Import your data

data("mtcars")
mtcars <- as_tibble(mtcars)

# csv file
jobs_gender <- readr::read_csv("https://raw.githubusercontent.com/rfordatascience/tidytuesday/master/data/2019/2019-03-05/jobs_gender.csv")
## Rows: 2088 Columns: 12
## ── Column specification ────────────────────────────────────────────────────────
## Delimiter: ","
## chr (3): occupation, major_category, minor_category
## dbl (9): year, total_workers, workers_male, workers_female, percent_female, ...
## 
## ℹ Use `spec()` to retrieve the full column specification for this data.
## ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.

Repeat the same operation over different columns of a data frame

Case of numeric variables

mtcars %>% map_dbl(.x = ., .f = ~mean(x = .x))
##        mpg        cyl       disp         hp       drat         wt       qsec 
##  20.090625   6.187500 230.721875 146.687500   3.596563   3.217250  17.848750 
##         vs         am       gear       carb 
##   0.437500   0.406250   3.687500   2.812500
mtcars %>% map_dbl(.f = ~mean(x = .x))
##        mpg        cyl       disp         hp       drat         wt       qsec 
##  20.090625   6.187500 230.721875 146.687500   3.596563   3.217250  17.848750 
##         vs         am       gear       carb 
##   0.437500   0.406250   3.687500   2.812500
mtcars %>% map_dbl(mean)
##        mpg        cyl       disp         hp       drat         wt       qsec 
##  20.090625   6.187500 230.721875 146.687500   3.596563   3.217250  17.848750 
##         vs         am       gear       carb 
##   0.437500   0.406250   3.687500   2.812500
# Adding an argument
mtcars %>% map_dbl(.x = ., .f = ~mean(x = .x, trim = 0.1))
##         mpg         cyl        disp          hp        drat          wt 
##  19.6961538   6.2307692 222.5230769 141.1923077   3.5792308   3.1526923 
##        qsec          vs          am        gear        carb 
##  17.8276923   0.4230769   0.3846154   3.6153846   2.6538462
mtcars %>% map_dbl(mean, trim = 0.1)
##         mpg         cyl        disp          hp        drat          wt 
##  19.6961538   6.2307692 222.5230769 141.1923077   3.5792308   3.1526923 
##        qsec          vs          am        gear        carb 
##  17.8276923   0.4230769   0.3846154   3.6153846   2.6538462
mtcars %>% select(.data = ., mpg)
## # A tibble: 32 × 1
##      mpg
##    <dbl>
##  1  21  
##  2  21  
##  3  22.8
##  4  21.4
##  5  18.7
##  6  18.1
##  7  14.3
##  8  24.4
##  9  22.8
## 10  19.2
## # … with 22 more rows
mtcars %>% select(mpg)
## # A tibble: 32 × 1
##      mpg
##    <dbl>
##  1  21  
##  2  21  
##  3  22.8
##  4  21.4
##  5  18.7
##  6  18.1
##  7  14.3
##  8  24.4
##  9  22.8
## 10  19.2
## # … with 22 more rows

Create your own function

# Double values in columns
double_by_factor <- function(x, factor) {x * factor}
10 %>% double_by_factor(factor = 2)
## [1] 20
mtcars %>% map_dfr(.x = ., .f = ~double_by_factor(x = .x, factor = 10))
## # A tibble: 32 × 11
##      mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb
##    <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
##  1   210    60  1600  1100  39    26.2  165.     0    10    40    40
##  2   210    60  1600  1100  39    28.8  170.     0    10    40    40
##  3   228    40  1080   930  38.5  23.2  186.    10    10    40    10
##  4   214    60  2580  1100  30.8  32.2  194.    10     0    30    10
##  5   187    80  3600  1750  31.5  34.4  170.     0     0    30    20
##  6   181    60  2250  1050  27.6  34.6  202.    10     0    30    10
##  7   143    80  3600  2450  32.1  35.7  158.     0     0    30    40
##  8   244    40  1467   620  36.9  31.9  200     10     0    40    20
##  9   228    40  1408   950  39.2  31.5  229     10     0    40    20
## 10   192    60  1676  1230  39.2  34.4  183     10     0    40    40
## # … with 22 more rows
mtcars %>% map_dfr(double_by_factor, factor = 10)
## # A tibble: 32 × 11
##      mpg   cyl  disp    hp  drat    wt  qsec    vs    am  gear  carb
##    <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
##  1   210    60  1600  1100  39    26.2  165.     0    10    40    40
##  2   210    60  1600  1100  39    28.8  170.     0    10    40    40
##  3   228    40  1080   930  38.5  23.2  186.    10    10    40    10
##  4   214    60  2580  1100  30.8  32.2  194.    10     0    30    10
##  5   187    80  3600  1750  31.5  34.4  170.     0     0    30    20
##  6   181    60  2250  1050  27.6  34.6  202.    10     0    30    10
##  7   143    80  3600  2450  32.1  35.7  158.     0     0    30    40
##  8   244    40  1467   620  36.9  31.9  200     10     0    40    20
##  9   228    40  1408   950  39.2  31.5  229     10     0    40    20
## 10   192    60  1676  1230  39.2  34.4  183     10     0    40    40
## # … with 22 more rows

