Are conditional footnotes possible?

Question

We are looking to create production Latex tables using xtable in R. Each table will have different footnotes based on certain data in the table.

For example, in the below table instead of manually entering the footnote after NAICS_TITLE, I would want something like (if text="NAICS_TITLE" {footnote=("INDUSTRY")}) Is anything like this possible?

\documentclass{article}

% needed to modify the table margins
\usepackage[top=.5in,bottom=1in,left=.25in,right=.25in]{geometry}

% needed to generate tables longer than 1 page
\usepackage{longtable}

% needed to include footnotes in captions
\usepackage[singlelinecheck=false]{caption}

% endnotes uses so that they display at the end of the table instead of the page
\usepackage{endnotes}
\let\footnote=\endnote

\begin{document}

% Table created by stargazer v.5.2 by Marek Hlavac, Harvard University. E-mail: hlavac at fas.harvard.edu
% Date and time: Thu, Nov 19, 2015 - 11:26:01 AM
\begin{longtable}{@{\extracolsep{-5pt}} llllllll} 
\caption{Incidence rates\protect\footnote{rates footnote} of nonfatal occupational injuries and illnesses by industry and case types, 2014} 
\\[-1.8ex]\hline 
\hline \\[-1.8ex] 
NAICS\_TITLE \footnote{Industry footnote} & OWNERSHIP & TEI\footnote{NAICS footnote} & TRC & CDART & CDAFW\footnote{DAFW footnote} & CDJTR & CORC \\ 
\hline \\[-1.8ex]
All industries including private, state and local\footnote{All industries footnote} & $0$ & 000000 & $3.400$ & $1.800$ & $1.100$ & $0.700$ & $1.600$ \\ 
All private industries & $50$ & 000000 & $3.200$ & $1.700$ & $1$ & $0.700$ & $1.500$ \\ 
   Goods producing & $50$ & GP1AAA & $3.800$ & $2.200$ & $1.100$ & $1$ & $1.700$ \\ 
   Natural resources and mining & $50$ & GP1NRM & $3.800$ & $2.300$ & $1.300$ & $1$ & $1.500$ \\ 
   Agriculture forestry fishing and hunting\footnote{farming footnote} & $50$ & GP2AFH & $5.500$ & $3.300$ & $1.800$ & $1.500$ & $2.200$ \\ 
   Crop production & $50$ & 111000 & $5.500$ & $3.300$ & $1.600$ & $1.700$ & $2.300$ \\ 
   Animal production and aquaculture & $50$ & 112000 & $7.100$ & $4.400$ & $2.500$ & $1.900$ & $2.700$ \\ 
   Forestry and logging & $50$ & 113000 & $5.100$ & $2.100$ & $1.900$ & $0.200$ & $2.900$ \\ 
   Fishing hunting and trapping & $50$ & 114000 & $4.900$ & $4.100$ & $$ & $0.300$ & $0.800$ \\ 
   Agriculture and forestry support activities & $50$ & 115000 & $4.500$ & $2.700$ & $1.400$ & $1.300$ & $1.800$ \\ 
   Mining quarrying and oil and gas extraction\footnote{mining footnote} & $50$ & GP2MIN & $2$ & $1.300$ & $0.800$ & $0.400$ & $0.700$ \\ 
   Oil and gas extraction & $50$ & 211000 & $$ & $0.800$ & $0.600$ & $0.200$ & $0.500$ \\ 
   Mining except oil and gas & $50$ & 212000 & $2.800$ & $1.900$ & $1.400$ & $0.500$ & $0.900$ \\ 
