Create README.md

Signed-off-by: David Rotermund <54365609+davrot@users.noreply.github.com>

python_basics/formatted_string_literals/README.md

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+# Python : Formatted String Literals
+{:.no_toc}
+
+<nav markdown="1" class="toc-class">
+* TOC
+{:toc}
+</nav>
+
+## The goal
+Using formated string literals is an easy way to produce formated strings from data / variables.
+
+Questions to [David Rotermund](mailto:davrot@uni-bremen.de)
+
+## Basic Formatted String Literals
+A formatted string literals starts with an f and the variables that you want to print are placed at their intended position embeded into { }.  For example:
+
+```python
+import numpy as np
+
+a: str = "Hello"
+b: int = 1
+c: float = np.pi
+
+mystring: str = f"A: {a} B: {b} C: {c}"
+print(mystring)
+```
+
+```python
+A: Hello B: 1 C: 3.141592653589793
+```
+
+In the case the string is to long (i.e. longer than the 80 character limit), you can use this construct to break the line into several lines:
+
+```python
+import numpy as np
+
+a: str = "Hello"
+b: int = 1
+c: float = np.pi
+
+
+mystring: str = (
+    f"Variable A: {a} " 
+    "Blablablablabla " 
+    f"Variable B: {b} " 
+    f"Variable C: {c} "
+)
+
+print(mystring)
+```
+
+```python
+Variable A: Hello Blablablablabla Variable B: 1 Variable C: 3.141592653589793
+```
+
+## [Formats](https://docs.python.org/3/library/string.html#formatspec)
+
+```python
+format_spec     ::=  [[fill]align][sign][#][0][width][grouping_option][.precision][type]
+fill            ::=  <any character>
+align           ::=  "<" | ">" | "=" | "^"
+sign            ::=  "+" | "-" | " "
+width           ::=  digit+
+grouping_option ::=  "_" | ","
+precision       ::=  digit+
+type            ::=  "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g" | "G" | "n" | "o" | "s" | "x" | "X" | "%"
+```
+
+### Integer formats
+
+|||
+|---|---|
+|'b'|	Binary format.|
+|'c'|	Character.|
+|'d'|	Decimal Integer.|
+|'o'|	Octal format.|
+|'x'|	Hex format. |
+|'X'|	Hex format. |
+|'n'|	Number.|
+|**None**|	**'d'**|
+
+|||
+|---|---|
+|'+'|	indicates that a sign should be used for both positive as well as negative numbers.|
+|'-'|	indicates that a sign should be used only for negative numbers (this is the default behavior).|
+|space|	indicates that a leading space should be used on positive numbers, and a minus sign on negative numbers.|
+
+|||
+|---|---|
+|'<'|	Forces the field to be left-aligned within the available space (this is the default for most objects).|
+|'>'|	Forces the field to be right-aligned within the available space (this is the default for numbers).|
+|'='|	Forces the padding to be placed after the sign (if any) but before the digits.|
+|'^'|	Forces the field to be centered within the available space.|
+
+### Float formats
+
+|||
+|---|---|
+|'e'|	Scientific notation.|
+|'E'|	Scientific notation.|
+|**'f'**|	**Fixed-point notation.**|
+|'F'|	Fixed-point notation.|
+|'g'|	General format.|
+|'G'|	General format.|
+|'n'|	Number.|
+|'%'|	Percentage. |
+|None|	'g'|
+
+|||
+|---|---|
+|'+'|	indicates that a sign should be used for both positive as well as negative numbers.|
+|'-'|	indicates that a sign should be used only for negative numbers (this is the default behavior).|
+|space|	indicates that a leading space should be used on positive numbers, and a minus sign on negative numbers.|
+
+```python