Repeat the same operation over different elements of a list

When you have a grouping variable (factor)

mtcars %>% lm(formula = mpg ~ wt, data = .)
## 
## Call:
## lm(formula = mpg ~ wt, data = .)
## 
## Coefficients:
## (Intercept)           wt  
##      37.285       -5.344
mtcars %>% distinct(cyl)
## # A tibble: 3 × 1
##     cyl
##   <dbl>
## 1     6
## 2     4
## 3     8
reg_coeff_tbl <- mtcars %>%
    
    # Split it into a list of data frames
    split(.$cyl) %>%
    
    # Repeat regression over each group
    map(~lm(formula = mpg ~ wt, data = .x)) %>%
    
    # Extract coefficients from regression results
    map(broom::tidy, conf.int = TRUE) %>%
    
    # Convert to tibble
    bind_rows(.id = "cyl") %>%
    
    # Filter for wt coefficients
    filter(term == "wt")
reg_coeff_tbl %>%
    
    mutate(estimate  =  -estimate,
           conf.low  =  -conf.low,
           conf.high =  -conf.high) %>%
    
    ggplot(aes(x = estimate, y = cyl)) +
    geom_point() +
    geom_errorbar(aes(xmin = conf.low, xmax = conf.high))

Create your own

Choose either one of the two cases above and apply it to your data

jobs_gender %>% map_dbl(.x = ., .f = ~mean(x = .x))
## Warning in mean.default(x = .x): argument is not numeric or logical: returning
## NA

## Warning in mean.default(x = .x): argument is not numeric or logical: returning
## NA

## Warning in mean.default(x = .x): argument is not numeric or logical: returning
## NA
##                  year            occupation        major_category 
##            2014.50000                    NA                    NA 
##        minor_category         total_workers          workers_male 
##                    NA          196054.86638          111515.35536 
##        workers_female        percent_female        total_earnings 
##           84539.51102              35.99971           49762.09339 
##   total_earnings_male total_earnings_female  wage_percent_of_male 
##                    NA                    NA                    NA
jobs_gender %>% map_dbl(.f = ~mean(x = .x))
## Warning in mean.default(x = .x): argument is not numeric or logical: returning
## NA

## Warning in mean.default(x = .x): argument is not numeric or logical: returning
## NA

## Warning in mean.default(x = .x): argument is not numeric or logical: returning
## NA
##                  year            occupation        major_category 
##            2014.50000                    NA                    NA 
##        minor_category         total_workers          workers_male 
##                    NA          196054.86638          111515.35536 
##        workers_female        percent_female        total_earnings 
##           84539.51102              35.99971           49762.09339 
##   total_earnings_male total_earnings_female  wage_percent_of_male 
##                    NA                    NA                    NA
jobs_gender %>% map_dbl(mean)
## Warning in mean.default(.x[[i]], ...): argument is not numeric or logical:
## returning NA
## Warning in mean.default(.x[[i]], ...): argument is not numeric or logical:
## returning NA

## Warning in mean.default(.x[[i]], ...): argument is not numeric or logical:
## returning NA
##                  year            occupation        major_category 
##            2014.50000                    NA                    NA 
##        minor_category         total_workers          workers_male 
##                    NA          196054.86638          111515.35536 
##        workers_female        percent_female        total_earnings 
##           84539.51102              35.99971           49762.09339 
##   total_earnings_male total_earnings_female  wage_percent_of_male 
##                    NA                    NA                    NA
# Adding an argument
jobs_gender %>% map_dbl(.x = ., .f = ~mean(x = .x, trim = 500))
## Warning in mean.default(x = .x, trim = 500): argument is not numeric or logical:
## returning NA
## Warning in mean.default(x = .x, trim = 500): argument is not numeric or logical:
## returning NA

