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a = 1 + 2
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a
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a + 1
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_
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? sum
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! ps -xa | grep python
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import time
%time time.sleep(1)
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import numpy as np
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np.array([[1,2,3], [7,1,2]])
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data = np.array([1,2,3,4,5])
data
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data[1:-2]
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data + 1
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data * 2
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data * data
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np.sum(data * data)
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data.dot(data)
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data > 2
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data[data > 2]
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replaces = data[:]
replaces[data > 2] = -1
replaces
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matrix = np.random.rand(5, 4)
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matrix
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matrix[1]
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matrix[:, 1]
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matrix[(1, 2), :]
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import random
vec_len = 1000
v1 = [random.random() for _ in range(vec_len)]
v2 = [random.random() for _ in range(vec_len)]
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%timeit [a * b for a, b in zip(v1, v2)]
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np_v1, np_v2 = np.array(v1), np.array(v2)
%timeit np_v1 * np_v2
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np.arange(1, 5, 0.7)
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np.linspace(1, 5, 13)
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first = np.array([[1, 2], [3, 4]])
second = np.array([[10, 20], [30, 40]])
np.hstack((first, second))
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np.vstack((first, second))
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import pandas as pd
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df = pd.read_csv('iris.csv')
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df.head(3)
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df[['Sepal.length', 'Petal.length']].head(5)
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df[df['Sepal.length'] > 7.5]
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df.describe()
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%pylab inline
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df['Sepal.length'].plot(kind='hist');
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import matplotlib.pyplot as plt
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x = np.arange(1, 10, 0.2)
y = np.sin(x)
plt.plot(x, y);
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plt.scatter(x, y);
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plt.plot(x, y, marker='o');