Error in Stata: add new variable in Mata
One example
of error in Mata is when executing spgen
command, i.e. creating
spatially lagged variables. In this case, variable name is netwealth_riil_hhadj_avg
spgen netwealth_riil_hhadj_avg, lon(longitude)
lat(latitude) swm(bin) dist(200) dunit(km)
will give error
as below.
splag1_netwealth_riil_hhadj_avg_b invalid name
st_addvar(): 3300 argument out of range
calcsplag(): - function returned error
<istmt>: - function returned error
This error
must be read in a reversed order (traceback log), i.e. from bottom to top.
The problem
is when we type the command (the <istmt>), it called the calcsplag(), and calcsplag() called st_addvar(). At this point, it went wrong.
The wrong thing
occurs when Mata want to execute st_addvar().
From the Mata
manual reference, the st_addvar()refers to Mata’s attempt to add new variable in an existing dataset.
Attempt to
create a new variable splag1_netwealth_riil_hhadj_avg_b is unsuccessful. Mata recognized
this name as invalid.
Then, by looking at Mata manual reference regarding variable
naming procedure, Mata accepts variable name between 1-32 characters. On the other hands, the new
variable splag1_netwealth_riil_hhadj_avg_b contains 33 characters.
The
solution is rename with the shorter character length, or duplicate the variable
and naming it with a shortened name.
rename netwealth_riil_hhadj_avg nw_a
or
. gen nw_a = netwealth_riil_hhadj_avg
(6,785 missing values generated)
Then execute
spgen command
. spgen nw_a, lon(longitude) lat(latitude) swm(bin)
dist(200) dunit(km) nostd
Size of spatial weight matrix: 284
Calculating bilateral distance...
Calculating spatial weight matrix...
Distance by Vincenty formula (unit: km)
splag1_nw_a_b is generated in the dataset.
Source:
(Thomas Soseco)
