duplicates

Let's say I have four samples: id=1, 2, 3, and 4, with one or more measurements on each of those samples: > a <- data.frame(id=c(1,1,2,2,3,4), value=c(1,2,3,-4,-5,6)) > a id value 1 1 1 2 1 2 3 2 3 4 2 -4 5 3 -5 6 4 6 I want to remove duplicates, keeping only one entry per ID - the one having the largest absolute value of the "value" column. I.e., this is what I want: > a[c(2,4,5,6), ] id value 2 1 2 4 2 -4 5 3 -5 6 4 6 How might I do this in R? aa <- a[order(a$id, -abs(a$value) ), ] #sort by id and reverse of abs(value) aa[ !duplicated(aa$id), ] # take the first row within each id id value 2

I'm sure this is an extremely obvious question, and that there's a function that does exactly this, but I can't seem to find it. In PHP, I'd like to know if my array has duplicates in it, as efficiently as possible. I don't want to remove them like array_unique does, and I don't particularly want to run array_unique and compare it to the original array to see if they're the same, as this seems very inefficient. As far as performance is concerned, the "expected condition" is that the array has no duplicates. I'd just like to be able to do something like if (no_dupes($array)) // this deals with

I've seen a number of variations on this but nothing quite matches what I'm trying to accomplish. I have a table, TableA , which contain the answers given by users to configurable questionnaires. The columns are member_id, quiz_num, question_num, answer_num . Somehow a few members got their answers submitted twice. So I need to remove the duplicated records, but make sure that one row is left behind. There is no primary column so there could be two or three rows all with the exact same data. Is there a query to remove all the duplicates? Saharsh Shah Add Unique Index on your table: ALTER

I have problem with duplicate key. Long time can`t find answer. Please help me solve this problem or explain why i get duplicate key error. Trace: { [MongoError: E11000 duplicate key error collection: project.monitor index: _id_ dup key: { : 24392490 }] name: 'MongoError', message: 'E11000 duplicate key error collection: project.monitor index: _id_ dup key: { : 24392490 }', driver: true, index: 0, code: 11000, errmsg: 'E11000 duplicate key error collection: project.monitor index: _id_ dup key: { : 24392490 }' } at /home/project/app/lib/monitor.js:67:12 at callback (/home/project/app/node

I'm trying to add a library to my project, right now my current build.gradle is: apply plugin: 'com.android.application' android { compileSdkVersion 21 buildToolsVersion "21.1.2" repositories { mavenCentral() } defaultConfig { applicationId "com.example.guycohen.cheaters" minSdkVersion 11 targetSdkVersion 21 versionCode 1 versionName "1.0" // Enabling multidex support. multiDexEnabled true } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } } dependencies { compile fileTree(dir: 'libs', include: ['*.jar']) compile

I have a table in my database which has duplicate records that I want to delete. I don't want to create a new table with distinct entries for this. What I want is to delete duplicate entries from the existing table without the creation of any new table. Is there any way to do this? id action L1_name L1_data L2_name L2_data L3_name L3_data L4_name L4_data L5_name L5_data L6_name L6_data L7_name L7_data L8_name L8_data L9_name L9_data L10_name L10_data L11_name L11_data L12_name L12_data L13_name L13_data L14_name L14_data L15_name L15_data see these all are my fields : id is unique for every