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--- python [2019/11/21 22:50] – created admin
+++ python [2021/05/06 11:15] (current) – admin
@@ Line 1: / Line 1: @@
-### Plot (matplotlib)
+## Data Type
-  py37-matplotlib has the following notes:
-    The default backend is the interactive Mac OS X backend. Different backends can be specified using the
+^ Example                                       ^ Data Type  ^
-    ~/.matplotlib/matplotlibrc file. More details regarding backends can be found in the matplotlib FAQ:
+| x = "Hello World"                             | str        |
+| x = 20                                        | int        |
-    https://matplotlib.org/tutorials/introductory/usage.html#backends
+| x = 20.5                                      | float      |
+| x = 1j                                        | complex    |
+| x = ["apple", "banana", "cherry"]             | list       |
+| x = ("apple", "banana", "cherry")             | tuple      |
+| x = range(6)                                  | range      |
+| x = {"name" : "John", "age" : 36}             | dict       |
+| x = {"apple", "banana", "cherry"}             | set        |
+| x = frozenset({"apple", "banana", "cherry"})  | frozenset  |
+| x = True                                      | bool       |
+| x = b"Hello"                                  | bytes      |
+| x = bytearray(5)                              | bytearray  |
+| x = memoryview(bytes(5))                      |            |
+ref: https://medium.com/@shawnren527/learn-about-python-3-data-types-numbers-and-strings-76c75a917c9b
+### Class
+ref:https://www.w3schools.com/python/python_classes.asp
+## Create a list of objects from a class
+```python
+   swatchList = []
+   swatchList.append(Swatch("Sky1",22,40,76))
+   # Swatch is the name of the class
+```
+<wrap lo>
+Reference:\\
+ - [[https://www.daniweb.com/programming/software-development/code/216631/a-list-of-class-objects-python|A List of Class Objects]]
+</wrap>
+## Format Variables
+```python
+   print('%s %.2f' % ("hue =",swSky1.hue))
+   print('{0} {1:.2f}'.format("hue =",swSky1.hue))
+   print("hue =", format(swSky1.hue,'.2f'))
+   # f:float, x:hex, s:string
+```
+The three lines above give the same result ````hue = 220.00````.\\
+The first line is the old way, "s" means string and "f" means float. The second line is the new way. 0 in {} refer to the first variable and 1:.2f in {} refers to the second variable swSky1.hue and format it to 2 digits behind decimal point.
+<wrap lo>
+Reference:\\
+ - Using % and .format() for great good!: https://pyformat.info/
+</wrap>
+## Plot (matplotlib)
+py37-matplotlib has the following notes:\\
+The default backend is the interactive Mac OS X backend. Different backends can be specified using the
+~/.matplotlib/matplotlibrc file. More details regarding backends can be found in the matplotlib FAQ:
+https://matplotlib.org/tutorials/introductory/usage.html#backends
+```python
+import matplotlib.pyplot as plt
+plt.plot(x, y, color='black', linestyle = 'none', marker='o', markerfacecolor=(swatch.r/255.0,swatch.g/255.0,swatch.b/255.0), markersize=12)
+```
+Note: ```markerfacecolor``` accept RGB, HEX and simple color text description: ```markerfacecolor=(r,g,b)```, ```markerfacecolor='#333399'```, ``` markerfacecolor='green'```
+### 3D plot:
+https://jakevdp.github.io/PythonDataScienceHandbook/04.12-three-dimensional-plotting.html
+## Common Error
+```python
+    File "main.py", line 15
+    self.sat = (cMax - cMin)/(1-abs(2*self.lum-1))
+                                                 ^
+    TabError: inconsistent use of tabs and spaces in indentation
+```
+{{ ::python_error_1_space_and_tab.png |}}
+Convert all tab to space will solve this problem.