dplyr::n() returns “Error: Error: n() should only be called in a data context ”

Question

I got for the following code

for (i in c(1:(ncol(df_multi_paths_cols) - 1))) {

  df_cache <- df_multi_paths_cols %>%
    select(num_range("ord_", c(i, i+1))) %>% 
    #select within dataset columns with prefix and within specific range i and i+1
    na.omit() %>% 
    # The na.omit R function removes all incomplete cases of a data object 
    # (typically of a data frame, matrix or vector).
    group_by(.dots = c(paste0("ord_", c(i, i+1)))) %>% 
    #paste=concatenate strings without separator
    #  group_by() takes an existing tbl and converts it into a grouped tbl where
    # operations are performed "by group". ungroup() removes grouping.
    summarise(number = n()) %>%
    # summarise() is typically used on grouped data created by group_by(). The output will 
    # have one row for each group.
    #n()=numbe robservation in the group
    ungroup()

    colnames(df_cache)[c(1, 2)] <- c('channel_from', 'channel_to')
    df_res[[i]] <- df_cache
}

The below error:

Error: n() should only be called in a data context

Searched on the web but seems no solution has been described related to this specific error. Any hints more than appreciated as I'm not able to figure out why the n() function is not working within summarise.

The dataframe df_multi_path_cols is like this:

> df_multi_paths_cols
     ord_1                        ord_2                    ord_3                     ord_4
1  (start)                MANAGER_SASWP            MANAGER_SRSLT             MANAGER_3RDWP
2  (start) GROUPDIRECTOR/CXO_LIVEWEBEXR GROUPDIRECTOR/CXO_SASWEB     GROUPDIRECTOR/CXO_WPR
3  (start)        GROUPDIRECTOR/CXO_SUG                   (null)                      <NA>
4  (start)        GROUPDIRECTOR/CXO_SUG  GROUPDIRECTOR/CXO_3RDWP GROUPDIRECTOR/CXO_SASLIVE
5  (start)        GROUPDIRECTOR/CXO_SUG    GROUPDIRECTOR/CXO_SUG                    (null)
6  (start)             DIRECTOR_3RDLIVE      DIRECTOR_ODSASWEBIN              DIRECTOR_SUG
7  (start)                DIRECTOR_DMCR             DIRECTOR_SUG                    (null)
8  (start)             DIRECTOR_3RDLIVE             DIRECTOR_SUG   GROUPDIRECTOR/CXO_SASWP
9  (start)                 DIRECTOR_SUG            DIRECTOR_EPCR             DIRECTOR_EPCR
10 (start)                 DIRECTOR_SUG             DIRECTOR_SUG             MANAGER_SASWP
11 (start)                  MANAGER_SUG                   (null)                      <NA>
                   ord_5                 ord_6                  ord_7                  ord_8
1          MANAGER_SASWP         MANAGER_EBOOK          MANAGER_3RDWP        MANAGER_ONASOFF
2           (conversion)                  <NA>                   <NA>                   <NA>
3                   <NA>                  <NA>                   <NA>                   <NA>
4  GROUPDIRECTOR/CXO_WBR GROUPDIRECTOR/CXO_SUG GROUPDIRECTOR/CXO_WDLR GROUPDIRECTOR/CXO_WDLR
5                   <NA>                  <NA>                   <NA>                   <NA>
6       DIRECTOR_ONASOFF          DIRECTOR_WPR            MANAGER_SUG           (conversion)

Update 04/07/2019

dput(df_multi_paths_cols)