## Warning in mean.default(x = .x, trim = 500): argument is not numeric or logical:
## returning NA
##                  year            occupation        major_category 
##                2014.5                    NA                    NA 
##        minor_category         total_workers          workers_male 
##                    NA               58997.0               32301.5 
##        workers_female        percent_female        total_earnings 
##               15238.5                  32.4               44437.0 
##   total_earnings_male total_earnings_female  wage_percent_of_male 
##                    NA                    NA                    NA
jobs_gender %>% map_dbl(mean, trim = 500)
## Warning in mean.default(.x[[i]], ...): argument is not numeric or logical:
## returning NA
## Warning in mean.default(.x[[i]], ...): argument is not numeric or logical:
## returning NA

## Warning in mean.default(.x[[i]], ...): argument is not numeric or logical:
## returning NA
##                  year            occupation        major_category 
##                2014.5                    NA                    NA 
##        minor_category         total_workers          workers_male 
##                    NA               58997.0               32301.5 
##        workers_female        percent_female        total_earnings 
##               15238.5                  32.4               44437.0 
##   total_earnings_male total_earnings_female  wage_percent_of_male 
##                    NA                    NA                    NA
jobs_gender %>% select(.data = ., total_earnings)
## # A tibble: 2,088 × 1
##    total_earnings
##             <dbl>
##  1         120254
##  2          73557
##  3          67155
##  4          61371
##  5          78455
##  6          74114
##  7          62187
##  8          99167
##  9          70456
## 10          71927
## # … with 2,078 more rows
jobs_gender %>% select(total_earnings)
## # A tibble: 2,088 × 1
##    total_earnings
##             <dbl>
##  1         120254
##  2          73557
##  3          67155
##  4          61371
##  5          78455
##  6          74114
##  7          62187
##  8          99167
##  9          70456
## 10          71927
## # … with 2,078 more rows
# Double Value in the Columns
double_by_factor <- function(x, factor) {x * factor}
10 %>% double_by_factor(factor = 2)
## [1] 20
jobs_gender %>% select(where(is.numeric)) %>% map_dfr(.x = ., .f = ~double_by_factor(x = .x, factor = 10))
## # A tibble: 2,088 × 9
##     year total_workers workers…¹ worke…² perce…³ total…⁴ total…⁵ total…⁶ wage_…⁷
##    <dbl>         <dbl>     <dbl>   <dbl>   <dbl>   <dbl>   <dbl>   <dbl>   <dbl>
##  1 20130      10242590   7824000 2418590     236 1202540 1261420  959210    760.
##  2 20130       9772840   6816270 2956570     303  735570  810410  607590    750.
##  3 20130        148150     83750   64400     435  671550  715300  653250    913.
##  4 20130        430150    177750  252400     587  613710  751900  558600    743.
##  5 20130       7545140   4400780 3144360     417  784550  919980  650400    707.
##  6 20130        441980    161410  280570     635  741140  900710  660520    733.
##  7 20130       1097030    728730  368300     336  621870  665790  550790    827.
##  8 20130       4890480   3543690 1346790     275  991670 1013180  909400    898.
##  9 20130       9906110   4608420 5297690     535  704560  902780  574060    636.
## 10 20130        146560     33870  112690     769  719270  975520  682070     NA 
## # … with 2,078 more rows, and abbreviated variable names ¹​workers_male,
## #   ²​workers_female, ³​percent_female, ⁴​total_earnings, ⁵​total_earnings_male,
## #   ⁶​total_earnings_female, ⁷​wage_percent_of_male
jobs_gender %>% select(where(is.numeric)) %>% map_dfr(double_by_factor, factor = 2)
## # A tibble: 2,088 × 9
##     year total_workers workers…¹ worke…² perce…³ total…⁴ total…⁵ total…⁶ wage_…⁷
##    <dbl>         <dbl>     <dbl>   <dbl>   <dbl>   <dbl>   <dbl>   <dbl>   <dbl>
##  1  4026       2048518   1564800  483718    47.2  240508  252284  191842    152.
##  2  4026       1954568   1363254  591314    60.6  147114  162082  121518    150.
##  3  4026         29630     16750   12880    87    134310  143060  130650    183.
##  4  4026         86030     35550   50480   117.   122742  150380  111720    149.
##  5  4026       1509028    880156  628872    83.4  156910  183996  130080    141.
##  6  4026         88396     32282   56114   127    148228  180142  132104    147.
##  7  4026        219406    145746   73660    67.2  124374  133158  110158    165.
##  8  4026        978096    708738  269358    55    198334  202636  181880    180.
##  9  4026       1981222    921684 1059538   107    140912  180556  114812    127.
## 10  4026         29312      6774   22538   154.   143854  195104  136414     NA 
## # … with 2,078 more rows, and abbreviated variable names ¹​workers_male,
## #   ²​workers_female, ³​percent_female, ⁴​total_earnings, ⁵​total_earnings_male,
## #   ⁶​total_earnings_female, ⁷​wage_percent_of_male