# Convolution in Python

Learn how to perform convolution between two signals in Python.

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In [1]:

```
import plotly.plotly as py
import plotly.graph_objs as go
import plotly.figure_factory as ff
import numpy as np
import pandas as pd
import scipy
from scipy import signal
```

#### Import DataÂ¶

Let us import some stock data to apply convolution on.

In [2]:

```
stock_data = pd.read_csv('https://raw.githubusercontent.com/plotly/datasets/master/stockdata.csv')
df = stock_data[0:15]
table = ff.create_table(df)
py.iplot(table, filename='stockdata-peak-fitting')
```

Out[2]:

#### Convolve Two SignalsÂ¶

`Convolution`

is a type of transform that takes two functions `f`

and `g`

and produces another function via an integration. In particular, the convolution $(f*g)(t)$ is defined as:

We can use convolution in the discrete case between two n-dimensional arrays.

In [11]:

```
sample = range(15)
saw = signal.sawtooth(t=sample)
data_sample = list(stock_data['SBUX'][0:100])
data_sample2 = list(stock_data['AAPL'][0:100])
x = list(range(len(data_sample)))
y_convolve = signal.convolve(saw, data_sample2)
x_convolve = list(range(len(y_convolve)))
trace1 = go.Scatter(
x = x,
y = data_sample,
mode = 'lines',
name = 'SBUX'
)
trace2 = go.Scatter(
x = x,
y = data_sample2,
mode = 'lines',
name = 'AAPL'
)
trace3 = go.Scatter(
x = x_convolve,
y = y_convolve,
mode = 'lines',
name = 'Convolution'
)
data = [trace1, trace2, trace3]
py.iplot(data, filename='convolution-of-two-signals')
```

Out[11]: