Reading Other Text Data Formats - Infile and Infix

Infile - Space Delimited Data
Infix - Fixed Width Data
Data Dictionaries

Infile

infile (free format) may be useful if you have downloaded a data file from the web and it conforms to these specifications:

The file should NOT have variables names on the first line.
Character variables that have spaces in them, such as full names, must be enclosed in quotes.
Numbers can have commas and minus signs, but not dollar or percent signs.
infile assumes that the variables have spaces between them and that there are no blank spaces where it expects data (missing numeric data need to be represented by something, either a number or a single period, '.').

The command to read a file with infile is:

. infile var1 var2 var3 using mydata.txt Essentially, insheet assumes that commas separate the variables, and infile assumes that blanks separate the variables. It may be easier, though, to bring a file into Excel first, save it as a csv, then use insheet.

There is another form of infile (fixed format) that is used with a "dictionary" file to read certain data files with complex formats. See below.

infix

A fixed-width text file has no "delimiter" (divider) characters. Instead, variable values are placed in the same "columns" (places on the page) for each line of data. Here's an example of how data containing variables for individuals' name, age, and weight would look in a fixed-width text file (fixed-width text files will not have a line for the variable names):

John Smith 42250 Mary Johnson 66120 Margaret Veryverylonglastnamed29110

Note that the data are all packed together. The blanks between the names and ages of the first two people are called "filler". They are there for two reasons: one, to leave room for people with longer names (like our third person), and two, to force each value of each variable to occupy the same columns. In this example, we would say that the variable "name" is in columns 1-30, "age" is in columns 31-32, and "weight" is in columns 33-35. Assuming it was named "mydata.txt", the command to read this file with infix would be:

. infix str name 1-30 age 31-32 weight 33-35 using mydata.txt Note that "name" is a string (text) variable, while the other two variables are numeric. You tell Stata that a variable is a string by placing "str" in front of its name. Otherwise Stata assumes that the variable is numeric. The infix command can read files with longer lines of data in an analogous way. Simply list as many variables and columns as you have.

Dictionary files

Stata dictionary files can vary in their complexity but all of them basically specify which data file to read, where the variables are located in the file and what they are to be called. It is rare that you will really need to use a dictionary file—in most cases, including the example below, an infix statement will work just as well and is simpler to write. We present this basic information on dictionary files mainly so you will be familiar with them in case you are using data for which the producer provided one.

Optionally, labels can also be provided in the dictionary file. Once the dictionary file is written, it is accessed by issuing the Stata infile command:

     . infile using [dictionary_file]

where dictionary_file is the name of your Stata dictionary file.

In this example, the raw data are saved in a file named "latimes.raw" and the dictionary file is saved in a different file named "latimes.dct." To read the data, you would call the dictionary file:

     infile using latimes.dct

Given below is a sample Stata dictionary file:

     dictionary using latimes {
     _column(13)  wght     %5f  "Weight Value"
     _column(22)  groups   %1f  "Ethnic/racial grp"
     _column(23)  rdir     %1f  "Cntry in right dir.?"
     _column(24)  apbush   %1f  "Do You app. of Bush?"
     _column(27)  rvote    %1f  "Are you reg. to vote?"
     _column(28)  wvote    %1f  "Vote for/Lean toward?"
     _column(29)  whyvote  %1f  "Why  this candidate?"
     _newline
     _column(48)  location %1f "Area you live in?"
     _column(49)  views    %1f  "Views on political matters?"
     _column(50)  tparty   %1f  "Party views?"
     _column(52)  relign   %1f  "What religion?"
     _column(55)  faminc   %1f  "Family income"
     _column(66)  agerng   %1f  "Age range"
     _column(69)  educ     %1f  "Education"
     _newline
     }

The above dictionary starts with the words dictionary using , which defines the file as a Stata dictionary. The name of the file which contains the actual data appears immediately following the word using . In this example, the data file is named "latimes.raw" and the name latimes appears in the dictionary file. The data file extension is assumed to be .raw unless a different file extension is specifically provided.

The actual data dictionary is enclosed within curly brackets ({ }). On each line of the dictionary, the _column command is used to move the pointer to the location where the data item starts. After the column locator is the variable name. After the variable name is the format with which the data item is to be read (see the Stata manual for possible formats). After the format, a quoted text string can be provided for a variable label. If there is more than one line of data for each record, a _newline command must be given to advance the pointer to the next line in the data file.

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