   Support activities for mining & $50$ & 213000 & $1.800$ & $1.100$ & $0.700$ & $0.500$ & $0.700$ \\ 
   Construction & $50$ & GP1CON & $3.600$ & $2$ & $1.300$ & $0.600$ & $1.600$ \\ 
   Construction & $50$ & GP2CON & $3.600$ & $2$ & $1.300$ & $0.600$ & $1.600$ \\ 
   Construction of buildings & $50$ & 236000 & $3.300$ & $1.900$ & $1.300$ & $0.600$ & $1.400$ \\ 
   Heavy and civil engineering construction & $50$ & 237000 & $3$ & $1.700$ & $1.100$ & $0.700$ & $1.300$ \\ 
   Specialty trade contractors & $50$ & 238000 & $3.800$ & $2$ & $1.400$ & $0.600$ & $1.800$ \\ 
   Manufacturing & $50$ & GP1MFG & $4$ & $2.200$ & $1$ & $1.200$ & $1.700$ \\ 
   Manufacturing & $50$ & GP2MFG & $4$ & $2.200$ & $1$ & $1.200$ & $1.700$ \\ 
   Food manufacturing & $50$ & 311000 & $5.100$ & $3.300$ & $1.300$ & $2$ & $1.800$ \\ 
   Beverage and tobacco product manufacturing & $50$ & 312000 & $6$ & $4$ & $1.600$ & $2.300$ & $2$ \\ 
   Textile mills & $50$ & 313000 & $3.200$ & $1.700$ & $0.700$ & $1$ & $1.500$ \\ 
   Textile product mills & $50$ & 314000 & $3.500$ & $2.100$ & $1$ & $1.100$ & $1.400$ \\ 
   Apparel manufacturing & $50$ & 315000 & $1.500$ & $0.800$ & $0.400$ & $0.500$ & $0.700$ \\ 
   Leather and allied product manufacturing & $50$ & 316000 & $3.900$ & $2.200$ & $1$ & $1.100$ & $1.700$ \\ 
   Wood product manufacturing & $50$ & 321000 & $6.800$ & $3.800$ & $1.900$ & $1.800$ & $3$ \\ 
   Paper manufacturing & $50$ & 322000 & $2.900$ & $1.700$ & $0.900$ & $0.900$ & $1.100$ \\ 
   Printing and related support activities & $50$ & 323000 & $2.500$ & $1.500$ & $0.800$ & $0.700$ & $1$ \\ 
   Petroleum and coal products manufacturing & $50$ & 324000 & $1.700$ & $0.800$ & $0.500$ & $0.300$ & $0.900$ \\ 
   Chemical manufacturing & $50$ & 325000 & $2.300$ & $1.400$ & $0.700$ & $0.700$ & $0.900$ \\ 
   Plastics and rubber products manufacturing & $50$ & 326000 & $4.600$ & $2.700$ & $1.300$ & $1.500$ & $1.900$ \\ 
   Nonmetallic mineral product manufacturing & $50$ & 327000 & $5.100$ & $3.200$ & $1.700$ & $1.500$ & $2$ \\ 
   Primary metal manufacturing & $50$ & 331000 & $5.200$ & $2.900$ & $1.200$ & $1.600$ & $2.300$ \\ 
   Fabricated metal product manufacturing & $50$ & 332000 & $4.800$ & $2.400$ & $1.300$ & $1.200$ & $2.400$ \\ 
   Machinery manufacturing & $50$ & 333000 & $3.800$ & $1.900$ & $0.900$ & $1$ & $1.900$ \\ 
   Computer and electronic product manufacturing & $50$ & 334000 & $1.300$ & $0.700$ & $0.400$ & $0.300$ & $0.600$ \\ 
   Electrical equipment and appliance mfg. & $50$ & 335000 & $3$ & $1.800$ & $0.800$ & $1$ & $1.300$ \\ 
   Transportation equipment manufacturing & $50$ & 336000 & $4.700$ & $2.600$ & $1$ & $1.600$ & $2.100$ \\ 
   Furniture and related product manufacturing & $50$ & 337000 & $4.800$ & $2.600$ & $1.200$ & $1.400$ & $2.200$ \\ 
