Select first 4 rows of a data frame in R

Question

How can I select the first 4 rows of a data frame                 Weight Response 1   Control     59      0 0 2 Treatment     90      0 8 3 Treatment     47      0 1 4 Treamment    106      0 1 5   Control     85      0 7 6 Treatment     73      0 6 7   Control     61      0 2

User · Answer

For at DataFrame one can simply type  head data  num 10L    to get the first 10 for example   For a data frame one can simply type  head data  10    to get the first 10

User · Answer

Using the index   df 1 4     Where the values in the parentheses can be interpreted as either logical  numeric  or character  matching the respective names    df row index  column index    Read help      for more detail on this subject  and also read about index matrices in the Introduction to R

User · Answer

In case someone is interested in dplyr solution  it s very intuitive   dt  lt - dt   gt     slice 1 4

User · Answer

If you have less than 4 rows  you can use the head function   head data  4  or head data  n 4   and it works like a charm  But  assume we have the following dataset with 15 rows   gt data  lt - data  lt - read csv    data csv   sep        header TRUE    gt data  LungCap Age Height Smoke Gender Caesarean 1    6 475   6   62 1    no   male        no 2   10 125  18   74 7   yes female        no 3    9 550  16   69 7    no female       yes 4   11 125  14   71 0    no   male        no 5    4 800   5   56 9    no   male        no 6    6 225  11   58 7    no female        no 7    4 950   8   63 3    no   male       yes 8    7 325  11   70 4    no  male         no 9    8 875  15   70 5    no   male        no 10   6 800  11   59 2    no   male        no 11   6 900  12   59 3    no   male        no 12   6 100  13   59 4    no   male        no 13   6 110  14   59 5    no   male        no 14   6 120  15   59 6    no   male        no 15   6 130  16   59 7    no   male        no   Let s say  you want to select the first 10 rows  The easiest way to do it would be data 1 10       gt  data 1 10      LungCap Age Height Smoke Gender Caesarean 1    6 475   6   62 1    no   male        no 2   10 125  18   74 7   yes female        no 3    9 550  16   69 7    no female       yes 4   11 125  14   71 0    no   male        no 5    4 800   5   56 9    no   male        no 6    6 225  11   58 7    no female        no 7    4 950   8   63 3    no   male       yes 8    7 325  11   70 4    no  male         no 9    8 875  15   70 5    no   male        no 10   6 800  11   59 2    no   male        no   However  let s say you try to retrieve the first 19 rows and see the what happens - you will have missing values   gt  data 1 19        LungCap Age Height Smoke Gender Caesarean 1      6 475   6   62 1    no   male        no 2     10 125  18   74 7   yes female        no 3      9 550  16   69 7    no female       yes 4     11 125  14   71 0    no   male        no 5      4 800   5   56 9    no   male        no 6      6 225  11   58 7    no female        no 7      4 950   8   63 3    no   male       yes 8      7 325  11   70 4    no  male         no 9      8 875  15   70 5    no   male        no 10     6 800  11   59 2    no   male        no 11     6 900  12   59 3    no   male        no 12     6 100  13   59 4    no   male        no 13     6 110  14   59 5    no   male        no 14     6 120  15   59 6    no   male        no 15     6 130  16   59 7    no   male        no NA        NA  NA     NA   lt NA gt     lt NA gt        lt NA gt  NA 1      NA  NA     NA   lt NA gt     lt NA gt        lt NA gt  NA 2      NA  NA     NA   lt NA gt     lt NA gt        lt NA gt  NA 3      NA  NA     NA   lt NA gt     lt NA gt        lt NA gt    and with the head   function     gt  head data  19    or head data  n 19     LungCap Age Height Smoke Gender Caesarean 1    6 475   6   62 1    no   male        no 2   10 125  18   74 7   yes female        no 3    9 550  16   69 7    no female       yes 4   11 125  14   71 0    no   male        no 5    4 800   5   56 9    no   male        no 6    6 225  11   58 7    no female        no 7    4 950   8   63 3    no   male       yes 8    7 325  11   70 4    no  male         no 9    8 875  15   70 5    no   male        no 10   6 800  11   59 2    no   male        no 11   6 900  12   59 3    no   male        no 12   6 100  13   59 4    no   male        no 13   6 110  14   59 5    no   male        no 14   6 120  15   59 6    no   male        no 15   6 130  16   59 7    no   male        no   Hope this help

User · Answer

Use head   dnow  lt - data frame x rnorm 100   y runif 100   head dnow 4     default is 6

[r] Select first 4 rows of a data.frame in R

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