The Programmer's Solution to the Import/Export Wizard

Transcription

1 The Programmer's Solution to the Import/Export Wizard Lora D. Delwiche, University of California, Davis, CA Susan J. Slaughter, SAS Consultant, Davis, CA Abstract Do you like what the Import/Export Wizard does for you, but you are not really a GUI person? If the answer is yes, then there is good news for you. Version 7 of the SAS System has two new procedures: IMPORT and EXPORT. The IMPORT procedure can read your CSV and tab delimhed files, and if you have SAS/ACCESS to PC File Formats licensed, you can also read dbase, Excel, and Lotus files. The IMPORT procedure also supports Microsoft Access databases. The EXPORT procedure does the opposhe of IMPORT, converting your SAS data sets into other file types. No more clicking your way through window after window, now you can import and export data with just one or two lines of good oldfashioned SAS code. Introduction There are many new features in Version 7 of the SAS system, but one that will warm the hearts of every programmer, are the IMPORT and EXPORT procedures. The Import and Export Wizards, which perform the same functions as the IMPORT and EXPORT procedures, were first available in release 6.12 of SAS. The Wizards are Graphical User Interfaces for importing and exporting delimhed files as well as several popular database formats (if you have SAS/ACCESS to PC File Formats). The problem whh the Wizards is that you can't put them in a SAS program. Now with Version 7, you can write just a few lines of SAS code to read or write delimited or database files. Unfortunately the IMPORT and EXPORT procedures (as well as the Import and Export Wizards) are only available for Windows, 05/2, UNIX, and VMS operating environments. Using IMPORT for reading delimited files Delimited files are raw data files that have a defined character that separates data values: typically spaces, commas or tab characters. Because most software applicaitons can create delimited files, it is useful to learn how to read delimited files into SAS. Delimited files can be tricky to read using just a DATA step, because they often have features that cannot be read using the default SAS settings. The IMPORT procedure easily reads many types of delimited files, doing much of the work for you. IMPORT will scan your data file and automatically determine the variable types (character or numeric), will assign proper lengths to the character variables, and can recognize some date formats. IMPORT will treat two consecutive delimiters in your data file as a missing value, will read values enclosed by quotes, and assign missing values to variables when it runs out of data on a line. Also, if you want, you can use the first line in your data file for the variable names. The IMPORT procedure actually writes a OAT A step for you and after you submit your program, you can look in the log window to see the DATA step it produced. The simplest form of the IMPORT procedure is: PROC IMPORT DATAFILE= 'your-filename' OUT=data-set; where the file you want to read follows the DATAFILE= option and the name of the SAS data set you want to create follows the OUT= option. SAS will determine the file type by the extension of the file as shown in table 1. Table 1. Data file types, extensions, and identifiers for delimited files for PROC IMPORT. Type of Ale Comma delimited Tab delimited Delimiters other than commas and tabs Extension Identifier.csv csv.txt TAB DLM If your file does not have the proper extension, or your file is of type DLM, then you must use the = option to the PROC IMPORT statement. Another option that you might need is REPLACE. If you already have a SAS data set with the name you specified in the OUT= option, then IMPORT will not overwrite it. If you want to overwrhe H, then use the REPLACE option. The following shows both the REPLACE and the options: PROC IMPORT DATAFILE= your-t'ilename' OUT= data-set =identit'ier The IMPORT procedure will, by default, get variable names from the first line in your data file. If the first line in your data files does not have variable names, or you don't want to read them, then add the GETNAMES=NO; statement after the PROC IMPORT statement. Then IMPORT will assign the variables the names VAR1, VAR2, VAR3, and so on. Also if your data file is type DLM, IMPORT assumes that the delimher is a space. If you have a delimiter other than a space, then specify it in 92