   Miscellaneous manufacturing & $50$ & 339000 & $2.500$ & $1.400$ & $0.700$ & $0.700$ & $1.100$ \\ 
   Service providing & $50$ & SP1AAA & $3$ & $1.600$ & $0.900$ & $0.600$ & $1.400$ \\ 
   Trade transportation and utilities & $50$ & SP1TTU & $3.600$ & $2.200$ & $1.300$ & $1$ & $1.400$ \\ 
   Wholesale trade & $50$ & SP2WHT & $2.900$ & $1.900$ & $1.100$ & $0.900$ & $1$ \\ 
   Merchant wholesalers durable goods & $50$ & 423000 & $2.600$ & $1.600$ & $0.900$ & $0.700$ & $1$ \\ 
   Merchant wholesalers nondurable goods & $50$ & 424000 & $3.900$ & $2.800$ & $1.500$ & $1.300$ & $1.100$ \\ 
   Electronic markets and agents and brokers & $50$ & 425000 & $1.600$ & $1.100$ & $0.700$ & $$ & $0.500$ \\ 
   Retail trade & $50$ & SP2RET & $3.600$ & $2$ & $1$ & $1$ & $1.600$ \\ 
   Motor vehicle and parts dealers & $50$ & 441000 & $3.400$ & $1.700$ & $1$ & $0.700$ & $1.700$ \\ 
   Furniture and home furnishings stores & $50$ & 442000 & $3.900$ & $2.300$ & $1.500$ & $0.800$ & $1.600$ \\ 
   Electronics and appliance stores & $50$ & 443000 & $1.400$ & $0.800$ & $0.600$ & $0.200$ & $0.600$ \\ 
   Building material and garden supply stores & $50$ & 444000 & $5$ & $3.400$ & $1.600$ & $1.800$ & $1.600$ \\ 
   Food and beverage stores & $50$ & 445000 & $4.400$ & $2.600$ & $1.400$ & $1.200$ & $1.700$ \\ 
   Health and personal care stores & $50$ & 446000 & $2.100$ & $0.900$ & $0.600$ & $0.300$ & $1.300$ \\ 
   Gasoline stations & $50$ & 447000 & $2.300$ & $1.100$ & $0.600$ & $0.500$ & $1.200$ \\ 
   Clothing and clothing accessories stores & $50$ & 448000 & $2$ & $0.700$ & $0.400$ & $0.300$ & $1.400$ \\ 
   Sporting goods hobby book and music stores & $50$ & 451000 & $2.600$ & $1.100$ & $0.600$ & $0.500$ & $1.400$ \\ 
   General merchandise stores & $50$ & 452000 & $4.800$ & $2.800$ & $1.200$ & $1.600$ & $2$ \\ 
   Miscellaneous store retailers & $50$ & 453000 & $3.400$ & $1.700$ & $1$ & $0.700$ & $1.700$ \\ 
   Nonstore retailers & $50$ & 454000 & $1.800$ & $1.200$ & $0.600$ & $0.500$ & $0.700$ \\ 
   Transportation and warehousing & $50$ & SP2TRW & $4.800$ & $3.400$ & $2.300$ & $1.200$ & $1.400$ \\ 
   Air transportation & $50$ & 481000 & $7.500$ & $6.100$ & $4.500$ & $1.600$ & $1.300$ \\ 
   Rail transportation & $50$ & 482000 & $2$ & $1.500$ & $1.300$ & $0.100$ & $0.500$ \\ 
   Water transportation & $50$ & 483000 & $2.300$ & $1.400$ & $0.900$ & $0.600$ & $0.900$ \\ 
   Truck transportation & $50$ & 484000 & $4.500$ & $3.200$ & $2.300$ & $0.900$ & $1.300$ \\ 
   Transit and ground passenger transportation & $50$ & 485000 & $4.600$ & $3.200$ & $2.400$ & $0.800$ & $1.400$ \\ 
   Pipeline transportation & $50$ & 486000 & $1.800$ & $0.800$ & $0.600$ & $0.200$ & $0.900$ \\ 
