# Matplotlib

Also refers to official cheatsheat [here](https://matplotlib.org/cheatsheets/)

<center><img src="https://drive.google.com/uc?id=1zKJuabAWhclAXqLNr-usOpQC_WRiFgnP" width="70%" height="70%"></center>

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<div align="center">

| Functional | OOP |
|:-----------:|:-------------:|
| plt.xlabel() | ax.set_xlabel() |
| plt.ylabel() | ax.set_ylabel() |
| plt.xlim() | ax.set_xlim() |
| plt.ylim() | ax.set_ylim() |
| plt.title() | ax.set_title() |

</div>

## 1. General procedure for plotting
To create a 2D line plot, follow these general steps:

1. Call the `plt.figure()` to create a new figure. (optional for `%matplotlib inline`)
2. Generate a sequence of $x$ values usually using `linspace()`.
3. Generate a sequence of $y$ values usually by substitute the x values into a function.
4. Input `plt.plot(x, y, [format], **kwargs)` where `[format]` is an (optional) format string, and `**kwargs` are (optional) keyword arguments specifying the line properties of the plot.
5. Utilize `plt` functions to enhance the figure with features such as a title, legend, grid lines, etc.
6. Input `plt.show()` to display the resulting figure (this step is optional in a Jupyter notebook).

## 2. Plots <a name="plots"></a>

### Creating plots

*Figure* <a name="figure"></a>

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
| `fig = plt.figures()` | a container that contains all plot elements | [link](https://matplotlib.org/stable/api/figure_api.html) |

*Axes* <a name="axes"></a>

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
| `fig.add_axes()`<br/>`a = fig.add_subplot(222)` |Initializes subplot <br/> A subplot is an axes on a grid system <br/> row-col-num | [link](https://matplotlib.org/stable/api/figure_api.html)|
| `fig, b = plt.subplots(nrows=3, nclos=2)`|Adds subplot| [link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.subplot.html)|
|`ax = plt.subplots(2, 2)`|Creates subplot|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.subplot.html)|

### Plotting <a name="1d"></a>

*1D Data* <a name="plotting"></a>

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
| `lines = plt.plot(x,y)`|Plot data connected by lines|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.plot.html)|
| `plt.scatter(x,y)`|Creates a scatterplot, unconnected data points|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.scatter.html)|
|`plt.hist(x, y)`|Plots a histogram|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.hist.html)|
|`plt.fill_between(x,y,color='yellow')`|Fill area under/between plots|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.fill_between.html)|

*Saving plots* <a name="save"></a>

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
|`plt.savefig('pic.png')`|Saves plot/figure to image|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.savefig.html)|

### Customization <a name="custom"></a>

*Color* <a name="colors"></a>

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
| `plt.plot(x, y, color='lightblue')`<br/>`plt.plot(x, y, alpha = 0.4)`|colors plot to color blue|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.plot.html)|
|`plt.colorbar(mappable, orientation='horizontal')`|`mappable`: the Image, Contourset etc to which colorbar applies|[link](https://matplotlib.org/stable/api/colorbar_api.html)|

*Markers* <a name="markers"></a> (see [examples](#examples))

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
| `plt.plot(x, y, marker='*')`|adds `*` for every data point|[link](https://matplotlib.org/stable/api/markers_api.html)|
| `plt.scatter(x, y, marker='.')` |adds . for every data point|see above|

*Lines* <a name="lines"></a>

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
|`plt.plot(x, y, linewidth=2)`|Sets line width|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.plot.html)|
|`plt.plot(x, y, ls='solid')`|Sets linestyle, `ls` can be ommitted, see 2 below|see above|
|`plt.plot(x, y, ls='--')`|Sets linestyle, `ls` can be ommitted, see below|see above|
|`plt.plot(x,y,'--', x**2, y**2, '-.')`|Lines are '--' and '_.'|see above|

*Text* <a name="text"></a>

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
|`plt.text(1, 1,'Example Text',style='italic')`|Places text at coordinates 1/1|[link](https://matplotlib.org/stable/api/text_api.html)|
|`ax.annotate('some annotation', xy=(10, 10))`|Annotate the point with coordinates`xy` with text `s`|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.annotate.html)|
|`plt.title(r'$delta_i=20$', fontsize=10)`|Mathtext|[link](https://matplotlib.org/stable/tutorials/text/mathtext.html)|

