How do I make Order Book Depth Chart in Matplotlib?

Question:

I am trying to create a "Depth Chart" from the Order book which will look like the below:

enter image description here

I figured out that histogram will be used but unable to set the proper bins hence producing an improper chart. 'ASK/QTY' are given below:

[49579.41, 49580.66, 49581.39, 49585.42, 49585.43, 49586.99, 49588.0, 49588.74, 49589.62, 49589.8, 49589.81, 49590.0, 49590.37, 49590.38, 49591.38, 49591.87, 49592.84, 49593.32, 49593.86, 49594.17, 49594.36, 49595.32, 49595.54, 49595.92, 49595.97, 49596.87, 49596.88, 49596.99, 49597.06, 49597.2, 49597.21, 49597.52, 49597.64, 49597.79, 49598.08, 49598.46, 49598.69, 49598.98, 49599.52, 49600.0, 49600.14, 49600.26, 49600.34, 49600.47, 49600.62, 49600.73, 49601.0, 49601.25, 49601.3, 49601.71, 49601.85, 49601.93, 49602.2, 49602.7, 49602.93, 49603.12, 49603.15, 49603.23, 49603.56, 49604.27, 49604.31, 49604.32, 49604.89, 49604.9, 49605.12, 49605.21, 49605.5, 49605.59, 49606.0, 49606.13, 49606.39, 49606.62, 49607.2, 49607.5, 49607.68, 49607.69, 49607.71, 49607.76, 49608.05, 49608.11, 49608.67, 49609.71, 49610.0, 49610.07, 49610.18, 49610.53, 49610.54, 49611.72, 49612.1, 49612.25, 49612.42, 49612.71, 49612.99, 49613.0, 49613.42, 49613.45, 49613.53, 49613.62, 49613.84, 49613.92]
[4.514622, 1.0, 1.0, 0.014002, 0.04, 0.012384, 0.005441, 0.04, 0.254507, 0.219849, 0.559163, 0.14, 0.219849, 0.02, 0.010085, 0.399503, 0.50407, 0.05, 0.133538, 0.000952, 0.03, 0.023, 0.1205, 0.063524, 0.038323, 0.371299, 0.03, 0.041181, 0.182644, 0.088, 0.022, 0.040338, 0.137032, 0.464753, 0.05, 0.893, 1.248, 0.022, 0.3, 4.683597, 0.797, 0.004717, 0.504112, 0.009785, 0.03, 0.006436, 0.005641, 0.2937, 0.116174, 0.0183, 0.853, 0.041181, 0.03, 0.005512, 0.4, 0.24, 0.040373, 0.364929, 0.008, 0.005515, 0.163396, 0.03, 0.00377, 0.03943, 0.02386, 0.765352, 0.46, 0.115285, 0.251659, 0.049, 0.111, 0.4, 0.4, 0.364734, 0.022, 0.319989, 0.141003, 0.426611, 0.022, 0.06, 0.626486, 0.5, 0.004243, 0.059612, 0.3, 4.747239, 0.04, 0.2406, 0.021046, 0.237078, 0.428943, 0.000626, 0.000932, 0.001094, 1.906807, 0.03, 0.349154, 0.040366, 0.004549, 0.038309]

My code is given below:

import matplotlib
from utilities import get_order_book
import matplotlib.pyplot as plt

if __name__ == '__main__':
    pair = 'BTC/USDT'
    asks, bids = get_order_book(pair)
    ask_x = []
    ask_y = []
    for ask in asks:
        ask_x.append(ask[0])
        ask_y.append(ask[1])

    print(ask_x)
    print(ask_y)
    plt.bar(ask_x, ask_y, 2)
    plt.hist(ask_x, bins=len(ask_x))
    plt.show()
Asked By: Volatil3

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Answers:

