Uploaded Numpy tutorial file

Author: joeyajames

Diff for: numpy_tutorial.txt

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+import numpy as np
+
+pip install numpy
+pip install numpy --upgrade
+
+import numpy as np
+
+a = np.array([2,3,4])
+
+a = np.arange(1, 12, 2)		# (from, to, step)
+
+a = np.linspace(1, 12, 6)	# (first, last, num_elements) float data type
+
+a.reshape(3,2)
+a = a.reshape(3,2)
+
+a.size
+
+a.shape
+
+a.dtype
+
+a.itemsize
+
+# this works:
+b = np.array([(1.5,2,3), (4,5,6)])
+
+# but this does not work:
+b = np.array(1,2,3)		# square brackets are required
+
+a < 4						# prints True/False
+
+a * 3					# multiplies each element by 3
+a *= 3					# saves result to a
+
+a = np.zeros((3,4))
+
+a = np.ones((2,3))
+
+a = np.array([2,3,4], dtype=np.int16)
+
+a = np.random.random((2,3))
+
+np.set_printoptions(precision=2, suppress=True)		# show 2 decimal places, suppress scientific notation
+
+a = np.random.randint(0,10,5)
+a.sum()
+a.min()
+a.max()
+a.mean()
+a.var()		# variance
+a.std()		# standard deviation
+
+
+a.sum(axis=1)
+a.min(axis=0)
+
+a.argmin()		# index of min element
+a.argmax()		# index of max element
+a.argsort()		# returns array of indices that would put the array in sorted order
+a.sort()		# in place sort
+
+# indexing, slicing, iterating
+a = np.arange(10)**2
+a[2]
+a[2:5]
+
+for i in a:
+	print (i ** 2)
+a[::-1]		# reverses array
+
+for i in a.flat:
+	print (i)
+
+	
+a.transpose()
+
+a.ravel()			# flattens to 1D
+
+# read in csv data file
+data = np.loadtxt("data.txt", dtype=np.uint8, delimiter=",", skiprows=1 )
+# loadtxt does not handle missing values. to handle such exceptions use genfromtxt instead.
+
+data = np.loadtxt("data.txt", dtype=np.uint8, delimiter=",", skiprows=1, usecols=[0,1,2,3])
+
+np.random.shuffle(a)
+
+a = np.random.random(5)
+
+np.random.choice(a)
+
+np.random.random_integers(5,10,2)	# (low, high inclusive, size)
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