2 the DELIMITER= statement. The following shows all the options and statements that pertain to reading delimited files: PROC IMPORT DATAFILE='your-file-name' OUT=dataset-name =DLM GETNAMES=NO; DELIMITER=" delimiter-character'; Example Table 2 shows an example of a comma separated values (CSV) file. The file gives information about several tourist attractions: country, state or province, name of the attraction, adult price, currency, and the date the information was last updated. The first line of the file has labels that can be used for variable names (remember that in Version 7 variable names can be up to 32 characters). The file has some missing data in the Price field (indicated by two consecutive commas), one value for Attraction that is enclosed in quotes because it has an embedded comma, and it has a date field, Updated. The following program reads the data file using the first data line for the variable names and creates a SAS data set named TOURISTSPOTS. Note that it takes only one program statement to read the file. The results of the PROC PRINT can be found in table 3. PROC IMPORT PATAFILE='c:\MyRawData\WUSS9Sin.csv' PROC PRINT; RUN; OUT=touristspots TITLE 'Tourist Attractions'; Notice that, in addition to correctly identifying variable types and lengths, IMPORT also assigns a date informal and format to the variable Updated. The variable's names are taken from the first line in the data file. For fields that have spaces in the variable names, SAS inserts an underscore, so that the variable still conforms to the default rules for variable names. Table 2. CSV data file Country,State or Province,Attraction,Price,Currency,Updated USA,Hawaii,Waikiki Aquarium,6,Dollars,07/ll/98 USA,Hawaii,Polynesian cultural Center,75,Dollars,07/ll/98 USA,Hawaii,Punaluu Black Sand Beach,O,Dollars,07/11/98 USA,Hawaii,Hawaii Volcanoes National Park,O,Dollars,07/ll/98 USA,Hawaii,Koko Crater Botanical Garden,O,Dollars,07/11/98 Belgium,Brussel,Royal Army Museum,O,BEF,03/06/97 Belgium,Brussel,"Atomium,Mini-Europe,soo,BEF,03/06/97 Belgium,Luxembourg,Bastonge American Memorial,245,BEF,03/06/97 Belgium,Liege,Caves of Remouchamps,290,BEF,03/06/97 Belgium,Brabant,Grottes De Folx-les-caves,,BEF,03/06/97 Table 3. SAS data set created from a CSV file State_or_ Tourist Attractions Obs Country Province Attraction Price currency 1 USA Hawaii Waikiki Aquarium 6 Dollars 2 USA Hawaii Polynesian Cultural center 75 Dollars 3USA Hawaii Punaluu Black Sand Beach o Dollars 4 USA Hawaii Hawaii Volcanoes National Park 0 Dollars 5 USA Hawaii Koko Crater Botanical Garden o Dollars 6 Belgium Brussel Royal Army Museum 0 BEF 7 Belgium Brussel Atomium,Uini-Europe 500 BEF 8 Belgium Luxembourg Bastonge American Memorial 245 BEF 9 Belgiu Liege Caves of Remouchamps 290 BEF 10 Belgium Brabant Grottes De Folx-les-Caves BEF Updated 93

