXLINES:
+                break
+
+        sys.stderr.write(f"Done: read {lineno} lines.\n")