*Limits, Legends/Labels , Layout* <a name="lll"></a>

*Limits*

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
|`plt.xlim(0, 7)`|Sets x-axis to display 0 - 7 |[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.xlim.html)|
|`plt.ylim(-0.5, 9)`|Sets y-axis to display -0.5 - 9|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.ylim.html)|
|`ax.set(xlim=[0, 7], ylim=[-0.5, 9])`<br/>`ax.set_xlim(0, 7)`||
|`plt.axis('equal')`|Set the aspect ratio of the plot to 1||

*Legends/Labels*

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
|`plt.title('just a title')`|Sets title of plot|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.title.html)|
|`plt.xlabel('x-axis')`|Sets label next to x-axis|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.xlabel.html)|
|`plt.ylabel('y-axis')`|Sets label next to y-axis|[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.ylabel.html)|
|`plt.legend(loc='best')`|No overlapping plot elements|[link](https://matplotlib.org/stable/api/legend_api.html)|

*Ticks*

| Operator | Description | Documentation |
| :------------- | :------------- | :----------- |
|`plt.xticks(x, labels, rotation='vertical')`| |[link](https://matplotlib.org/stable/api/_as_gen/matplotlib.pyplot.xticks.html)|

## 3. Examples <a name="examples"></a>

### Basics <a name="basics"></a>

import matplotlib.pyplot as plt

x = np.linspace(-2,2,200)
plt.plot(x, np.cos(x - 0), color='blue')         # specify color by name
plt.plot(x, np.cos(x - 1), color='g')            # short color code (rgbcmyk)
plt.plot(x, np.cos(x - 2), color='0.75')         # grayscale between 0 and 1
plt.plot(x, np.cos(x - 4), color=(1.0,0.2,0.3)); # RGB tuple, values 0 to 1


import matplotlib.pyplot as plt

plt.plot(x, np.sin(x), '-g', label='sin(x)') # solid green line
plt.plot(x, np.cos(x), ':b', label='cos(x)') # dotted blue line

plt.title("A Sin/Cos Curve", fontsize=18)       # we can also specify the font size
plt.xlabel("x", fontsize=14)
plt.ylabel("sin(x)", fontsize=14)
plt.legend(fontsize=12)

plt.axis('equal');


import matplotlib.pyplot as plt

plt.plot(x, y, '-vb', markersize=15, linewidth=4, markerfacecolor='orange', markeredgewidth=2)
plt.ylim(-1.2, 1.2);


import matplotlib.pyplot as plt

plt.hist(data, bins=30, density=True, alpha=0.5, color='steelblue', edgecolor='none')
x = np.linspace(-4,4,100)
y = 1/(2*np.pi)**0.5 * np.exp(-x**2/2)
plt.plot(x,y,'b',alpha=0.8);


import matplotlib.pyplot as plt

x = np.linspace(0, 2*np.pi, 1000)

plt.plot(x, np.sin(x), 'r')
plt.plot(x, np.cos(x), 'g')
plt.fill_between(x, np.cos(x), np.sin(x), color='red', alpha=0.1);


import matplotlib.pyplot as plt

t = np.linspace(0, 2*np.pi, 64)
r = np.sin(t)
# plot in polar coordinates
plt.axes(projection='polar')
plt.plot(t+(r<0)*np.pi, np.abs(r), '-')

# Set ticks for polar coordinate
plt.xticks([0, np.pi/2, np.pi, 3*np.pi/2], ['0', '$\pi/2$', '$\pi$', '$3\pi/2$']);


### Subplotting Examples <a name="sub"></a>

import matplotlib.pyplot as plt

fig, ax = plt.subplots(2, 3)
fig.subplots_adjust(hspace=0.4, wspace=0.4)
for i in range(2):
    for j in range(3):
        ax[i, j].text(0.5, 0.5, str((i, j)), fontsize=18, ha='center', va='center')