   Scenic and sightseeing transportation & $50$ & 487000 & $3.200$ & $2.400$ & $1.900$ & $0.600$ & $0.800$ \\ 
   Support activities for transportation & $50$ & 488000 & $3.600$ & $2.200$ & $1.500$ & $0.800$ & $1.400$ \\ 
   Couriers and messengers & $50$ & 492000 & $7.100$ & $5.200$ & $3.100$ & $2.200$ & $1.800$ \\ 
   Warehousing and storage & $50$ & 493000 & $5.200$ & $3.700$ & $1.700$ & $1.900$ & $1.500$ \\ 
   Utilities & $50$ & SP2UTL & $2.400$ & $1.300$ & $0.700$ & $0.600$ & $1.200$ \\ 
   Utilities & $50$ & 221000 & $2.400$ & $1.300$ & $0.700$ & $0.600$ & $1.200$ \\ 
   Information & $50$ & SP1INF & $1.400$ & $0.800$ & $0.600$ & $0.200$ & $0.600$ \\ 
   Information & $50$ & SP2INF & $1.400$ & $0.800$ & $0.600$ & $0.200$ & $0.600$ \\ 
   Publishing industries except internet & $50$ & 511000 & $1$ & $0.400$ & $0.300$ & $0.100$ & $0.600$ \\ 
   Motion picture and sound recording industries & $50$ & 512000 & $1.600$ & $0.600$ & $0.400$ & $0.200$ & $1$ \\ 
   Broadcasting except internet & $50$ & 515000 & $1.400$ & $0.600$ & $0.400$ & $0.200$ & $0.700$ \\ 
   Telecommunications & $50$ & 517000 & $2.200$ & $1.600$ & $1.300$ & $0.300$ & $0.600$ \\ 
   Data processing hosting and related services & $50$ & 518000 & $0.500$ & $0.200$ & $0.200$ & $0.100$ & $0.300$ \\ 
   Other information services & $50$ & 519000 & $0.400$ & $0.200$ & $$ & $0$ & $0.200$ \\ 
   Financial activities & $50$ & SP1FIA & $1.200$ & $0.500$ & $0.400$ & $0.200$ & $0.700$ \\ 
   Finance and insurance & $50$ & SP2FIN & $0.700$ & $0.200$ & $0.200$ & $0$ & $0.400$ \\ 
   Monetary authorities - central bank & $50$ & 521000 & $1$ & $0.500$ & $0.300$ & $0.200$ & $0.500$ \\ 
   Credit intermediation and related activities & $50$ & 522000 & $0.800$ & $0.300$ & $0.200$ & $0.100$ & $0.500$ \\ 
   Securities commodity contracts investments & $50$ & 523000 & $0.200$ & $0.100$ & $0.100$ & $0$ & $0.100$ \\ 
   Insurance carriers and related activities & $50$ & 524000 & $0.600$ & $0.200$ & $0.200$ & $0$ & $0.400$ \\ 
   Real estate and rental and leasing & $50$ & SP2RRL & $2.900$ & $1.500$ & $0.900$ & $0.600$ & $1.400$ \\ 
   Real estate & $50$ & 531000 & $2.500$ & $1.300$ & $0.900$ & $0.400$ & $1.200$ \\ 
   Rental and leasing services & $50$ & 532000 & $4$ & $1.900$ & $0.900$ & $1$ & $2.100$ \\ 
   Lessors of nonfinancial intangible assets & $50$ & 533000 & $1$ & $0.200$ & $0.100$ & $$ & $0.800$ \\ 
   Professional and business services & $50$ & SP1PBS & $1.500$ & $0.800$ & $0.500$ & $0.300$ & $0.700$ \\ 
   Professional and technical services & $50$ & SP2PST & $0.900$ & $0.400$ & $0.300$ & $0.100$ & $0.600$ \\ 
   Professional and technical services & $50$ & 541000 & $0.900$ & $0.400$ & $0.300$ & $0.100$ & $0.600$ \\ 
   Management of companies and enterprises & $50$ & SP2MCE & $1$ & $0.500$ & $0.300$ & $0.200$ & $0.500$ \\ 
