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-rw-r--r--quality_control/checks.py51
1 files changed, 51 insertions, 0 deletions
diff --git a/quality_control/checks.py b/quality_control/checks.py
new file mode 100644
index 0000000..28b9ab5
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+++ b/quality_control/checks.py
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+"""Quality control checks for data."""
+import re
+from typing import Optional
+
+def decimal_places_pattern(mini: int, maxi: Optional[int] = None) -> re.Pattern:
+ """
+ Generate a regular expression for checking numbers
+
+ Generates a regular expression that matches:
+ a) Whole numbers, e.g. 2, 54343, 25, etc
+ b) Zeroes e.g. 0, 000, 0.0, 0.000, 0.00000, etc
+ c) Numbers with at least 'mini' decimal places
+ d) If 'maxi' is provided, then numbers with decimal places between
+ 'mini' and 'maxi'.
+
+ To test for a match of exactly 'n' decimal places, then both 'mini' and
+ 'maxi' should be set to 'n'.
+
+ ARGUMENTS:
+ - mini [int]: The mini number of decimal places allowed. This is
+ mandatory.
+ - maxi [int]: The maxi number of decimal places allowed. This is an
+ optional argument. If not provided, then an infinite (theoretically)
+ number of decimal places is allowed.
+ """
+ try:
+ assert isinstance(mini, int), "The argument 'mini' MUST be a integer"
+ assert maxi is None or isinstance(maxi, int), "The argument 'maxi' MUST be a integer"
+ except AssertionError as exc:
+ raise TypeError(*exc.args) from exc
+
+ try:
+ assert mini > 0, "The argument 'mini' must be greater than zero (0)."
+ if isinstance(maxi, int):
+ assert maxi > 0, "The argument 'maxi' must be greater than zero (0)."
+ assert maxi >= mini, "'maxi' MUST be greater than or equal to 'mini'."
+ except AssertionError as exc:
+ raise ValueError(*exc.args) from exc
+
+ return re.compile(
+ r"^("
+ r"0+" # All zeroes, no decimal places
+ + r"|0+\.0+" # 0.00…
+ + r"|[0-9]+\.?0*" # Whole numbers, or all zeroes after decimal point
+ + r"|[0-9]+\.[0-9]{"
+ + str(mini)
+ + r","
+ + (str(maxi) if maxi is not None else r"")
+ + r"}"
+ + r")$"
+ )