Develop Reference

create multiple cells in a loop in notebook [duplicate]

I would like to plot two or more graphs at once using python and matplotlib. I do not want to use subplot since it is actually two or more plots on the same drawing paper.
Is there any way to do it?

You can use multiple figures and plot some data in each of them. The easiest way of doing so is to call plt.figure() and use the pyplot statemachine.
import matplotlib.pyplot as plt
plt.figure() # creates a figure
plt.plot([1,2,3])
plt.figure() # creates a new figure
plt.plot([3,2,1])
plt.show() # opens a window for each of the figures
If for whatever reason after creating a second figure you want to plot to the first one, you need to 'activate' it via
plt.figure(1)
plt.plot([2,3,1]) # this is plotted to the first figure.
(Figure numbers start at 1)

Python Heatmaps (Basic and Complex)

What's the best way to do a heatmap in python (2.7)? I've found the heatmap.py module, and I was wondering if people have any advice on using it, or if there are other packages that do a good job.
I'm dealing with pretty basic data, like xy = np.random.rand(1000,2) superimposed on an image.
Although there's another thing I want to try, which is doing a heatmap that's scaled to a different heatmap. E.g., I have
attempts = np.random.rand(5000,2)
successes = np.random.rand(500,2)
And I want a heatmap of the successes relative to the density of the attempts. Is this possible?

Seaborn is a pretty widely-used library for making nice-looking plots, and has a heatmap function. Seaborn uses matplotlib under the hood.
import numpy as np
import seaborn as sns
xy = np.random.rand(1000,2)
sns.heatmap(xy, yticklabels=100)
Regarding your second question, I'm not sure what you mean. But my advice would be to create a numpy array or pandas dataframe of "successes [scaled] relative to the density of the attempts", however you mean that, and then pass that scaled array or dataframe to sns.heatmap

You can plot very complex heatmap using python package PyComplexHeatmap: https://github.com/DingWB/PyComplexHeatmap
https://github.com/DingWB/PyComplexHeatmap/blob/main/examples.ipynb

The most basic heatmap you can get is an image plot:
import matplotlib.pyplot as plt
import numpy as np
xy = np.random.rand(100,2)
plt.imshow(xy, aspect="auto")
plt.colorbar()
plt.show()
Note that using more points than you have pixels to show the heatmap might not make too much sense.
There are of course also different methods to draw a heatmaps and you may go through the matplotlib example gallery and see which plot appeals most to you.

Plotting scatter graph with marginal histograms with Python seaborn 0.7

I have some python code that plotted a scatter graph with marginal histograms. This worked fine with seaborn 0.5 and still does work if I go back to this version. However, I'd like to get it to work with 0.7!
I don't use python often and mainly only use scripts set up by others that I adjust slightly.
The problem appears to be happening in the following line:
sns.lmplot(x='Moisture Content (%)', y='Dry Density (kg/m3)', hue='Test',
data=data, ax=ax_joint, fit_reg=False, legend=False, palette=test_colours)
ax is no longer recognised in seaborn 0.7.
TypeError: lmplot() got an unexpected keyword argument 'ax'
The output still gives me completed marginal histograms but the scatter graph is blank.
If you need more info then please let me know.
Cheers

seaborn lmplot ax will show you that lmplot returns you a figure-level instead of axes-level. So in order to manage lmplot use FacetGrid.
FacetGrid will plot on different variables that you states in different graphs.
import matplotlib.pyplot as plt
g = sns.FacetGrid(tips, col="time", row="smoker")
g = g.map(plt.hist, "total_bill")
FacetGrid result image
You can imagine doing a groupby on the dataframe which gives you the different graphs.
Refer to this for more example on plotting lmplot

creating a chart with high/low and percentile box plus other points

Hi I'd like to recreate the following plot with matplotlib and pandas.
I started to use boxplot but i'm struggling to manipulate the kwargs.
Is there a simple way to use boxplot or do I need to recreate the chart enitrely.
One issue I had was also adding the current data?
Best regards

The boxplot from matplotlib has indeed some limitations. For you to have full control over how the plot looks I would advise using Patches to draw Rectangles for example (code from Rectangles link):
import matplotlib.pyplot as plt
import matplotlib.patches as patches
fig1 = plt.figure()
ax1 = fig1.add_subplot(111, aspect='equal')
ax1.add_patch(
patches.Rectangle(
(0.1, 0.1), # (x,y)
0.5, # width
0.5, # height
)
)
fig1.savefig('rect1.png', dpi=90, bbox_inches='tight')
This is useful because you'll only need this and a normal plot command (for lines) in matplotlib to do a boxplot. This will give you immense control about color and shape and it's fairly easy to build. You also have text there you'll need for which you can use matplotlib text. The last thing are those markers which are very doable with a scatter.
A boxplot is a shape that tells you information such a minimum, maximum, and percentiles (25,50,75). You can calculate this very easily with numpy percentile.
The details of the plot (labels at the bottom, legend, title in box, and so on) can also be achieved but tinkering with labels, manually building a title box and so on.
It will give you some work but these are the commands you need.

Pyplot/Subplot APIs Matplotlib

I'm making something using Matplotlib where I have multiple subplots on a figure. It seems to me like the subplot API is limited compared to the PyPlot API: for example, I can't seem to make custom axes labels in my subplot although it is possible using PyPlot.
My question is: Is there a richer subplot API besides the tiny one on the PyPlot page (http://matplotlib.org/api/pyplot_api.html), and/or is there a way to get the full functionality of a PyPlot on a subplot?
Basically, what is a subplot? I can't find it in the documentation. Even more generally, when should I use a figure vs an axis vs a subplot? They all seem to do essentially the same thing.
Consider the following code:
import matplotlib.pyplot as plt
fig = plt.figure()
ax = fig.add_subplot(2,1,1)
Then ax is an axis? Can I use the pyplot API to customize ax?
Thanks for your help.

While i suggest that use the axes methods, there is the plt.sca function (set current axes).
So
plt.sca(ax)
does what you want, i think.