structure(list(ord_1 = c("(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", 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"(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)", "(start)" ), ord_2 = c("MANAGER_SASWP", "GROUPDIRECTOR/CXO_LIVEWEBEXR", "GROUPDIRECTOR/CXO_SUG", "GROUPDIRECTOR/CXO_SUG", "GROUPDIRECTOR/CXO_SUG", "DIRECTOR_3RDLIVE", "DIRECTOR_DMCR", "DIRECTOR_3RDLIVE", "DIRECTOR_SUG", "DIRECTOR_SUG", "MANAGER_SUG", "TEAMMEMBER_3RDLIVE", "TEAMMEMBER_3RDLIVE", "TEAMMEMBER_OTHR", "TEAMMEMBER_SASLIVE", "DIRECTOR_3RDLIVE", "DIRECTOR_SASWP", "DIRECTOR_WBR", "TEAMMEMBER_EBOOK", "TEACHER_DMCR", "TEACHER_DMCR", "TEACHER_OTHR", "TEACHER_RMCHR", "TEACHER_SUG", "TEACHER_WBR", "DIRECTOR_DMCR", "DIRECTOR_DMCR", "DIRECTOR_DMCR", "DIRECTOR_SASEXEC", "DIRECTOR_SASLIVE", "DIRECTOR_SUG", "DIRECTOR_SUG", "DIRECTOR_SUG", "TEAMMEMBER_3RDWEBIN", "_SASLIVE", "DIRECTOR_SUG", "TEAMMEMBER_3RDLIVE", "DIRECTOR_SASEXEC", "DIRECTOR_SUG", "MANAGER_TEL", "DIRECTOR_SUG", "DIRECTOR_3RDLIVE", "DIRECTOR_DMCR", "DIRECTOR_SASLIVE", "DIRECTOR_SASLIVE", "DIRECTOR_SUG", "DIRECTOR_WBR", "MANAGER_3RDLIVE", "MANAGER_SASLIVE", "MANAGER_SUG", "_CR", "DIRECTOR_SASLIVE", "DIRECTOR_3RDLIVE", "DIRECTOR_3RDLIVE", "TEAMMEMBER_SASLIVE", "DIRECTOR_SUG", "DIRECTOR_TEL", "MANAGER_3RDLIVE", "MANAGER_IKR", "MANAGER_SASEXEC", "MANAGER_SASLIVE", "MANAGER_SEFR", "MANAGER_TEL", "_CR", "_AR", "_WPR", "DIRECTOR_SASLIVE", "TEAMMEMBER_DMR", "TEAMMEMBER_ID", "TEAMMEMBER_IKR", "TEAMMEMBER_SASEXEC", "TEAMMEMBER_SASLIVE", "TEAMMEMBER_SEFR", "TEAMMEMBER_SRSLT", "TEAMMEMBER_TEL", "MANAGER_EBOOK", "MANAGER_SEFR", "DIRECTOR_COMR", "DIRECTOR_CR", "DIRECTOR_DMR", "DIRECTOR_TEL", "TEAMMEMBER_TEL", "DIRECTOR_DMR", "DIRECTOR_SASLIVE", "DIRECTOR_SASLIVE", "DIRECTOR_SRSLT", "DIRECTOR_TEL", "DIRECTOR_TEL", "MANAGER_SASLIVE", "MANAGER_WPR", "MANAGER_WPR", "TEAMMEMBER_3RDLIVE", "TEAMMEMBER_Lead GenerationR", "TEAMMEMBER_SASLIVE", "TEAMMEMBER_COMR", "TEAMMEMBER_CR", "TEAMMEMBER_DMR", "TEAMMEMBER_IKR", "TEAMMEMBER_TEL", "DIRECTOR_IKR", "DIRECTOR_SASLIVE", "DIRECTOR_SASLIVE", "DIRECTOR_SASEXEC", "MANAGER_CS", "DIRECTOR_3RDLIVE", "DIRECTOR_RMCHR", "DIRECTOR_SASEXEC", "DIRECTOR_3RDLIVE", "DIRECTOR_SASWP", "MANAGER_CR", "DIRECTOR_IKR", "DIRECTOR_SASLIVE", "TEAMMEMBER_SASLIVE", "TEAMMEMBER_CR", "MANAGER_OTHR", "TEAMMEMBER_CR", "MANAGER_SRSLT", "DIRECTOR_DMR", "DIRECTOR_IKR", "MANAGER_COMR", "MANAGER_DMR", "MANAGER_IKR", "MANAGER_TEL", "DIRECTOR_SASLIVE", "MANAGER_3RDWP", "TEAMMEMBER_WS", "DIRECTOR_3RDLIVE", "DIRECTOR_SASLIVE", "_SASLIVE", "DIRECTOR_3RDLIVE", "TEAMMEMBER_3RDLIVE", "TEAMMEMBER_COMR", "TEAMMEMBER_WPR", "TEAMMEMBER_CR", "TEAMMEMBER_ARCHWEB", "TEAMMEMBER_ASKOD", "TEAMMEMBER_SASLIVE", "TEAMMEMBER_SASLIVE", "TEAMMEMBER_SASLIVE", "TEAMMEMBER_SASLIVE", "TEAMMEMBER_WS", "GROUPDIRECTOR/CXO_SASLIVE", "MANAGER_SASLIVE", "GROUPDIRECTOR/CXO_DMCR", "GROUPDIRECTOR/CXO_SASLIVE", "GROUPDIRECTOR/CXO_SEFR", "MANAGER_3RDLIVE",