3 The following is the SAS log from this program. Notice that IMPORT writes a DATA step where it assigns lengths to character variables, and informats and formats. 1 OPTIONS NODATE LINESIZE=100; 2 PROC IMPORT DATAFILE='c:\MyRawData\WUSS98in.csv' 3 OUT=touristspots 4 PROC PRINT; 5 /*********************************************** *********************** 6 PRODUCT: SAS 7 VERSION: CREATOR: External File Interface - Version DATE: 28JUL98 10 DESC: Generated SAS Datastep Code 11 TEMPLATE SOURCE: (None Specified.) 12 ************************************************ ***********************! data WORK.TOURISTSPOTS %let _EFIERR_ = 0; /* clear ERROR detection macro variable*/ infile 'd:\temp\lora\wuss98in.csv' delimiter=',' MISSOVER DSD lrecl=32767 firstobs=2 ; format Country $9. ; format State_or_Province $12. format Attraction $35. format Price best12. ; format Currency $7. ; format Updated mmddyy10. informat Country $9. ; input informat State_or_Province $12. informat Attraction $35. informat Price best32. ; informat currency $7. ; informat Updated mmddyy10. Country $ State_or_Province $ Attraction $ Price Currency $ Updated If _ERROR_ then!* ERROR detection */ 37 call symput('_efierr_',1); 38 run; RECFM=V,LRECL=32767 NOTE: 10 records were read from the infile c:\myrawdata\wuss98in.csv'. The minimum record length was 45. The maximum record length was 60. NOTE: The data set WORK.TOURISTSPOTS has 10 observations and 6 variables. NOTE: DATA statement used: real time 3.52 seconds 10 rows created in WORK.TOURISTSPOTS from c:\myrawdata\wuss98in.csv. NOTE: WORK.TOURISTSPOTS was successfully created. NOTE: PROCEDURE IMPORT used: real time seconds 39 TITLE 'Tourist Attractions'; 40 RUN; NOTE: PROCEDURE PRINT used: real time 2.51 seconds Using IMPORT for reading database files If you have SAS/ACCESS for the PC File Formats installed on your computer, then you can use IMPORT to read data from several popular PC applications. The general form of the IMPORT procedure for reading database files is the same as for reading delimited files: PROC IMPORT DATAFILE='your-filename' OUT=daea-see; where the file you want to read follows the DATAFILE= option and the name of the SAS data set you want to create follows the OUT= option. SAS will determine the file type by the extension of the file. Table 4 gives the extensions and their corresponding files types and identifiers for dbase, Lotus and Excel files. ' NOTE: Numeric values have been converted to character values at the places given by: (Line): (Column). 37:31 NOTE: The infile c:\myrawdata\wuss98in.csv' is: File Name=c:\MyRawData\WUSS98in.csv, 94

4 Table 4. Data file types, extensions, and identifiers for database and spreadsheet files for PROC IMPORT. Type of File Extension Identifier Excel4 or 5.xis EXCEL Excel97 EXCEL97 Lotus Files. wk1,.wk3, WK1,.wk4 WK3,WK4 dbase. dbf DBF If your file does not have the proper extension, or if you have an Excel 97 file, then you must use the = option to the PROC IMPORT statement. In addition, you may want to use the REPLACE option if you want SAS to write over SAS data sets with the same name as specified in the OUT= option. For example, if you wanted to read an Excel 97 file named Restaurants.xls in the MyRawData directory on the C drive (Windows, OS/2), and you wanted to replace any existing SAS data sets named BESTRESTAURANTS, then you could use the following statement: PROC IMPORT DATAFILE='C:\MYRawData\Restaurants.xls' OUT=bestrestaurants =EXCEL97 As with delimited files, IMPORT will get the variable names from the first row of a spreadsheet. If you do not want IMPORT to do this, then add the GETNAMES=NO optional statement (The GETNAMES= statement is not valid for dbase files.): PROC IMPORT DATAFILE='C:\MyRawData\Restaurants.xls' OUT:bestrestaurants =EXCEL97 GETNAMES=NO; There are additional optional statements in PROC IMPORT that give you control over which spreadsheet to read (for files that contain multiple spreadsheets) as well as the range of cells within a spreadsheet. Also, it is possible to read tables such as Microsoft Access. These features of IMPORT are not covered in this paper. Please refer to the online documentation for version 7 of the SAS software for more information about these features. Using EXPORT for creating delimited files The EXPORT procedure does basically the opposite of the IMPORT procedure. With EXPORT you can convert your SAS data sets into delimited files. The general form of PROC EXPORT for creating delimited fhes is: PROC EXPORT DATA = data-set OUTFILE = 'filename'; where data-set is the SAS data set you are reading, and filename is the name you make up for the output data file. For example, the following statement tells SAS to read a data set named HOTELS and write a comma-delimited file named Hotels.csv in the a directory named MyRawData on the C drive (Windows, OS/2). PROC EXPORT DATA = hotels OUTFILE = c:\myrawdata\hotels.csv'; SAS uses the last part of the file-name, also called the file extension, to decide what type of file to create. You can also specify the file type by adding the = option. Table 5 shows the file-name extensions and identifiers currently available with Base SAS. Table 5. Data file types, extensions, and identifiers for delimited files in PROC EXPORT. Type of file Extension Identifier Comma.csv csv Separated Values Tab-delimited file.txt TAB Space-delimited DLM file Notice that for space-delimited files, there is no standard extension so you must use the = option. The REPLACE option tells SAS that it is ok to replace any existing file with the same name. The following statement, containing the = option, tells SAS to create a space-delimited file named Hotels.spc and to replace any other file with that name. PROC EXPORT DATA = hotels OUTFILE = 'c:\myrawdata\hotels.spc' = DLM If you want to use a delimiter other than tabs, spaces, or commas, then add the DELIMITER= statement. For example, to place a pound sign (#)between data values, use: PROC EXPORT DATA = hotels OUTFILE = 'c:\myrawdata\hotels.spc' = DLM DELIMITER= '#'; Using EXPORT for creating database files If you have SAS/ACCESS to PC File Formats, you can also export database and spreadsheet files. The general form for this is the same as for delimited files: PROC EXPORT DATA = data-set OUTFILE = 'filename REPLACE =identifier; Use the REPLACE option only if you want to allow EXPORT to overwrite existing files with the same name. As with creating delimited files, if you do not include the = option, EXPORT determines the file type by the 95