+import numpy as np
+
+value: float = np.pi
+
+print(f"{value}")
+print(f"{value:.3f}")
+print(f"{value:+.3f}")
+print(f"{-value:+.3f}")
+```
+
+```python
+3.141592653589793
+3.142
++3.142
+-3.142
+```
+
+```python
+import numpy as np
+
+value: float = np.pi
+
+print(f"{value:>30.2f}")
+print(f"{value:<30.2f}")
+print(f"{value:=30.2f}")
+print(f"{value:^30.2f}")
+```
+
+```python
+                          3.14
+3.14                          
+                          3.14
+             3.14             
+```
+
+### String formats
+
+|||
+|---|---|
+|'s'|	String format.|
+|**None** |	**'s'**|
+
+### Dates
+
+```python
+# %%
+from datetime import datetime
+
+d = datetime.now()
+print(f"{d:%Y-%m-%d %H:%M:%S}")
+```
+
+```python
+2022-04-03 01:18:45
+```
+
+| Directive | Meaning | Example |
+|---|---|---|
+|%a|Weekday as locale’s abbreviated name.|Sun, Mon, …, Sat (en_US); So, Mo, …, Sa (de_DE) |
+|%A|Weekday as locale’s full name.|Sunday, Monday, …, Saturday (en_US);Sonntag, Montag, …, Samstag (de_DE)|
+|%w|Weekday as a decimal number, where 0 is Sunday and 6 is Saturday.| 0, 1, …, 6 |
+|%d|Day of the month as a zero-padded decimal number.|01, 02, …, 31 |
+|%b|Month as locale’s abbreviated name.|Jan, Feb, …, Dec (en_US); Jan, Feb, …, Dez (de_DE) | 
+|%B|Month as locale’s full name.|January, February, …, December (en_US); Januar, Februar, …, Dezember (de_DE) |
+|%m|Month as a zero-padded decimal number.|01, 02, …, 12|
+|%y|Year without century as a zero-padded decimal number.|00, 01, …, 99|
+|%Y|Year with century as a decimal number.|0001, 0002, …, 2013, 2014, …, 9998, 9999|
+|%H|Hour (24-hour clock) as a zero-padded decimal number.|00, 01, …, 23|
+|%I|Hour (12-hour clock) as a zero-padded decimal number.|01, 02, …, 12|
+|%p|Locale’s equivalent of either AM or PM.| AM, PM (en_US); am, pm (de_DE)|
+|%M|Minute as a zero-padded decimal number.|00, 01, …, 59|
+|%S| Second as a zero-padded decimal number. | 00, 01, …, 59 |
+|%f|Microsecond as a decimal number, zero-padded to 6 digits.|000000, 000001, …, 999999|
+|%z|UTC offset in the form ±HHMM[SS[.ffffff]] (empty string if the object is naive).|(empty), +0000, -0400, +1030, +063415, -030712.345216|
+|%Z|Time zone name (empty string if the object is naive).|(empty), UTC, GMT|
+|%j|Day of the year as a zero-padded decimal number.|001, 002, …, 366|
+|%U|Week number of the year (Sunday as the first day of the week) as a zero-padded decimal number. All days in a new year preceding the first Sunday are considered to be in week 0.|00, 01, …, 53|
+|%W|Week number of the year (Monday as the first day of the week) as a zero-padded decimal number. All days in a new year preceding the first Monday are considered to be in week 0.| 00, 01, …, 53|
+|%c|Locale’s appropriate date and time representation. | Tue Aug 16 21:30:00 1988 (en_US); Di 16 Aug 21:30:00 1988 (de_DE) |
+|%x|Locale’s appropriate date representation. | 08/16/88 (None); 08/16/1988 (en_US); 16.08.1988 (de_DE) |
+|%X|Locale’s appropriate time representation. | 21:30:00 (en_US); 21:30:00 (de_DE) |
+|%%|A literal '%' character.|%|
+
+see [here](https://docs.python.org/3/library/datetime.html#strftime-and-strptime-format-codes) for the date formats 
+
+## Reference
+* [Formatted String Literals](https://docs.python.org/3/tutorial/inputoutput.html#formatted-string-literals)
+* [Format Specification Mini-Language](https://docs.python.org/3/library/string.html#formatspec)