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Merge branch 'master' of github.com:gto76/python-cheatsheet
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‎README.md

Lines changed: 47 additions & 23 deletions
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@@ -561,27 +561,28 @@ from dateutil.tz import UTC, tzlocal, gettz
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```python
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<D/DTn> = D/DT.today() # Current local date or naive datetime.
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<DTn> = DT.utcnow() # Naive datetime from current UTC time.
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<DTa> = DT.now(<tz>) # Aware datetime from current tz time.
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<DTa> = DT.now(<tzinfo>) # Aware datetime from current tz time.
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```
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* **To extract time use `'<DTn>.time()'` or `'<DTa>.timetz()'`.**
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### Timezone
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```python
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<tz> = UTC # UTC timezone. London without DST.
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<tz> = tzlocal() # Local timezone.
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<tz> = gettz('<Cont.>/<City>') # Timezone from 'Continent/City_Name' str.
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<tzinfo> = UTC # UTC timezone. London without DST.
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<tzinfo> = tzlocal() # Local timezone.
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<tzinfo> = gettz('<Cont.>/<City>') # Timezone from 'Continent/City_Name' str.
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```
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```python
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<DTa> = <DT>.astimezone(<tz>) # Datetime, converted to passed timezone.
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<Ta/DTa> = <T/DT>.replace(tzinfo=<tz>) # Unconverted object with new timezone.
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<DTa> = <DT>.astimezone(<tzinfo>) # Datetime, converted to passed timezone.
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<Ta/DTa> = <T/DT>.replace(tzinfo=<tzinfo>) # Unconverted object with new timezone.
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```
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### Encode
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```python
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<D/T/DT> = D/T/DT.fromisoformat('<iso>') # Object from ISO string.
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<DT> = DT.strptime(<str>, '<format>') # Datetime from str, according to format.
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<D/DTn> = D/DT.fromordinal(<int>) # D/DTn from days since Christ.
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<DTa> = DT.fromtimestamp(<real>, <tz>) # DTa from seconds since Epoch in tz time.
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<DTa> = DT.fromtimestamp(<real>, <tz.>) # DTa from seconds since Epoch in tz time.
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```
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* **ISO strings come in following forms: `'YYYY-MM-DD'`, `'HH:MM:SS.ffffff[±<offset>]'`, or both separated by `'T'`. Offset is formatted as: `'HH:MM'`.**
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* **On Unix systems Epoch is `'1970-01-01 00:00 UTC'`, `'1970-01-01 01:00 CET'`, ...**
@@ -601,10 +602,15 @@ from dateutil.tz import UTC, tzlocal, gettz
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>>> dt.strftime("%A, %dth of %B '%y, %I:%M%p %Z")
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"Thursday, 14th of May '15, 11:39PM UTC+02:00"
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```
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* **For abbreviated weekday and month use `'%a'` and `'%b'`.**
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#### Rest of the codes:
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* **`'a'` - Weekday, abbreviated name.**
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* **`'b'` - Month, abbreviated name.**
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### Arithmetics
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```python
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<D/DT> = <D/DT> ± <TD>
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<TD> = <TD> ± <TD>
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<TD> = <TD> */ <real>
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<float> = <TD> / <TD>
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```
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Arguments
@@ -1277,8 +1283,10 @@ Open
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**Opens a file and returns a corresponding file object.**
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```python
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<file> = open('<path>', mode='r', encoding=None)
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<file> = open('<path>', mode='r', encoding=None, endline=None)
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```
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* **`'encoding=None'` means default encoding is used, which is platform dependent. Best practice is to use `'encoding="utf-8"'` whenever possible.**
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* **`'endline=None'` means all different end of line combinations are converted to '\n' on read, while on write all '\n' characters are converted to system's default line separator.**
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### Modes
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* **`'r'` - Read (default).**
@@ -1295,7 +1303,8 @@ Open
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```python
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<file>.seek(0) # Moves to the start of the file.
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<file>.seek(offset) # Moves 'offset' chars/bytes from the start.
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<file>.seek(offset, <anchor>) # Anchor: 0 start, 1 current pos., 2 end.
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<file>.seek(0, 2) # Moves to the end of the file.
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<bin_file>.seek(±offset, <anchor>) # Anchor: 0 start, 1 current pos., 2 end.
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```
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```python
@@ -1307,10 +1316,10 @@ Open
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```python
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<file>.write(<str/bytes>) # Writes a string or bytes object.
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<file>.writelines(<list>) # Writes a list of strings or bytes objects.
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<file>.writelines(<coll.>) # Writes a coll. of strings or bytes objects.
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<file>.flush() # Flushes write buffer.
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```
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* **Methods do not add or strip trailing newlines.**
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* **Methods do not add or strip trailing newlines, even writelines().**
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### Read Text from File
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```python
@@ -1331,21 +1340,26 @@ Path
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----
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```python
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from os import path, listdir
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from glob import glob
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```
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```python
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<bool> = path.exists('<path>')
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<bool> = path.isfile('<path>')
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<bool> = path.isdir('<path>')
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<list> = listdir('<path>')
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```
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```python
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>>> from glob import glob
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>>> glob('../*.gif')
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['1.gif', 'card.gif']
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<list> = listdir('<path>') # List of filenames located at 'path'.
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<list> = glob('<pattern>') # Filenames matching the wildcard pattern.
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```
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### Pathlib
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```python
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from pathlib import Path
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```
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```python
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cwd = Path()
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<Path> = Path('<path>' [, '<path>', <Path>, ...])
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<Path> = <Path> / '<dir>' / '<file>'
@@ -1355,11 +1369,11 @@ cwd = Path()
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<bool> = <Path>.exists()
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<bool> = <Path>.is_file()
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<bool> = <Path>.is_dir()
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<iter> = <Path>.iterdir()
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```
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```python
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<iter> = <Path>.glob('<pattern>')
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<iter> = <Path>.iterdir() # Iterator of filenames located at path.
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<iter> = <Path>.glob('<pattern>') # Filenames matching the wildcard pattern.
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```
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```python
@@ -1711,7 +1725,7 @@ class MyMetaClass(type):
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* **New() can also be called directly, usually from a new() method of a child class (**`def __new__(cls): return super().__new__(cls)`**), in which case init() is not called.**
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### Metaclass Attribute
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**When class is created it checks if it has metaclass defined. If not, it recursively checks if any of his parents has it defined and eventually comes to type().**
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**Right before a class is created it checks if it has metaclass defined. If not, it recursively checks if any of his parents has it defined and eventually comes to type().**
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```python
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class MyClass(metaclass=MyMetaClass):
@@ -1723,7 +1737,12 @@ class MyClass(metaclass=MyMetaClass):
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('abcde', 12345)
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```
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#### Type diagram (str is an instance of type, ...):
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### Type Diagram
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```python
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type(MyClass) == MyMetaClass # MyClass is an instance of MyMetaClass.
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type(MyMetaClass) == type # MyMetaClass is an instance of type.
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```
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```text
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+---------+-------------+
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| Classes | Metaclasses |
@@ -1736,7 +1755,12 @@ class MyClass(metaclass=MyMetaClass):
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+---------+-------------+
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```
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#### Inheritance diagram (str is a subclass of object, ...):
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### Inheritance Diagram
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```python
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MyClass.__base__ == object # MyClass is a subclass of object.
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MyMetaClass.__base__ == type # MyMetaClass is a subclass of type.
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```
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```text
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+---------+-------------+
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| Classes | Metaclasses |

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