CODEWITHSUNDEEP
pythonexcelpandas
pHorseSpec
pHorseSpec

Reputation: 1274

Pandas Read Excel: how to access a given cell by column and row numbers

Using the Pandas module and the read_excel function, could I give each column I read in from an excel file a number assignment as a column header, so instead of using g_int_c=str(df1['Unnamed: 1'][6]) to refer to a piece of the data in the excel file, I could use g_int_c=str(df1[1][6])?

Example code is below:

import pandas as pd

with pd.ExcelFile(inputFile,
                      sheetname=['pnl1 Data ','pnl2 Data','pnl3 Data','pnl4 Data']) as xlsx:
        df1 = pd.read_excel(xlsx, 'pnl1 Data ',skiprows=9, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'])#assign column headers
        df2 = pd.read_excel(xlsx, 'pnl2 Data', skiprows=9, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'])
        df3 = pd.read_excel(xlsx, 'pnl3 Data', skiprows=9, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'])
        df4 = pd.read_excel(xlsx, 'pnl4 Data', skiprows=9, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'])

Upvotes: 1

Views: 21477

Answers (3)

pHorseSpec
pHorseSpec

Reputation: 1274

header=None,names=[0,1,2,3,4,5,6] worked. 

with pd.ExcelFile(inputFile,
                      sheetname=['pnl1 Data ','pnl2 Data','pnl3 Data','pnl4 Data']) as xlsx:
        df1 = pd.read_excel(xlsx, 'pnl1 Data ',skiprows=10, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'],header=None,names=[0,1,2,3,4,5,6])#assign column headers
        df2 = pd.read_excel(xlsx, 'pnl2 Data', skiprows=10, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'],header=None,names=[0,1,2,3,4,5,6])
        df3 = pd.read_excel(xlsx, 'pnl3 Data', skiprows=10, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'],header=None,names=[0,1,2,3,4,5,6])
        df4 = pd.read_excel(xlsx, 'pnl4 Data', skiprows=10, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'],header=None,names=[0,1,2,3,4,5,6])

Upvotes: 0

unutbu
unutbu

Reputation: 879511

To obtain nice column names instead of defaults like 'Unnamed: 1' use the names parameter of pd.read_excel. Mutatis mutandis, try replacing

with pd.ExcelFile(inputFile,
                  sheetname=['pnl1 Data ','pnl2 Data','pnl3 Data','pnl4 Data']) as xlsx:
    df1 = pd.read_excel(xlsx, 'pnl1 Data ',skiprows=9, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'])#assign column headers
    df2 = pd.read_excel(xlsx, 'pnl2 Data', skiprows=9, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'])
    df3 = pd.read_excel(xlsx, 'pnl3 Data', skiprows=9, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'])
    df4 = pd.read_excel(xlsx, 'pnl4 Data', skiprows=9, parse_cols="B:H", keep_default_na='FALSE', na_values=['NULL'])

with

sheets = ['pnl1 Data','pnl2 Data','pnl3 Data','pnl4 Data']
df = pd.read_excel(inputFile, sheetname=sheets, skiprows=9, parse_cols="B:H", 
                   names=list('BCDEFG'))
df = {i: df[sheet] for i, sheet in enumerate(sheets, 1)}

This will make df a dict, whose keys are sheet numbers and whose values are DataFrames. The DataFrames will have colum names B through G, roughly like the original Excel file.

Thus, instead of referring to numbered variables df1, ..., df4 (generally, a bad idea), you'll have all the DataFrames in the dict df and will be able to access them by numeric indexing: df[1], ..., df[4]. Sheet pnl3 Data, for example, would be accessed as df[3].

To access the seventh row, B column value of sheet 'pnl1 Data' of you could then use:

g_int_c = str(df[1].loc[6, 'B'])

For example,

import pandas as pd
try: from cStringIO import StringIO         # for Python2
except ImportError: from io import StringIO # for Python3
import textwrap
df1 = pd.read_csv(StringIO(textwrap.dedent("""
          ,,,
          0,1,2,3
          1,4,5,6
          7,8,9,10""")))
df2 = pd.read_csv(StringIO(textwrap.dedent("""
          ,,,
          0,NULL,2,3
          1,4,NULL,NULL""")), converters={i:str for i in range(4)})

sheets = ['pnl1 Data','pnl2 Data']

writer = pd.ExcelWriter('/tmp/output.xlsx')
for df, sheet in zip([df1, df2], sheets):
    print(df)
    #   Unnamed: 0 Unnamed: 1 Unnamed: 2 Unnamed: 3
    # 0          0       NULL          2          3
    # 1          1          4       NULL       NULL
    df.to_excel(writer, sheet)
writer.save()

df = pd.read_excel('/tmp/output.xlsx', sheetname=sheets, names=list('ABCD'), parse_cols="A:E")
df = {i: df[sheet] for i, sheet in enumerate(sheets, 1)}

for key, dfi in df.items():
    print(dfi)
    #    A  B  C   D
    # 0  0  1  2   3
    # 1  1  4  5   6
    # 2  7  8  9  10
    #    A    B    C    D
    # 0  0  NaN  2.0  3.0
    # 1  1  4.0  NaN  NaN

print(df[1].loc[1, 'B'])
# 4

Upvotes: 3

user6275647
user6275647

Reputation: 381

From the looks of your question, this isn't about assigning number values to columns upon import, but instead about how to access a given cell of a table by column and row numbers, which is a question specifically about how to index or slice a dataframe by integer.

In your example, you mentioned wanting to refer to df1[1][6]. You can do this by using .iloc.

# spin up a df
df = pd.DataFrame(np.random.randint(0,10,size=(7, 7)), columns=list('ABCDEFG'))
print df

Output:

   A  B  C  D  E  F  G
0  0  7  7  8  8  2  2
1  8  2  9  1  6  8  1
2  5  3  5  5  9  2  7
3  7  4  2  1  1  5  0
4  0  4  4  1  9  7  1
5  4  2  7  7  9  7  2
6  0  6  7  8  1  4  1

Now use .iloc to index by integer:

df.iloc[1,6]

Output:

1

To return to your code above, you could most likely change it to the following:

g_int_c=str(df.iloc[1,6])

For general references, here's the documentation on indexing and slicing dataframes: http://pandas.pydata.org/pandas-docs/stable/indexing.html#indexing-integer

And this Q&A might be helpful: How to get column by number in Pandas?

Upvotes: 2

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