How Can You Efficiently Remove Multiple Rows from a List by ID?

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SUMMARY

The discussion focuses on efficiently removing multiple rows from a list by their IDs using a loop. The user initially attempts to drop rows in a forward manner, which causes ID changes due to the shifting indices. A solution is proposed to drop rows starting from the end of the list, ensuring that the IDs remain consistent throughout the process. This method effectively prevents index shifting issues and allows for the successful removal of specified rows.

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raymound
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hi
I have a list which I want to drop some of it's rows
and I have the id of the rows I want to drop in a list and there's no algorythem in the list

how can I do that?
I know the Command Drop[MC, {id}] whould drop the row number id but if I put this in a loop and try to drop them one by one the id's whould change since I'm dropping some rows and I tried to figure a way out of it but the just didn't work, any help?

the first one in my list and the second one the id of the rows to be dropped

PHP:
{{0.00414938, 6.}, {0.00438052, 5.9}, {0.00460842, 5.8}, {0.00482298, 
  5.7}, {0.0050097, 5.6}, {0.00515407, 5.5}, {0.00517174, 
  5.4}, {0.00504864, 5.3}, {0.00469823, 5.2}, {0.00402235, 
  5.1}, {0.0029449, 5.}, {0.00165498, 4.9}, {-0.00110326, 
  4.8}, {-0.00556929, 4.7}, {-0.0113029, 4.6}, {-0.0183193, 
  4.5}, {-0.0258924, 4.4}, {-0.0363815, 4.3}, {-0.0540341, 
  4.2}, {-0.0762913, 4.1}, {-0.0978172, 4.}, {-0.120518, 
  3.9}, {-0.15479, 3.8}, {-0.188365, 3.7}, {-0.221846, 
  3.6}, {-0.250625, 3.5}, {-0.283568, 3.4}, {-0.276114, 
  3.3}, {-0.227546, 3.2}, {-0.129161, 3.1}, {0.0897719, 
  3.}, {0.511911, 2.9}, {1.19876, 2.8}, {2.32358, 2.7}, {4.16475, 
  2.6}, {7.02193, 2.5}, {11.4346, 2.4}, {18.2226, 2.3}, {28.5117, 
  2.2}, {44.0589, 2.1}, {67.3399, 2.}, {"", ""}}

PHP:
{2, 3, 4, 5, 7, 8, 9, 10, 12, 13, 14, 15, 17, 18, 19, 20, 22, 24, 26,
28, 30, 32, 34, 36, 38, 40}
 
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raymound said:
if I put this in a loop and try to drop them one by one the id's would change since I'm dropping some rows

What if your loop drops them one by one starting with the end of your list instead of the beginning?

First drop row 40 and then drop row 38 and then drop row 36 ... and then drop row 2.

The number of rows remaining in your list would decrease with each iteration, but by doing this in reverse order of the id's that you still need to delete would not change.
 

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