Plotting multiple bar graphs in dynamic Python dataframe

Question

I have a dataframe 'grid' that looks like this:

COLUMN_NM    DISTINCT_COUNT    MAX_COL_VALUE    MIN_COL_VALUE   NULL_COUNT
COL_A         123                 456                111              56
COL_B         15678               222                4                 3456
COL_C         18994               456                76               43               
...

The data in COLUMN_NM is dynamic as this DataFrame gets loaded with different tables for analysis. What I want to do is graph the current data that resides in the DataFrame. I want a bar graph for DISTINCT_COUNT another for MAX_COL_VALUE etc...all per column. So the COLUMN_NM would be represented along the x-axis

What I have so far is incorrect clearly, but you get some idea of what I am trying to do.

distinct = grid[('COLUMN_NM', 'DISTINCT_COUNT')].plot(kind=bar)
max_col = grid[('COLUMN_NM', 'MAX_COL_VALUE')].plot(kind=bar)
min_col = grid[('COLUMN_NM', 'MIN_COL_VALUE')].plot(kind=bar)
null_cnt = grid[('COLUMN_NM', 'NULL_COUNT')].plot(kind=bar)

I have all the necessary import statements. I want the output to be 4 graphs, and I can specify more bar chart parameters after I get this working. Also, would it be easier to wrap this in a for loop, or function?

sacuL · Accepted Answer · 2018-06-08 16:12:40Z

2

Yes, I'd recommend doing this in a loop:

for col in ['DISTINCT_COUNT', 'MAX_COL_VALUE', 'MIN_COL_VALUE', 'NULL_COUNT']:
    grid[['COLUMN_NM', col]].set_index('COLUMN_NM').plot.bar(title=col)

The issues with your code were:

grid[('COLUMN_NM', 'DISTINCT_COUNT')] won't work because you are using a tuple, instead of [(...)] you want [[...]] to select a subset of columns
You also want to set the column by which you want your bars grouped (COLUMN_NM) as the index

answered Jun 8, 2018 at 16:12

sacuL

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1 Comment

JD2775 Over a year ago

thank you! I'll set this as answered but I just realized this puts the column names along the bottom, which would look messy if there are lots of them. I actually want them in a box in the upper right. That would look cleaner, then just a label at the bottom that reads 'Columns'. Any tips on that? If not I can mess around with it. Thanks again

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