5 extension of the file you specify. Table 6 shows the extensions and their identifiers. Table 6. Data file types, extensions, and identifiers for spreadsheet and database files in PROC EXPORT. Type of File Extension Excel 5.xis Excel 4 Excel97 Lotus Files dbase Example.wkl,.wk3,.wk4.dbf Identifier EXCEL EXCEL4 EXCEL97 WK1, WK3, WK4 DBF The foilowing program takes the SAS data set, TOURISTSPOTS, created in the first example (using IMPORT to read a CSV file), and creates an Excel 5 file. PROC EXPORT DATA = touristspots OUTFILE = 'C:\MyRawData\WUSS98out.xls' RUN; =EXCEL The following is the SAS log from the above program: NOTE: NOTE: NOTE: PROC EXPORT DATA = touristspots OUTFILE = 'c:\myrawdata\wuss98out.xls' =EXCEL Load completed. Examine statistics below. Inserted (10) obs into WUSS98out.xls. Rejected (0) insert attempts see the log for details. NOTE: c:\myrawdata\wuss98out.xls was successfully created. NOTE: PROCEDURE EXPORT used: 96 RUN; real time 4.73 seconds You can see from the notes, that 10 observations were inserted into the Excel spreadsheet. Figure 1 shows what the spreadsheet looks Hke when you open it into Excel. Notice that the variable names appear in the first row of the spreadsheet. Figure 1. Excel spreadsheet created from a SAS data set using PROC EXPORT 96

6 Conclusions When you want to import or export data, and need the steps included in a SAS program, Version 7 of the SAS software gives you two powerful procedures: IMPORT and EXPORT. You can import delimited files into SAS data sets, and export SAS data sets to delimited files. And, if you have SAS/ACCESS to PC Rle Formats, you can also import and export many popular database formats as well. References Delwiche, Lora D. and Susan J. Slaughter (In Print). The Little SAS Book: A Primer, Second Edition. SAS Institute, Cary, NC. SAS OnlineDoc, Version 7 (1998). SAS Institute, Cary, NC. About the Authors Lora Delwiche and Susan Slaughter are also the authors of The Little SAS Book: A Primer and The Little SAS Book: A Primer. Second Edition. Published at SAS Institute, and may be contacted at: Lora D. Delwiche Information Technology/ANSA University of California, Davis Davis, CA (530) llddelwiche@ucdavis.edu Susan J. Slaughter susanj@ mother.com SAS, and SAS/ACCESS are registered trademarks of SAS Institute Inc. in the USA and other countries. Indicates USA registration. 97