Pythonデータ処理ノート——numpy編(一)
キーワード:基礎データ入力方式、データ選択方式
import numpy as np
#np
np.array(object)
#object array_like, list,range
#[1,2,3] list;range(3) range
# np.array([1,2,3]) np.array(range(3)) numpy.ndarray
------
>>>np.array([1,2,3])
array([1,2,3])
>>>print(np.array([1,2,3]))
[1 2 3]
#
------
np.arange([start,]stop,[step,]dtype = None)
# ndarray
# range , 、 、 , array
------
>>>np.arange(1,7,2)
array([1,3,5])
------
np.linspace(start,stop,num = 50)
# ndarray
# , , (num )
np.loadtxt(path)
# txt,csv,dat
# ndarray
#
# ————
data = np.arange(7)
# data[start:stop:step,]
# list
------
>>>data[1:6:2]
array([1,3,5])
>>>data[::-1][::2]
array([6,4,2,0])
------
# ————
data = np.array([[1,2,3],
[4,5,6],
[7,8,9]])
# data[row,column]
# row column , (row column) ","
------
>>>data[:,: ]#data
array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
>>>data[0,:]# ( )
array([1, 2, 3])
>>>data[1,1:]#
array([5, 6])
>>>data[0,0]# , numpy.int64
1
------
data = np.arange(24).reshape(2,3,4)# array, floor,row,column
data = array([[[ 0, 1, 2, 3],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11]],
[[12, 13, 14, 15],
[16, 17, 18, 19],
[20, 21, 22, 23]]])
>>>data[:,:,:]# data
>>>data[0,:,:]# data[0], floor
array([[ 0, 1, 2, 3],
[ 4, 5, 6, 7],
[ 8, 9, 10, 11]])
>>>data[:,1,:]# floor
array([[ 4, 5, 6, 7],
[16, 17, 18, 19]])
>>>data[:,:,1]# floor
array([[ 1, 5, 9],
[13, 17, 21]])