# NamedHist¶

Nino-hist provides a customized histogram object named NamedHist for boost-histogram. The new feature of NamedHist is to fill the axes with their names in the random order. Let’s see how it works in Nino-hist NamedHist.

Supposed that you have installed Nino-hist, you can created a NamedHist object like this. If you want to change the hist packaging path (for example, using as sub-project), you can go to the setup.cfg and modify [options.packages.find] in it.

Now, let’s flip two coins.

[1]:

import hist
import numpy as np
import matplotlib.pyplot as plt

h = hist.NamedHist(
hist.axis.Bool(name='USD', title='usd font'),
hist.axis.Bool(name='EUR', title='eur font')
)
usd = np.random.rand(1_000_000) > 0.5
eur = np.random.rand(1_000_000) > 0.5

h.fill(USD=usd, EUR=eur)

bar = [h[0, 0], h[0, 1], h[1, 0], h[1, 1]]
x = range(len(bar))
bar_color = ['steelblue', 'indianred', 'violet', 'orange']
fig, ax = plt.subplots(figsize=(8,5))
ax.bar(x, bar, color=bar_color)
plt.xticks(x, ("usd+, eur+", "usd+, eur-", "usd-, eur+",\
"usd-, eur-"), size=16)
plt.ylabel("Counts", size=16)
fig.show()


Shown in the figure above, the four possibilities would have almost same counts when generating seeds randomly.

NamedHist is simple and friendly to newers. In NamedHist, we do not have to follow the order of axes initialization, to remember their names is just ok. Let’s see another example of NamedHist.

[2]:

import boost_histogram as bh
import hist
import numpy as np
import matplotlib.pyplot as plt

h = hist.NamedHist(
hist.axis.Regular(50, -3, 3, name="x"),
hist.axis.Regular(50, -3, 3, name="y"),
)

x = np.random.randn(1_000_000)
y = np.random.randn(1_000_000)
h.fill(y=y, x=x)

fig, ax = plt.subplots(figsize=(8,5))
w, x, y = h.to_numpy()
mesh = ax.pcolormesh(x, y, w.T, cmap='autumn')
ax.set_xlabel('x')
ax.set_ylabel('y')
fig.colorbar(mesh)
fig.show()


You can also use names to get and set items like this.

[3]:

import boost_histogram as bh
import hist
import numpy as np
import matplotlib.pyplot as plt

h = hist.NamedHist(
hist.axis.Regular(100, -1, 1, name="X"),
hist.axis.Regular(100, -1, 1, name="Y"),
hist.axis.Bool(name="V"),
)

x, y = np.random.random_sample([2, 1_000_000])*2 - 1
valid = np.abs(x)**2 + (y + .2 - np.power(np.abs(x), 2/3))**2 < .5
h.fill(Y=y, X=x, V=valid)

valid_only = h[{'V':bh.loc(True)}]   # this will cause dimentionality reduction
# valid_and_invalid = h[{'V':slice(None, None, bh.sum)}]
fig, ax = plt.subplots(figsize=(8,5))
W, X, Y = valid_only.to_numpy()
mesh = ax.pcolormesh(X, Y, W.T, cmap='autumn')
ax.set_xlabel('X')
ax.set_ylabel('Y')
fig.colorbar(mesh)
fig.show()


As you can see, name is a import property for NamedHist like the id of axes. You can assign the names to the axes in your histogram and use it to fill, to get item, etc. Have a try by yourself!