Errors in running code in vignettes:
when running code in 'oc.Rnw'

> library(oc)
Loading required package: pscl
Classes and Methods for R developed in the
Political Science Computational Laboratory
Department of Political Science
Stanford University
Simon Jackman
hurdle and zeroinfl functions by Achim Zeileis

## Optimal Classification Ideal Point Package
## Copyright 2007 -2021
## Keith Poole, Jeffrey Lewis, James Lo, and Royce Carroll
## Support provided by the U.S. National Science Foundation
## NSF Grant SES-0611974


> data(sen90)

> sen90
Source:		 C:/sen90kh.ord 
Number of Legislators:	 102 
Number of Votes:	 596 

Using the following codes to represent roll call votes:
Yea:		 1 2 3 
Nay:		 4 5 6 
Abstentions:	 7 8 9 
Not In Legislature:	 0 

Legislator-specific variables:
[1] "state"      "icpsrState" "cd"         "icpsrLegis" "party"     
[6] "partyCode" 
Detailed information is available via the summary function.

> selector <- c(21, 22, 44, 45, 46, 47, 48, 49, 50, 
+     53, 54, 55, 56, 58, 59, 60, 61, 62, 65, 66, 67, 68, 69, 70, 
+     71, 72, 73, 74, 75, 77,  .... [TRUNCATED] 

> sen90$m <- length(selector)

> sen90$votes <- sen90$votes[, selector]

> rownames(sen90$votes)[1:12]
 [1] "JOHNSON (D USA)"  "SPARKMAN (D AL)"  "HILL (D AL)"      "GRUENING (D AK)" 
 [5] "BARTLETT (D AK)"  "HAYDEN (D AZ)"    "FANNIN (R AZ)"    "FULBRIGHT (D AR)"
 [9] "MCCLELLAN (D AR)" "KUCHEL (R CA)"    "MURPHY (R CA)"    "DOMINICK (R CO)" 

> result <- oc(sen90, polarity = c(2, 5))

Preparing to run Optimal Classification...

	Checking data...

		... 1 of 102 total members dropped.

		Votes dropped:
		... 36 of 208 total votes dropped.

	Running Optimal Classification...

		Generating Start Coordinates...
		Running Edith Algorithm...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...
		Getting normal vectors...
		Getting legislator coordinates...


Optimal Classification completed successfully.
Optimal Classification took 3.42 seconds to execute.


> summary(result)


SUMMARY OF OPTIMAL CLASSIFICATION OBJECT
----------------------------

Number of Legislators:	 101 (1 legislators deleted)
Number of Votes:	 172 (36 votes deleted)
Number of Dimensions:	 2
Predicted Yeas:		 6846 of 7732 (88.5%) predictions correct
Predicted Nays:		 6737 of 7570 (89%) predictions correct

The first 10 legislator estimates are:
                 coord1D coord2D
JOHNSON (D USA)   -0.334  -0.810
SPARKMAN (D AL)    0.220   0.692
HILL (D AL)        0.430   0.702
GRUENING (D AK)   -0.498   0.610
BARTLETT (D AK)   -0.543   0.478
HAYDEN (D AZ)      0.149   0.665
FANNIN (R AZ)      0.616  -0.260
FULBRIGHT (D AR)   0.080   0.956
MCCLELLAN (D AR)   0.490   0.292
KUCHEL (R CA)     -0.112  -0.489

> plot(result)

  When sourcing 'oc.R':
Error: formal argument "at" matched by multiple actual arguments
Execution halted

  'oc.Rnw'... failed