Is ~ a valid character in a variable name?

[Daniel Feenberg]

-import delimited- and -insheet- create variable names with a tilde when the name in the first line of the data file too long. But I find that the -generate- command won't allow such names on the right-hand side. I can -rename-, but I would prefer to avoid the extra work. For example here I can -describe- or -rename- a variable, but -generate- thinks it has an "invalid name".:

import delimited using /tmp/Links_2007.txt
(18 vars, 99,999 obs)

. des shareholderbv~d

              storage   display    value
variable name   type    format     label      variable label
-------------------------------------------------------------------------------
shareholderbv~d str19   %19s                  Shareholder BvD ID

. gen x=shareholderbv~d
shareholderbv~d invalid name
r(198);

. rename shareholderbv~d x0

. des x
              storage   display    value
variable name   type    format     label      variable label
-------------------------------------------------------------------------------
x               str19   %19s                  Shareholder BvD ID

Am I overlooking something very simple? Any suggestions?

Daniel Feenberg
NBER

[Eric de Souza]

From the Stata manual: "A name is a sequence of 1 to 32 letters (A–Z, a–z, and any Unicode letter), digits (0–9), and underscores ( )."

[Nick Cox]

-import delimited- and -insheet- create variable names with a tilde when the name in the first line of the data file too long. But I find that the -generate- command won't allow such names on the right-hand side. I can -rename-, but I would prefer to avoid the extra work.

Not so. Rather you can get shown an abbreviated name if the name assigned is uncomfortably long.

The same thing can happen directly with generate:

. clear

. set obs 10
number of observations (_N) was 0, now 10

. gen somethingabsurdlylong = 42

. d

Contains data
  obs:            10                          
 vars:             2                          
 size:            80                          
--------------------------------------------------------------------------------------------------------------------------------------------------
              storage   display    value
variable name   type    format     label      variable label
--------------------------------------------------------------------------------------------------------------------------------------------------
y               float   %9.0g                
somethingabsu~g float   %9.0g                
--------------------------------------------------------------------------------------------------------------------------------------------------
Sorted by:
     Note: Dataset has changed since last saved.

. describe, fullnames

Contains data
  obs:            10                          
 vars:             1                          
 size:            40                          
--------------------------------------------------------------------------------------------------------------------------------------------------
              storage   display    value
variable name   type    format     label      variable label
--------------------------------------------------------------------------------------------------------------------------------------------------
somethingabsurdlylong
                float   %9.0g                
--------------------------------------------------------------------------------------------------------------------------------------------------
Sorted by:
     Note: Dataset has changed since last saved.

[Daniel Feenberg]

The tilde isn't in the data. -import delimited- added it. Am I the only one that doesn't consider it a bug when -import delimited- creates a variable with an invalid name? I suppose it is "by design"?

[Daniel Feenberg]

Ah, now we are getting someplace. The modified name is an abbreviation for the full name, and the abbreviation is acceptable in some places, but not others. The original name had spaces - what happens to them?

[Nick Cox]

Posts are crossing here, but import delimited does nothing wrong on your evidence. The only question arising from #1 is what you can see reported.

Now in #5 there is something new: If the "original name" had spaces, they aren't allowed in Stata variable names and presumably were removed. If the variable label is
Shareholder BvD ID then my guess is that the spaces were removed or replaced with underscores, but the fullnames option in #3 removes any need to guess.

[Daniel Feenberg]

OK, I will rename my variables to something sensible.

Daniel Feenberg

[Daniel Feenberg]

OK, I will rename my variables to something sensible.

Daniel Feenberg

[Nick Cox]

In fact looking at #1 allows the guess

shareholderbvdid for that variable name. If so, it's just one character longer than will fit without abbreviation.