n3utrino n3utrino - 3 years ago 159
Python Question

Creating Pandas Dataframe between two Numpy arrays, then draw scatter plot

I'm relatively new with numpy and pandas (I'm an experimental physicist so I've been using ROOT for years...).
A common plot in ROOT is a 2D scatter plot where, given a list of x- and y- values, makes a "heatmap" type scatter plot of one variable versus the other.

How is this best accomplished with numpy and Pandas? I'm trying to use the

Dataframe.plot()
function, but I'm struggling to even create the Dataframe.

import numpy as np
import pandas as pd
x = np.random.randn(1,5)
y = np.sin(x)
df = pd.DataFrame(d)


First off, this dataframe has shape (1,2), but I would like it to have shape (5,2).
If I can get the dataframe the right shape, I'm sure I can figure out the
DataFrame.plot()
function to draw what I want.

Answer Source

There are a number of ways to create DataFrames. Given 1-dimensional column vectors, you can create a DataFrame by passing it a dict whose keys are column names and whose values are the 1-dimensional column vectors:

import numpy as np
import pandas as pd
x = np.random.randn(5)
y = np.sin(x)
df = pd.DataFrame({'x':x, 'y':y})
df.plot('x', 'y', kind='scatter')
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