If you are not interested in coloring the area under the curve, you can use matplotlib.pyplot.step (pay attention to where parameter, in this case I used the default pre value):

x = [49579.41, 49580.66, 49581.39, 49585.42, 49585.43, 49586.99, 49588.0, 49588.74, 49589.62, 49589.8, 49589.81, 49590.0, 49590.37, 49590.38, 49591.38, 49591.87, 49592.84, 49593.32, 49593.86, 49594.17, 49594.36, 49595.32, 49595.54, 49595.92, 49595.97, 49596.87, 49596.88, 49596.99, 49597.06, 49597.2, 49597.21, 49597.52, 49597.64, 49597.79, 49598.08, 49598.46, 49598.69, 49598.98, 49599.52, 49600.0, 49600.14, 49600.26, 49600.34, 49600.47, 49600.62, 49600.73, 49601.0, 49601.25, 49601.3, 49601.71, 49601.85, 49601.93, 49602.2, 49602.7, 49602.93, 49603.12, 49603.15, 49603.23, 49603.56, 49604.27, 49604.31, 49604.32, 49604.89, 49604.9, 49605.12, 49605.21, 49605.5, 49605.59, 49606.0, 49606.13, 49606.39, 49606.62, 49607.2, 49607.5, 49607.68, 49607.69, 49607.71, 49607.76, 49608.05, 49608.11, 49608.67, 49609.71, 49610.0, 49610.07, 49610.18, 49610.53, 49610.54, 49611.72, 49612.1, 49612.25, 49612.42, 49612.71, 49612.99, 49613.0, 49613.42, 49613.45, 49613.53, 49613.62, 49613.84, 49613.92]
y = [4.514622, 1.0, 1.0, 0.014002, 0.04, 0.012384, 0.005441, 0.04, 0.254507, 0.219849, 0.559163, 0.14, 0.219849, 0.02, 0.010085, 0.399503, 0.50407, 0.05, 0.133538, 0.000952, 0.03, 0.023, 0.1205, 0.063524, 0.038323, 0.371299, 0.03, 0.041181, 0.182644, 0.088, 0.022, 0.040338, 0.137032, 0.464753, 0.05, 0.893, 1.248, 0.022, 0.3, 4.683597, 0.797, 0.004717, 0.504112, 0.009785, 0.03, 0.006436, 0.005641, 0.2937, 0.116174, 0.0183, 0.853, 0.041181, 0.03, 0.005512, 0.4, 0.24, 0.040373, 0.364929, 0.008, 0.005515, 0.163396, 0.03, 0.00377, 0.03943, 0.02386, 0.765352, 0.46, 0.115285, 0.251659, 0.049, 0.111, 0.4, 0.4, 0.364734, 0.022, 0.319989, 0.141003, 0.426611, 0.022, 0.06, 0.626486, 0.5, 0.004243, 0.059612, 0.3, 4.747239, 0.04, 0.2406, 0.021046, 0.237078, 0.428943, 0.000626, 0.000932, 0.001094, 1.906807, 0.03, 0.349154, 0.040366, 0.004549, 0.038309]


fig, ax = plt.subplots()

ax.step(x, y)

plt.show()

enter image description here

Otherwise, if you want to color the area under the curve, you can use matplotlib.pyplot.stairs, as already suggested by BigBen in the comment. Pay attention to the fact you need to add a value to x array, because this time it represents edges, not data points.

x.append(x[-1])

fig, ax = plt.subplots()

ax.stairs(edges = x, values = y, fill = True)

plt.show()

enter image description here

It seems the two plots are different: this because in matplotlib.pyplot.step I used the default value for where parameter; on the contrary, matplotlib.pyplot.stairs uses a post interpolation:

x.append(x[-1])

fig, ax = plt.subplots()

ax.step(x[:-1], y, where = 'post')
ax.stairs(edges = x, values = y, fill = True)

plt.show()

enter image description here

Answered By: Zephyr

The accepted answer gets you part of the way there, but an actual depth chart is monotonically decreasing/increasing for bids/asks because it includes a cumulative summation of the limit orders. The rationale is that the depth chart will show you "how many units are available for a given price or better" :

For example, say you have the following bids for TKR:

Price Quantity
$10 3
$5 4
$3 10

If you place a sell order TKR at $5, then you will be able to sell 7 units at that price; 4 will be bought at $5, and 3 (which were willing to be bought at $10) will definitely be bought at the more appealing $5. Therefore, the depth chart at Price=5 should show a quantity of 7, not 4. Likewise, at Price=3, the quantity would be 17.

