on the job

Question 1

check current working directory

Answer 1

import os
os.getcwd()

Question 2

change current working directory

Answer 2

import os
os.chdir(“<path>")</path>

Question 3

create path/filename connection

Answer 3

os.path.join(path, filename)

Question 4

reading excel

Answer 4

pd.read_excel(name, sheet_name = ‘Sheet’)

Question 5

reading excel and importint as all strings

Answer 5

pd.read_excel(filename, sheet_name = ‘Sheet’, dtype = str)

Question 6

count nr of rows in dataframe

Answer 6

len(df.index)

Question 7

subset a file to some variables

Answer 7

df_subset = df[[“col1”, “col2”]]

Question 8

rename all columns

Answer 8

df.columns = [‘col1’, ‘col2’]

Question 9

showing all rows with empty value in certain column

Answer 9

df[df[‘var’].isnull()]

Question 10

write to excel/csv

Answer 10

df.to_csv(‘filename.csv’, sep = ‘;’)
df.to_excel(‘filename.xlsx’)