Reading column names alone in a csv file

Question

I have a csv file with the following columns  id name age sex Followed by a lot of values for the above columns  I am trying to read the column names alone and put them inside a list  I am using Dictreader and this gives out the correct details  with open  details csv   as csvfile      i   quot name quot   quot age quot   quot sex quot       re csv DictReader csvfile      for row in re          for x in i              print row x   But what I want to do is  I need the list of columns    quot i quot  in the above case to be automatically parsed with the input csv than hardcoding them inside a list  with open  details csv   as csvfile          rows iter csv reader csvfile   next       header rows 1       re csv DictReader csvfile      for row in re          print row         for x in header                           print row x   This gives out an error Keyerrror  name   in the line print row x   Where am I going wrong  Is it possible to fetch the column names using Dictreader

User · Answer

The csv DictReader object exposes an attribute called fieldnames  and that is what you d use  Here s example code  followed by input and corresponding output   import csv file     path to file csv  with open file  mode  r   encoding  utf-8   as f      reader   csv DictReader f  delimiter          for row in reader          print  col         row col  for col in reader fieldnames     Input file contents   col0 col1 col2 col3 col4 col5 col6 col7 col8 col9 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99   Output of print statements     col0 00    col1 01    col2 02    col3 03    col4 04    col5 05    col6 06    col7 07    col8 08    col9 09     col0 10    col1 11    col2 12    col3 13    col4 14    col5 15    col6 16    col7 17    col8 18    col9 19     col0 20    col1 21    col2 22    col3 23    col4 24    col5 25    col6 26    col7 27    col8 28    col9 29     col0 30    col1 31    col2 32    col3 33    col4 34    col5 35    col6 36    col7 37    col8 38    col9 39     col0 40    col1 41    col2 42    col3 43    col4 44    col5 45    col6 46    col7 47    col8 48    col9 49     col0 50    col1 51    col2 52    col3 53    col4 54    col5 55    col6 56    col7 57    col8 58    col9 59     col0 60    col1 61    col2 62    col3 63    col4 64    col5 65    col6 66    col7 67    col8 68    col9 69     col0 70    col1 71    col2 72    col3 73    col4 74    col5 75    col6 76    col7 77    col8 78    col9 79     col0 80    col1 81    col2 82    col3 83    col4 84    col5 85    col6 86    col7 87    col8 88    col9 89     col0 90    col1 91    col2 92    col3 93    col4 94    col5 95    col6 96    col7 97    col8 98    col9 99

User · Answer

You can read the header by using the next   function which return the next row of the reader   s iterable object as a list  then you can add the content of the file to a list  import csv with open  quot C  path to  filecsv quot    quot rb quot   as f      reader   csv reader f      i   reader next       rest   list reader   Now i has the column s names as a list  print i  gt  gt  gt   id    name    age    sex    Also note that reader next   does not work in python 3  Instead use the the inbuilt next   to get the first line of the csv immediately after reading like so  import csv with open  quot C  path to  filecsv quot    quot rb quot   as f      reader   csv reader f      i   next reader       print i       gt  gt  gt   id    name    age    sex

User · Answer

I literally just wanted the first row of my data which are the headers I need and didn t want to iterate over all my data to get them  so I just did this  with open data   r   newline     as csvfile  t   0 for i in csv reader csvfile  delimiter      quotechar           if t  gt  0          break     else          dbh   i         t    1

User · Answer

Though you already have an accepted answer  I figured I d add this for anyone else interested in a different solution-   Python s DictReader object in the CSV module  as of Python 2 6 and above  has a public attribute called fieldnames  https   docs python org 3 4 library csv html csv csvreader fieldnames   An implementation could be as follows   import csv  with open  C  mypath to csvfile csv    r   as f      d reader   csv DictReader f        get fieldnames from DictReader object and store in list     headers   d reader fieldnames      for line in d reader           print value in MyCol1 for each row         print line  MyCol1      In the above  d reader fieldnames returns a list of your headers  assuming the headers are in the top row   Which allows      gt  gt  gt  print headers    MyCol1    MyCol2    MyCol3     If your headers are in  say the 2nd row  with the very top row being row 1   you could do as follows   import csv  with open  C  mypath to csvfile csv    r   as f       you can eat the first line before creating DictReader       if no  fieldnames  param is passed into      DictReader object upon creation  DictReader      will read the upper-most line as the headers     f readline        d reader   csv DictReader f      headers   d reader fieldnames      for line in d reader           print value in MyCol1 for each row         print line  MyCol1

User · Answer

here is the code to print only the headers or columns of the csv file   import csv HEADERS   next csv reader open  filepath csv     print  HEADERS    Another method with pandas  import pandas as pd HEADERS   list pd read csv  filepath csv   head 0   print  HEADERS

User · Answer

Thanking Daniel Jimenez for his perfect solution to fetch column names alone from my csv  I extend his solution to use DictReader so we can iterate over the rows using column names as indexes  Thanks Jimenez    with open  myfile csv   as csvfile       rest          with open  myfile csv    rb   as f          reader   csv reader f          i   reader next           i i 1           re csv DictReader csvfile          for row in re              for x in i                  print row x

User · Answer

import pandas as pd data   pd read csv  quot data csv quot   cols   data columns

User · Answer

How about with open csv input path   file   r   as ft      header   ft readline     read only first line  returns string     header list   header split        returns list  I am assuming your input file is CSV format  If using pandas  it takes more time if the file is big size because it loads the entire data as the dataset

User · Answer

I am just mentioning how to get all the column names from a csv file  I am using pandas library   First we read the file   import pandas as pd file   pd read csv  details csv     Then  in order to just get all the column names as a list from input file use -  columns   list file head 0

[python] Reading column names alone in a csv file

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