[column] add setcol-precision-more and -less #1609 #1650

- works on float, floatsi, currency, date columns

Thanks to @andycraig for contributing the original plugin!

visidata/features/change_precision.py

@@ -0,0 +1,46 @@
+__author__ = 'Andy Craig, andycraig (https://github.com/andycraig)'
+
+
+import re
+
+from visidata import vd, Sheet, Column, floatsi, currency, date
+
+date_fmtstrs = [
+    '%Y',
+    '%Y-%m',
+#    '%Y-W%U',
+    '%Y-%m-%d',
+    '%Y-%m-%d %H',
+    '%Y-%m-%d %H:%M',
+    '%Y-%m-%d %H:%M:%S',
+    '%Y-%m-%d %H:%M:%S.%f',
+]
+
+@Column.api
+def setcol_precision(col, amount:int):
+    if col.type is date:
+        try:
+            i = date_fmtstrs.index(col.fmtstr)
+        except ValueError:
+            i = 2
+        col.fmtstr = date_fmtstrs[(i+amount)%len(date_fmtstrs)]
+    elif col.type in (float, floatsi, currency):
+        if col.fmtstr == '':
+            col.fmtstr = f'%.{2 + amount}f'
+        else:
+            precision_str = re.match(r'%.([0-9]+)f', col.fmtstr)
+            if not precision_str is None:
+                col.fmtstr = f'%.{max(0, int(precision_str[1]) + amount)}f'
+    else:
+        col.type = float
+        if col.fmtstr == '':
+            col.fmtstr = '%.2f'
+
+
+vd.addMenuItems('''
+    Column > Set precision > more > setcol-precision-more
+    Column > Set precision > less > setcol-precision-less
+''')
+
+Sheet.addCommand('Alt+-', 'setcol-precision-less', 'cursorCol.setcol_precision(-1)', 'show less precision in current column')
+Sheet.addCommand('Alt++', 'setcol-precision-more', 'cursorCol.setcol_precision(1)', 'show more precision in current column')