Learning notes of SAS programming and data mining business case 19

Hello everyone , I meet you again , I'm the king of the whole stack , I've prepared for you today Idea Registration code .

continue 《SAS Programming with data Mining business Case study 》 Study note , This paper focuses on data processing practice . contain ：HASH object 、 Define your own format、 And powerful regular expressions

One ：HASH object

Hash Objects are also called hash tables , It is a data structure that can be accessed directly according to the key value . It is a data structure that can be accessed directly according to the key value .

sas Two classes are provided to handle hash tables . Used to store data hash And for traversal hiter,hash Class provides a way to find 、 Join in 、 changes 、 Delete and so on ,hiter Provides for positioning and traversal first、next Other methods .

Strengths ： The key value is searched in memory , It's good for improving performance ;

hash Tables can be executed in data steps , Dynamically add, update or delete observations .

hash The table can locate data very quickly , Reduce the number of searches .

Often used ：

definekey： Define key

Definedata: Definition value

definedone： That's it . Able to load data

add： Add key value . If in hash Table already exists , It ignores ;

replace： Suppose you are alive hash Presence in table , The replacement . If it does not exist, add the key value

remove： Clear key value pair

find： Find health value , If it exists, write the value to the corresponding variable

check： Find key values , If it exists, it returns rc=0, Do not change the value of the current variable ;

output： take hash Table output to dataset

clear： Empty hash surface , But the object is not deleted

equal： Infer two hash Are classes equal

find Demonstration examples of methods ：

libname chapt12 ‘f:\data_model\book_data\chapt12’;

data results;

if _n_=0 then set chapt12.participants;

if _n_ = 1 then do;

declare hash h(dataset:’chapt12.participants’);

h.definekey(‘name’);

h.definedata(‘gender’, ‘treatment’);

h.definedone();

end;

set chapt12.weight;

if h.find() = 0 then

output;

run;

hiter An example of an object ：

data patients;

length patient_id $ 16 discharge 8;

input patient_id discharge:date9.;

datalines;

smith-4123 15mar2004

hagen-2834 23apr2004

smith-2437 15jan2004

flinn-2940 12feb2004

;

data _null_;

if _n_=0 then set patients;

declare hash ht(dataset:”patients”,ordered:”ascending”);

ht.definekey(“patient_id”);

ht.definedata(“patient_id”, “discharge”);

ht.definedone();

declare hiter iter(“ht”);

rc = iter.first();

do while (rc=0);

put patient_id discharge:date9.;

rc = iter.next();

end;

run;

use declare hiter iter(“ht”); to hash surface ht Defines a traverser iter, Then call first Method locates the iterator to hash The first observation of the table , And then use next Methods through hash All records in the table and output .

Business practice – Merging of two data sets ：

data both1(drop=rc);

declare hash plan ();

rc = plan.definekey (‘plan_id’);

rc = plan.definedata (‘plan_desc’);

rc = plan.definedone ();

do until (eof1) ;

set chapt12.plans end = eof1;

rc = plan.add ();

end;

do until (eof2) ;

set chapt12.members end = eof2;

call missing(plan_desc);

rc = plan.find ();

output;

end;

stop;

run;

The above procedure can be simplified to ：

data both2;

length plan_id 3 plan_desc 20;

if _n_ = 1 then do;

declare hash h(dataset:’chapt12.plans’);

h.definekey(‘plan_id’);

h.definedata(‘plan_desc’);

h.definedone();

call missing(plan_desc);

end;

set chapt12.members;

rc=h.find();

run;

Two ：format

Define your own format：

Proc Format;

Value $ Sex_Fmt

‘F’=’ Woman ‘

‘M’=’ male ‘

Other = ‘ Unknown ‘;

Value Age_Dur

Low-10=”10 Under the age of “

11-13=”11-13 year “

14-<15=”14-15″

15-High=”15 Years of age or older “;

Run;

application ：

Data test;

Set sashelp.class(keep=sex age);

x=put(sex,$sex_fmt);y=put(age,age_dur.);

Run;

3、 ... and ： Regular expressions ：

/…/ The beginning and end of a regular expression .

| Choice between several items ,“ or ” operation ;

() Match group , Mark the beginning and end of a subexpression .

. Random characters other than line breaks .

