英文:
Perform parallel calculations on tables and concatenate the results into one table
问题
我想在DolphinDB中对多个内存表执行并行计算，然后将结果连接到一个表中。
例如，我想创建一个UDF来对表t0执行计算，其中涉及if-else语句：
- 条件为真：返回t0
- 条件为假：返回NULL值
最后，我希望将所有结果连接到一个表中。有人可以帮我编写一个脚本吗？提前感谢。
这里是一个伪代码示例：
def work(){
t0=table(1 2 3 as a, `x`y`z as b, 10.8 7.6 3.5 as c);
if(bad_cond){return NULL}
else{return t0}
}
ploop(work)
英文:
I want to perform parallel calculations on several in-memory tables in DolphinDB and concatenate the results into one table.
For example, I want to create a UDF to perform calculations on a table t0, which involves a if-else statement:
- the condition is true: return t0
- the condition is false: return NULL values
At last, I wish to concatenate all the results into one table. Can anyone help me to write a script? Thanks in advance.
Here is a pseudocode for you:
def work(){
t0=table(1 2 3 as a, `x`y`z as b, 10.8 7.6 3.5 as c);
if(bad_cond){return NULL}
else{return t0}
}
ploop(work)
答案1
得分: 1
参考以下脚本：
def work(p):
if p == 1:
return table(1 2 3 as id)
else:
return NULL
}
loop(work, 1 2 1).unionAll(false)
在这里，loop 返回一个包含子作业结果的元组，然后将输出表传递给 unionAll 进行连接。
英文:
Refer to the following script:
def work(p){
if(p==1) return table(1 2 3 as id)
else return NULL
}
loop(work, 1 2 1).unionAll(false)
Here, loop returns a tuple containing the results of sub-jobs, and then the output tables are passed to unionAll to be concatenated.
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