Going back to your question/example, the easiest way that I’ve found (all credit goes to this notebook/article) would be to leverage seaborn’s ecdfplot as follows:

import random
import pandas as pd
import matplotlib.pyplot as plt
import seaborn as sns

# your original data
ask_price = [49579.41, 49580.66, 49581.39, 49585.42, 49585.43, 49586.99, 49588.0, 49588.74, 49589.62, 49589.8, 49589.81, 49590.0, 49590.37, 49590.38, 49591.38, 49591.87, 49592.84, 49593.32, 49593.86, 49594.17, 49594.36, 49595.32, 49595.54, 49595.92, 49595.97, 49596.87, 49596.88, 49596.99, 49597.06, 49597.2, 49597.21, 49597.52, 49597.64, 49597.79, 49598.08, 49598.46, 49598.69, 49598.98, 49599.52, 49600.0, 49600.14, 49600.26, 49600.34, 49600.47, 49600.62, 49600.73, 49601.0, 49601.25, 49601.3, 49601.71, 49601.85, 49601.93, 49602.2, 49602.7, 49602.93, 49603.12, 49603.15, 49603.23, 49603.56, 49604.27, 49604.31, 49604.32, 49604.89, 49604.9, 49605.12, 49605.21, 49605.5, 49605.59, 49606.0, 49606.13, 49606.39, 49606.62, 49607.2, 49607.5, 49607.68, 49607.69, 49607.71, 49607.76, 49608.05, 49608.11, 49608.67, 49609.71, 49610.0, 49610.07, 49610.18, 49610.53, 49610.54, 49611.72, 49612.1, 49612.25, 49612.42, 49612.71, 49612.99, 49613.0, 49613.42, 49613.45, 49613.53, 49613.62, 49613.84, 49613.92]
ask_qty = [4.514622, 1.0, 1.0, 0.014002, 0.04, 0.012384, 0.005441, 0.04, 0.254507, 0.219849, 0.559163, 0.14, 0.219849, 0.02, 0.010085, 0.399503, 0.50407, 0.05, 0.133538, 0.000952, 0.03, 0.023, 0.1205, 0.063524, 0.038323, 0.371299, 0.03, 0.041181, 0.182644, 0.088, 0.022, 0.040338, 0.137032, 0.464753, 0.05, 0.893, 1.248, 0.022, 0.3, 4.683597, 0.797, 0.004717, 0.504112, 0.009785, 0.03, 0.006436, 0.005641, 0.2937, 0.116174, 0.0183, 0.853, 0.041181, 0.03, 0.005512, 0.4, 0.24, 0.040373, 0.364929, 0.008, 0.005515, 0.163396, 0.03, 0.00377, 0.03943, 0.02386, 0.765352, 0.46, 0.115285, 0.251659, 0.049, 0.111, 0.4, 0.4, 0.364734, 0.022, 0.319989, 0.141003, 0.426611, 0.022, 0.06, 0.626486, 0.5, 0.004243, 0.059612, 0.3, 4.747239, 0.04, 0.2406, 0.021046, 0.237078, 0.428943, 0.000626, 0.000932, 0.001094, 1.906807, 0.03, 0.349154, 0.040366, 0.004549, 0.038309]
# generate fake bid data for illustration purposes
bid_price = [p-(0.001*p) for p in ask_price]
bid_qty = [q*(2*random.random()) for q in ask_qty]

ask_df = pd.DataFrame({'price': ask_price, 'quantity': ask_qty})
bid_df = pd.DataFrame({'price': bid_price, 'quantity': bid_qty})

fig, ax = plt.subplots()
ax.set_title(f"Order Book Depth Chart")
sns.ecdfplot(x="price", weights="quantity", stat="count",
             data=ask_df, ax=ax, color="red")
sns.ecdfplot(x="price", weights="quantity", stat="count",
                complementary=True, data=bid_df, ax=ax, color="green")
# complementary=True allows reflects that lower bids are "better"
ax.set_xlabel("Price")
ax.set_ylabel("Quantity")

with the following result:
Order Book Depth Chart

Answered By: Omar A