   Administrative and waste services & $50$ & SP2ADW & $2.600$ & $1.600$ & $1.100$ & $0.500$ & $1.100$ \\ 
   Administrative and support services & $50$ & 561000 & $2.400$ & $1.400$ & $1$ & $0.400$ & $1$ \\ 
   Waste management and remediation services & $50$ & 562000 & $5.100$ & $3.400$ & $2.200$ & $1.200$ & $1.700$ \\ 
   Educational and health services & $50$ & SP1EHS & $4.200$ & $2$ & $1.100$ & $0.800$ & $2.200$ \\ 
   Educational services & $50$ & SP2EDS & $2.100$ & $0.900$ & $0.600$ & $0.200$ & $1.200$ \\ 
   Educational services & $50$ & 611000 & $2.100$ & $0.900$ & $0.600$ & $0.200$ & $1.200$ \\ 
   Health care and social assistance & $50$ & SP2HSA & $4.500$ & $2.100$ & $1.200$ & $0.900$ & $2.400$ \\ 
   Ambulatory health care services & $50$ & 621000 & $2.400$ & $0.900$ & $0.600$ & $0.300$ & $1.500$ \\ 
   Hospitals & $50$ & 622000 & $6.200$ & $2.500$ & $1.500$ & $1$ & $3.700$ \\ 
   Nursing and residential care facilities & $50$ & 623000 & $7.100$ & $4.300$ & $2$ & $2.300$ & $2.800$ \\ 
   Social assistance & $50$ & 624000 & $3.500$ & $1.800$ & $1.300$ & $0.600$ & $1.600$ \\ 
   Leisure and hospitality & $50$ & SP1LEH & $3.600$ & $1.500$ & $1$ & $0.600$ & $2.100$ \\ 
   Arts entertainment and recreation & $50$ & SP2AER & $4.200$ & $2.100$ & $1.200$ & $0.900$ & $2.100$ \\ 
   Performing arts and spectator sports & $50$ & 711000 & $4.700$ & $2.200$ & $1.500$ & $0.700$ & $2.500$ \\ 
   Museums historical sites zoos and parks & $50$ & 712000 & $4$ & $2$ & $1.200$ & $0.800$ & $2$ \\ 
   Amusements gambling and recreation & $50$ & 713000 & $4.100$ & $2.100$ & $1.100$ & $0.900$ & $2$ \\ 
   Accommodation and food services & $50$ & SP2AFS & $3.500$ & $1.400$ & $0.900$ & $0.500$ & $2.100$ \\ 
   Accommodation & $50$ & 721000 & $4.900$ & $2.700$ & $1.400$ & $1.200$ & $2.300$ \\ 
   Food services and drinking places & $50$ & 722000 & $3.200$ & $1.200$ & $0.800$ & $0.300$ & $2$ \\ 
   Other services except public administration & $50$ & SP1OTS & $2.500$ & $1.200$ & $0.900$ & $0.400$ & $1.200$ \\ 
   Other services except public administration & $50$ & SP2OTS & $2.500$ & $1.200$ & $0.900$ & $0.400$ & $1.200$ \\ 
   Repair and maintenance & $50$ & 811000 & $3$ & $1.400$ & $1$ & $0.400$ & $1.600$ \\ 
   Personal and laundry services & $50$ & 812000 & $2.200$ & $1.400$ & $0.900$ & $0.500$ & $0.800$ \\ 
   Membership associations and organizations & $50$ & 813000 & $2$ & $0.900$ & $0.600$ & $0.200$ & $1.100$ \\ 
State and local government & $10$ & 000000 & $5$ & $2.300$ & $1.700$ & $0.600$ & $2.700$ \\ 
State government & $20$ & 000000 & $4.100$ & $2.100$ & $1.700$ & $0.400$ & $2$ \\ 
   Service providing & $20$ & SP1AAA & $4.100$ & $2.100$ & $1.700$ & $0.400$ & $2$ \\ 