Answer 1

The error disappeared by specifying for each function of the dplyr package the relative package of provenience:

for (i in c(1:(ncol(df_multi_paths_cols) - 1))) {

  df_cache <- df_multi_paths_cols %>%
    select(num_range("ord_", c(i, i+1)))   %>% 
    na.omit()  %>% 
    dplyr::group_by(.dots = c(paste0("ord_", c(i, i+1))))  %>% 
    dplyr::summarise(number=dplyr::n())  %>%
    ungroup() 

    colnames(df_cache)[c(1, 2)] <- c('channel_from', 'channel_to')
    df_res[[i]] <- df_cache
}

Pretty much now I think it was some kind of conflict with other packages with the same function name "summarise", as proved by

> conflicts()
  [1] "predictors"    "%>%"           "compact"       "lift"          "cols"          "%>%"          
  [7] "%>%"           "shift"         "take"          "transpose"     "%>%"           "add_row"      
 [13] "arrange"       "as_data_frame" "as_tibble"     "between"       "coalesce"      "count"        
 [19] "data_frame"    "data_frame_"   "desc"          "failwith"      "first"         "frame_data"   
 [25] "glimpse"       "id"            "last"          "lst"           "lst_"          "mutate"       
 [31] "n"             "rename"        "summarise"     "summarize"     "tbl_sum"       "tibble"       
 [37] "tribble"       "trunc_mat"     "type_sum"      "matches"       "%>%"           "%>%"          
 [43] "expand"        "expm"          "t"             "%>%"           "enexpr"        "enexprs"      
 [49] "enquo"         "enquos"        "ensym"         "ensyms"        "expr"          "quo"          
 [55] "quo_name"      "quos"          "sym"           "syms"          "vars"          "dcast"        
 [61] "melt"          "smiths"        "coerce"        "plot"          "print"         "show"         
 [67] "summary"       "t"             "cov"           "cov2cor"       "df"            "filter"       
 [73] "lag"           "lowess"        "predict"       "smooth"        "toeplitz"      "update"       
 [79] "var"           "image"         "plot"          "?"             "data"          "head"         
 [85] "tail"          "Arith"         "cbind2"        "coerce"        "Compare"       "kronecker"    
 [91] "Logic"         "Math"          "Math2"         "Ops"           "rbind2"        "show"         
 [97] "Summary"       "all.equal"     "as.array"      "as.matrix"     "body<-"        "chol"         
[103] "chol2inv"      "colMeans"      "colSums"       "crossprod"     "det"           "determinant"  
[109] "diag"          "diag<-"        "diff"          "drop"          "format"        "intersect"    
[115] "isSymmetric"   "kronecker"     "mean"          "norm"          "Position"      "print"        
[121] "qr"            "qr.coef"       "qr.fitted"     "qr.Q"          "qr.qty"        "qr.qy"        
[127] "qr.R"          "qr.resid"      "rcond"         "rowMeans"      "rownames"      "rowSums"      
[133] "setdiff"       "setequal"      "solve"         "summary"       "t"             "tcrossprod"   
[139] "union"         "unname"        "url"           "which"         "zapsmall"    

Answer 2

This is because of the conflicts in packages, i.e., summarize/summarise is present in both the "dplyr" package and the "plyr" package. It is likely the function got called from the wrong package, resulting in this error. We can call the function while referencing its package to avoid such an issue.

To demonstrate:

# Call summarise from plyr library
plyr::summarise(count = n())

# Call summarise from dplyr library
dplyr::summarise(count = n())

I think this will help, let me know if you have any issue. Cheers.