index : 字符函数 数值函数 日期含糊 SCL函数 特殊函数
/**********************字符函数******************************/
Compress(<source><,chars><,modifiers>);
功能：消除或保留指定的字符
I or i: ignores the case of the characters to be kept or removed
k or K:keeps the characters in the list instead of removing them*消除指定的空格或字符串;
data compress1; x1 = " 1 2 3 a"; x2 = "Abacabbad";
y1 = compress(x1," ");
y = compress(x1); *作用y1的一样，消除空格，tab，暂时已知的两个; y2 = compress(x2,"Ab");*消除所有A或b的字符;
put y1 y2; run;
i 和 k的用法
data me; x = "123-102-212"; y3 = compress(x,"0123456789", 'k'); y4 = compress(x,'-'); run;
SUBSTR( matrix, position <, length> )
功能：截取子字符串
matrix is a character matrix or quoted literal
position is a numeric matrix or scalar that contains the starting position
length is a numeric matrix or scalar that contains the length of the substring
当其位于等号左边或右边时，含义有区别
右边是的情况，为给变量赋值 date='06MAY98'; month=substr(date,3,3); year=substr(date,6,2); put @1 month @5 year; 结果为MAY 98 左边时的情况，为改变字符串中子字符串的值 a='KIDNAP'; substr(a,1,3)='CAT'; put a; 结果为CATNAP
默认情况下，如果不写长度，则会从起始位置一直截取到字符串的末尾
a='KIDNAP';
y = substr(a,2);
结果为IDNAP
source:identifies the constant, variable, or expression whose value you want to reformat. The source argument can be character or numeric
format:contains the SAS format that you want applied to the value that is specified in the source
将数值型或字符型转化为字符型
data a; x = "01jan2007"d; *x是数字型，表示为17167，如果不对其输出格式做规定，则输出为数值; format x date11.; *将其转化为日期格式01-JAN-2007; y = put(x,date11.);*将x通过put函数转化为字符型; z = compress(y,'-');*通过compress函数去除'-',compress中的变量要为字符型,如果直接compress(x)达不到想要的效果; run;
name=transtrn(name, "Mrs.", "Ms."); name=transtrn(name, "Miss", "Ms."); put name; 结果为Mrs. Joan Smith Ms. Joan Smith 结果为Miss Alice Cooper Ms. Alice Cooper
除去连续的两个字符，而不是将两个字符中的任意一个都在字符串中全部清除，可以考虑同transtrn代替compress data a; x = 'abasdsab'; y = transtrn(x,'ab',''); run;
LENGTH( matrix ) ;
功能：计算字符串的长度
说明：The length of a string is equal to the position of the rightmost nonblank character in the string. If a string is entirely blank, its length value is set to 1.
中文：所计算的长度是从第一个子都到字符串最右端的一个非空字符为止，如果字符串为空，则长度设为1
c = {"Hello" "My name is Jenny "}; b = length(c); print b; b = 5 16
比较全的字符函数的实例
/********************************数值函数*******************************/
a = '20071011'; y = input(a,yymmdd10.); format y yymmdd10.;
日期也为数值型
功能：向下取整取间隔时间，不到一个月按一个月计算，按此换算
interval:specifies a character constant, a variable, or an expression that contains an interval name(interval name有很多种，具体见sas帮助文档)
start-date:specifies a SAS expression that represents the starting SAS date, time, or datetime value.
end-date:specifies a SAS expression that represents the ending SAS date, time, or datetime value.
method:specifies that intervals are counted using either a discrete or a continuous method.(DISCRETE为默认,CONTINUOUS备选)
data a; interval='month'; start='14FEB2000'd; end='13MAR2000'd; months_default=intck(interval, start, end); months_discrete=intck(interval, start, end,'d'); months_continuous=intck(interval, start, end,'c');*相隔时间大于一个月小于两个月，按一个月计算; output; end='14MAR2000'd; months_default=intck(interval, start, end); months_discrete=intck(interval, start, end,'d'); months_continuous=intck(interval, start, end,'c'); output; start='31JAN2000'd; end='01FEB2000'd; months_default=intck(interval, start, end); months_discrete=intck(interval, start, end,'d'); months_continuous=intck(interval, start, end,'c'); output; format start end date.; run; proc print data=a; run;
2.3：INTNX(custom-interval, start-from, increment <, 'alignment'> )
功能：返回指定时间间隔的日期
前两个参数同上
increment:specifies a negative, positive, or zero integer that represents the number of date, time, or datetime intervals. Increment is the number of intervals to shift the value of start-from.
alignment:controls the position of SAS dates within the interval(Default:BEGINNING,MIDDLE,END,SAME)，是字符型在函数中要打引号。
alignment应用的区别
data a; a = '05jan2007'd; yBegin = intnx('month',a,3,'beginning'); y = intnx('month',a,3); yMiddle = intnx('month',a,3,'middle'); ySame = intnx('month',a,3,'same'); yEnd = intnx('month',a,3,'end'); format a yBegin y yMiddle ySame yEnd date10.; run; proc print data=a noobs;run;
2.4：INT( matrix ) ;
The INT function truncates the decimal portion of the value of the argument
proc iml; y = 2.8; b = int(y); x={12.95 10.9999999999999, -30.5 1e-6}; c = int(x); print b, c; quit;
b=2 x={12,10,-30,0}
/*********************************日期函数********************************/
yactact=yrdif(sdate, edate, 'actual'); *用的较多，暂时记这个，得到的是小数;
int(yactact); *取整，4.x 全部变为4;
round(yactact，.x); *保留到小数点后x位，如果省略第二项则四舍五入;
option yearcutoff=1920; 所以计算的日期都在1920年后的一百年内，所以01/01/01是表示2001年而不是1901年
/*********************************SCL函数********************************/
OPEN(<table-name<>,mode>); 对应CLOSE(data-set-id)返回值和OPEN相反
功能：打开一个数据集，并返回一直独一无二的ID，成功是ID>0，失败时ID=0;
table-name:the SAS table or SAS/ACCESS view descriptor to open, specified as <libref.>member-name<(data-set-options)>. The default value for table-name is _LAST_, which is the last table created in the current SAS session.
mode:不同的访问模式，见sas帮助文档
FETCHOBS(table-id,row-number<,options>);
功能：获取打开数据集的一条观测，成功返回0，否则为非0
VARNUM(table-id,var-name);
功能：contains the position number of the column in the SAS table, or 0 if the column is not in the SAS table
/********************************特殊函数*********************************/
argument:specifies a numeric or character constant, variable, or expression.
n:specifies the number of lagged values.
作用：Storing values at the bottom of the queue and returning values from the top of the queue occurs only when the function is executed(将上一个lag函数作用的数值保存在队列底部，每一次运行都读取队列顶部的)。
data one; input x @@; y=lag1(x); z=lag2(x); datalines; 1 2 3 4 5 6 ;
功能：DIFn is defined as DIFn(x)=x-LAGn(x). 计算当前值与上一个值的差！
data two; input X @@; Z=lag(x); D=dif(x); datalines; 1 2 6 4 7 ; proc print data=two; run;