   Educational and health services & $20$ & SP1EHS & $3.700$ & $1.900$ & $1.400$ & $0.500$ & $1.900$ \\ 
   Educational services & $20$ & SP2EDS & $2.100$ & $0.900$ & $0.600$ & $0.300$ & $1.300$ \\ 
   Educational services & $20$ & 611000 & $2.100$ & $0.900$ & $0.600$ & $0.300$ & $1.300$ \\ 
   Health care and social assistance & $20$ & SP2HSA & $8.100$ & $4.600$ & $3.600$ & $1$ & $3.500$ \\ 
   Hospitals & $20$ & 622000 & $8.700$ & $4.700$ & $3.600$ & $1.100$ & $4$ \\ 
   Nursing and residential care facilities & $20$ & 623000 & $12.600$ & $7.900$ & $6.200$ & $1.700$ & $4.600$ \\ 
   Public administration & $20$ & SP1PAD & $4.400$ & $2.300$ & $1.900$ & $0.400$ & $2.100$ \\ 
   Public administration & $20$ & SP2PAD & $4.400$ & $2.300$ & $1.900$ & $0.400$ & $2.100$ \\ 
   Justice public order and safety activities & $20$ & 922000 & $6.100$ & $3.300$ & $2.700$ & $0.500$ & $2.800$ \\ 
Local government & $30$ & 000000 & $5.400$ & $2.300$ & $1.700$ & $0.700$ & $3$ \\ 
   Goods producing & $30$ & GP1AAA & $8.600$ & $4.200$ & $3$ & $1.300$ & $4.300$ \\ 
   Construction & $30$ & GP1CON & $8.600$ & $4.200$ & $3$ & $1.300$ & $4.400$ \\ 
   Construction & $30$ & GP2CON & $8.600$ & $4.200$ & $3$ & $1.300$ & $4.400$ \\ 
   Heavy and civil engineering construction & $30$ & 237000 & $8.600$ & $4.200$ & $2.900$ & $1.300$ & $4.300$ \\ 
   Service providing & $30$ & SP1AAA & $5.300$ & $2.300$ & $1.700$ & $0.700$ & $3$ \\ 
   Trade transportation and utilities & $30$ & SP1TTU & $6.500$ & $3.600$ & $2.700$ & $0.800$ & $2.900$ \\ 
   Transportation and warehousing & $30$ & SP2TRW & $7.500$ & $4.500$ & $4$ & $0.500$ & $3$ \\ 
   Transit and ground passenger transportation & $30$ & 485000 & $7.100$ & $4.400$ & $4$ & $0.400$ & $2.700$ \\ 
   Utilities & $30$ & SP2UTL & $5.400$ & $2.700$ & $1.500$ & $1.200$ & $$ \\ 
   Utilities & $30$ & 221000 & $5.400$ & $2.700$ & $1.500$ & $1.200$ & $$ \\ 
   Educational and health services & $30$ & SP1EHS & $4.300$ & $1.600$ & $1.100$ & $0.500$ & $2.700$ \\ 
   Educational services & $30$ & SP2EDS & $4.100$ & $1.500$ & $1$ & $0.500$ & $2.600$ \\ 
   Educational services & $30$ & 611000 & $4.100$ & $1.500$ & $1$ & $0.500$ & $2.600$ \\ 
   Health care and social assistance & $30$ & SP2HSA & $5.600$ & $2.400$ & $1.600$ & $0.800$ & $3.200$ \\ 
   Hospitals & $30$ & 622000 & $5.700$ & $2.200$ & $1.400$ & $0.800$ & $3.600$ \\ 
   Nursing and residential care facilities & $30$ & 623000 & $7.400$ & $5.200$ & $3.500$ & $1.600$ & $2.300$ \\ 
   Public administration & $30$ & SP1PAD & $7.100$ & $3.400$ & $2.500$ & $0.900$ & $3.700$ \\ 
   Public administration & $30$ & SP2PAD & $7.100$ & $3.400$ & $2.500$ & $0.900$ & $3.700$ \\ 
   Justice public order and safety activities & $30$ & 922000 & $9.500$ & $4.800$ & $3.900$ & $0.900$ & $4.700$ \\ 
\hline \\[-1.8ex] 

