[英]numpy, how do I find total rows in a 2D array and total column in a 1D array
Hi apologies for the newbie question, but I'm wondering if someone can help me with two questions. 您对新手问题表示歉意,但我想知道是否有人可以帮我解决两个问题。 Example say I have this,
例子说我有这个,
[[1,2,3],[10,2,2]] [[1,2,3],[10,2,2]]
I have two questions. 我有两个问题。
thank you very much. 非常感谢你。 A
一种
Getting number of rows and columns is as simple as: 获取行数和列数非常简单:
>>> import numpy as np
>>> a=np.array([[1,2,3],[10,2,2]])
>>> num_rows, num_cols = a.shape
>>> print num_rows, num_cols
2 3
import numpy as np
a = np.array([[1,2,3],[10,2,2]])
num_rows = np.shape(a)[0]
num_columns = np.shape(a)[1]
>>> import numpy as np
>>> a=np.array([[1,2,3],[10,2,2]])
>>> a
array([[ 1, 2, 3],
[10, 2, 2]])
#Mean of rows.
>>> np.mean(a,axis=1)
array([ 2. , 4.66666667])
#Mean of columns.
>>> np.mean(a,axis=0)
array([ 5.5, 2. , 2.5])
You can also do this with sum: 你也可以用sum来做到这一点:
#Sum of rows.
>>> np.sum(a,axis=1)
array([ 6, 14])
#Sum of columns
>>> np.sum(a,axis=0)
array([11, 4, 5])
Numpy's function will usually take an axis
argument, in terms of a 2D array axis=0
will apply the function across columns while axis=1
will apply this across rows. Numpy的函数通常采用
axis
参数,就2D数组而言, axis=0
将跨列应用函数,而axis=1
将跨行应用此函数。
>>> import numpy as np
>>> a=np.array([[1,2,3],[10,2,2]])
>>> row_count = len(a[:])
>>> col_count = len(a[:][0])
>>> print ("Row_Count:%d Col_Count:%d " %(row_count,col_count))
Row_Count:2 Col_Count:3
So, if you have n-dimension array you can find all dimensions , but you just need to append [0]
subsequently. 因此,如果你有n维数组,你可以找到所有维度,但你只需要随后附加
[0]
。
There are multiple ways of doing this, one of them is as below: 有多种方法可以做到这一点,其中一种方法如下:
import numpy as np
a = np.array([[1,2],[10,20],[30,20]])
# Total Rows:
np.shape(a)[0]
#Total Columns:
np.shape(a)[1]
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