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[面经题目讨论] 10Day retention 设计题

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发表于 2-4-2015 02:13 PM | 显示全部楼层 |阅读模式

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本帖最后由 Sophia 于 2-4-2015 08:24 PM 编辑 1 p( a+ S8 H; W. x& Z% [& a% G/ Q6 A
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10Day retention.
5 p) ^) _. m0 pWe define 10Day UI retention as the percent of users who re-open the app exactly 10 days after the date of their first app open.2 T3 G" `; `2 i3 }# _
Note that whether a user re-opens the app on Day 9 or Day 11 doesn't count. 1 A& q0 ]0 K+ u0 O* q  R: Q7 t/ x
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For example, we were looking to measure over the first two days of January.
; |% G2 o/ `' e# I9 {9 ?3 M30 users opened the app for the first time on Jan.1, and on Jan.11, six of these 30 users re-opened the app.  
2 E5 f/ H( j5 U6 F# lOn Jan.2, 4 users opened the app for the first time, and 3 of these users re-opened the UI on Jan. 12.
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Jan 1Jan2Jan11Jan12
First open304
Re-open63

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* A5 x. @  ?% ^4 [0 w5 gso 10Day- retention from Jan.1 to Jan.2 would then be (6+3) / (30+44) = 12%   (假设保留整数百分比)5 G: m& y9 t4 o, K1 o( h

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数据源:
. y, k" `6 r. e. H; _a JSON  file from a subset of users who began using the app in July. " ^6 N' o$ ~. l6 v
The fields provided are:
& u) {2 J2 H8 L6 V● user_id + J* U3 F% s# U5 X) d1 l
● event_name (假设只有 open app 这一个事件)
& _" v( X2 M! z; J● event_count (count 事件发生了几次)
8 X3 [$ D& M% F9 \4 k9 P' U/ P● event_time (事件发生的时间)
  c  ^+ c* D) G8 M% m3 G7 c$ J$ l● os_name
8 j+ e' Z6 `( R( S, r2 J# R/ M● app_version
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0 h1 B; \' M9 U% Y: Q' }( r9 o0 t现在问题来了.4 _0 C4 l8 ~  c2 K! R' H- Q
1. Design a model for the data that is designed to allow a user to query for 10day retention over a day range,  as well as allow for filtering on a specific OS name and SDK version.
; r( Y8 ?+ |) W2. How would you write a script that reads the data from the file into your model. 2 a' U+ G* N$ z/ p% m& i! I) D& u
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不限语言.. 不过我觉得 java 大法人多... 讨论起来说不定效果好..+ W8 t" T* m/ S

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补充点问题,   用这个 model 你应该能得出以下数据, ~, W- T3 N: L* R: j3 `5 J# F4 k

* s' c7 x% D  dWhat was the overall 10Day Retention over the month of July?. S; Q: g9 `. {8 N: [
What was the 10day Retention from July 8 through July 10 for the ios version?
& i. `  }  C: X( x' ~) aWhat was 10Day Retention over the month of July for iOS7?* b* Q& `7 u* b: z' \8 ?* g& l: ~

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 楼主| 发表于 2-4-2015 09:32 PM | 显示全部楼层
真的假的...一整天了都没人来...

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 楼主| 发表于 2-8-2015 02:57 AM | 显示全部楼层
这帖子太惨...
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