\end{longtable}
\theendnotes
\end{document}

Answer 1

The etoolbox package provides a string equality test, which can be used like in the macro \cfootnote below. If you are happy to call the macro from the relevant cells, as in the first example below, then the footnotes will be added based on the cell value. Note the % at the end of the macro rows to prevent unwanted whitespace etc. during macro expansion.

If you want to automatically add footnotes without writing repeated macro calls then you can use the collcell package to define a new columntype that includes the macro call, as in the second example below. Note that there seems to be an incompatibility between longtable and collcell that results in errors, which can be fixed by adding a dummy column of a basic type to the table (and an extra & in every row, as well as & sequences in empty rows).

Furthermore I used the caption package and footnotemark, footnotetext to fix a footnote numbering issue.

MWE:

\documentclass{article}
\usepackage{longtable}
\usepackage{etoolbox}
\usepackage{collcell}
\usepackage{caption}

\newcommand*{\cfootnote}[1]{%
          #1%
          \ifstrequal{#1}{NAICS\_TITLE}{\footnote{Industry footnote}}{%
                \ifstrequal{#1}{TEI}{\footnote{NAICS footnote}}{%
                \ifstrequal{#1}{CDAFW}{\footnote{DAFW footnote}}{}%
            }%
        }%
}
\newcolumntype{L}{>{\collectcell\cfootnote}l<{\endcollectcell}}
%%%% First example
\begin{document}
\begin{longtable}{@{\extracolsep{-5pt}} llllllll}
\caption{First example. Incidence rates\protect\footnote{rates footnote} of nonfatal occupational injuries and illnesses by industry and case types, 2014}
\\[-1.8ex]\hline 
\hline \\[-1.8ex] 
\cfootnote{NAICS\_TITLE} & OWNERSHIP & \cfootnote{TEI} & TRC & \cfootnote{CDART} & CDAFW & CDJTR & CORC\\
\end{longtable}

%%%% Second example
\begin{longtable}{@{\extracolsep{-5pt}} LLLLLLLLr}
\caption{Second example. Incidence rates\protect\footnotemark\ of nonfatal occupational injuries and illnesses by industry and case types, 2014}\\[-1.8ex]
\footnotetext{rates footnote}&&&&&&&&\\[-1.8ex]\hline 
\hline &&&&&&&&\\[-1.8ex] 
NAICS\_TITLE & OWNERSHIP & TEI & TRC & CDART & CDAFW & CDJTR & CORC &\\
\end{longtable}
\end{document}

For future questions, please provide a complete code example (instead of just some lines from the table).

Sources used for this solution:

Comparing an argument to a string when argument is a result of a command with etoolbox

How to apply a macro to each column of a table

Is there an incompatibility between collcell, longtable, and/or arydshln?

how to have a caption on top of longtable?

---

EDIT: regarding automatic adding of extra &: this is probably easiest from R. For example:

library(xtable)
# data frame
df <- data.frame(A = c(1,2,3), B = c(4,5,6), DUMMY = character(3))
colnames(df)[3] <- ""
xtable(df)
# with some xtable options
print.xtable(xtable(df, display = c("s","d","d","s"), align="LLLr"),include.rownames=FALSE, floating=FALSE, tabular.environment='longtable')

# matrix
df2 <- matrix(c(c(1,2,3,4,5,6),character(3)),nrow=3,ncol=3,byrow=FALSE)
dimnames(df2) = list(character(3),c("A","B","DUMMY"))
colfunc <- function(col) { sub("DUMMY","",col) }
print.xtable(xtable(df2),sanitize.colnames.function=colfunc)

Note: xtable substitutes empty column names in a matrix, this can be solved by removing the column name using the sanitize option.

Regarding repeated footnotes: the fixfoot package comes close, it prints a single footnote for all occurrences on a given page. However, numbering is incremental. Alternatively, you can print all footnotes on the first page and use the corresponding \footnotemarks in the macro.