\w Any word character , Numbers, upper and lower case letters, and underscores

\W Any non word character

\s Any white space character , Include spaces 、 tabs 、 A newline 、 A carriage return 、 Chinese full corner space, etc ;

\S Any non white space character ,

\d 0-9 Any number

\D Any non numeric character

[…]

[^…]

[a-z] from a To z

[^a-z] Not from a To z Random characters in the range

^ Match the starting position of the input string

$ Matches the end of the input string

\b Describe the front or back boundaries of narrative words

\B Indicates a non word boundary

* matching 0 Times or times

+ Match once or more

? Match zero times or once

{n} matching n Time

{n,} matching n More than once

{n,m} matching n To m Time

Functions are often used ：

Prxparse Define a regular expression

Prxmatch Return the first matching position of the matching pattern

Call prxsubstr Returns the starting position and length of the matching pattern in the target string

Prxposn Returns the matching pattern value corresponding to the regular expression sub expression

Call prxposn Returns the corresponding matching pattern and length of the regular expression sub expression

Cal l prxnext Returns multiple matching positions and lengths of the matching pattern in the target string

Prxchange Replace the value of the matching pattern

Call prxchange Replace the value of the matching pattern

eg1：

data _null_;

if _n_ = 1 then pattern_num = rxparse(“/cat/”);

retain pattern_num;

input string $30.;

position = rxmatch(pattern_num,string);

file print;

put pattern_num= string= position=;

datalines;

there is a cat in this line.

does not match cat

cat in the beginning

at the end, a cat

cat

;

run;

eg2： data validation

data match_phone;

set chapt12.phone_numbers;

if _n_ = 1 then pattern = prxparse(“/\(\d\d\d\) ?

\d\d\d-\d{4}/”);

retain pattern;

if prxmatch(pattern,phone) gt 0 then output;

run;

Find out the mismatched mobile phone number

data unmatch_phone;

set chapt12.phone_numbers;

where not prxmatch(“/\(\d\d\d\) ?

\d\d\d-\d{4}/”,phone);

run;

Eg3: Extract a string that matches a pattern

data extract;

if _n_ = 1 then do;

pattern = prxparse(“/\(\d\d\d\) ?

\d\d\d-\d{4}/”);

if missing(pattern) then do;

put “error in compiling regular expression”;

stop;

end;

end;

retain pattern;

length number $ 15;

input string $char80.;

call prxsubstr(pattern,string,start,length);

if start gt 0 then do;

number = substr (string,start,length);

number = compress(number,” “);

output;

end;

keep number;

datalines;

this line does not have any phone numbers on it

this line does: [phone] la di la di la

also valid [phone]

two numbers here [phone] and [phone]

;

run;

eg4： Pick up the name

data ReversedNames;

input name & $32.;

datalines;

Jones, Fred

Kavich, Kate

Turley, Ron

Dulix, Yolanda

;

data FirstLastNames;

length first last $ 16;

keep first last;

retain re;

if _N_ = 1 then

re = prxparse(‘/(\w+), (\w+)/’);

set ReversedNames;

if prxmatch(re, name) then

do;

last = prxposn(re, 1, name);

first = prxposn(re, 2, name);

end;

run;

notes ：1,2 Each represents two groups in the regular expression

eg5： Extract qualified names

data old;

input name $60.;

datalines;

Judith S Reaveley

Ralph F. Morgan

Jess Ennis

Carol Echols

Kelly Hansen Huff

Judith

Nick

Jones

;

data new;

length first middle last $ 40;

re1 = prxparse(‘/(\S+)\s+([^\s]+\s+)?(\S+)/o’);

re2 = prxparse(‘/(\S+)(\s+)([^\s]+\s+)(?)(\S+)/o’);

set old;

id1=prxmatch(re1, name);

id2=prxmatch(re2, name);

if id1 then

do;

first = prxposn(re1, 1, name);

middle = prxposn(re1, 2, name);

last = prxposn(re1, 3, name);

end;

if id2 then test=prxposn(re1, 4, name);

put test=;

run;

Eg6: Return multiple locations of the matching pattern

data _null_;

expressionid = prxparse(‘/[crb]at/’);

text = ‘the woods have a bat, cat, and a rat!’;

start = 1;

stop = length(text);

call prxnext(expressionid, start, stop, text, position, length);

do while (position > 0);

found = substr(text, position, length);

put found= position= length=;

call prxnext(expressionid, start, stop, text, position, length);

end;

run;

notes ： First run call prxnext Return to one position, Then enter the cycle , In extracting substrings that meet the conditions . Run again all prxnext, The next matching position;

Eg7: replace text

data cat_and_mouse;

input text $char40.;

length new_text $ 80;

if _n_ = 1 then match = prxparse(“s/[Cc]at/mouse/”);

retain match;

call prxchange(match,-1,text,new_text,len,trunc,num);

if trunc then put “note: new_text was truncated”;

datalines;

the Cat in the hat

there are two cat cats in this line

here is no replacement

;

run;

Copyright notice ： This article is an original blog article . Blog , Without consent , Shall not be reproduced .

Publisher ： Full stack programmer stack length , Reprint please indicate the source ：https://javaforall.cn/117664.html Link to the original text ：https://javaforall.cn