[英]Matlab using accumarray with cell array
I am quite new to Matlab, but I have some experience with other programming languages. 我是Matlab的新手,但我对其他编程语言有一些经验。 I have a very large table imported from MySQL in Matlab.
我在Matlab中从MySQL导入了一个非常大的表。 It is given as cell array that looks something like this:
它作为单元格数组给出,如下所示:
date key sales weight name
12/11 101 1200 20 blue
12/11 178 1200 70 purple
13/11 209 1300 15 purple
12/11 101 1200 10 blue
14/11 678 1200 10 yellow
12/11 340 1500 30 green
17/11 178 1900 50 purple
And I want the output to be this: 我希望输出是这样的:
key sales weight name
101 2400 30 blue
178 3100 120 purple
209 1300 15 purple
678 1200 10 yellow
340 1500 30 green
So I would like to combine the rows which have the same number in the column 'key'. 所以我想在'key'列中组合具有相同编号的行。 Meanwhile I would like to sum the column 'sales' and 'weight' and keep the column 'name' (each 'key' has the same 'name', but each 'name' can have multiple 'keys')
同时我想将“销售”和“重量”这一列加在一起,并保留“名称”栏目(每个“键”具有相同的“名称”,但每个“名称”可以有多个“键”)
I know this is possible with a for loop, but as I am having to manipulate a lot of tables in similar but different ways this is computational intensive. 我知道这可能是一个for循环,但由于我不得不以类似但不同的方式操作很多表,这是计算密集型的。
I have read in similar problems this can be solved using accumarray, but can this be done with accumarray with a sub as cell array? 我已经阅读了类似的问题,这可以使用accumarray来解决,但是这可以通过使用sub作为单元阵列的accumarray来完成吗? And how would that look like?
那会是怎样的样子?
Here is one method using accumarray
, however it might be worth your while to consider the new table data structure instead of a cell matrix (I'm sure you can easily convert to it) 这是使用
accumarray
一种方法,但是考虑新的表数据结构而不是单元格矩阵可能值得您accumarray
(我确信您可以轻松转换为它)
T = { 101 1200 20 'blue'
178 1200 70 'purple'
209 1300 15 'purple'
101 1200 10 'blue'
678 1200 10 'yellow'
340 1500 30 'green'
178 1900 50 'purple'};
[u, ind, x] = unique([T{:,1}])
key = T(ind,1)
sales = accumarray(x', [T{:,2}])
weight = accumarray(x', [T{:,3}])
name = T(ind,4)
[key, num2cell(sales), num2cell(weight), name]
x={ '12/11' 101 1200 20 'blue'
'12/11' 178 1200 70 'purple'
'13/11' 209 1300 15 'purple'
'12/11' 101 1200 10 'blue'
'14/11' 678 1200 10 'yellow'
'12/11' 340 1500 30 'green'
'17/11' 178 1900 50 'purple'};
[~,b,c]=unique([x{:,2}]);
y=[x(b,2),...
num2cell(sparse(1,c,[x{:,3}]))',...
num2cell(sparse(1,c,[x{:,4}]))',...
x(b,[5])];
unique
is used to get the indices of duplicate keys. unique
用于获取重复键的索引。 sparse
is used to get the sum. sparse
用于得到总和。
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